Ram Air Myth

[MistrThou]

OK. Here's something that you ram air folk wont be too proud of...

http://www.vetteguru.com/ramair/

[stylngle2003]

yea, its mostly a myth, but if youre "ramming" air in, its likely a more straight flow path, which might gain you some hp

[MistrThou]

Wonderful Statics and Dynamics.

[Mblesso]

why is it that I had to turn down the boost when i built a ram air system in my car?
I am not doubting this, but simply asking.

[stylngle2003]

what that article basically said was ram air doesnt work at automotive velocities...ie, it does not "ram" air in any faster. you prolly had to lower boost because you still made a better performing intake which fed your engine more air

[Hank Scorpio]

raming air into a turbo :roll:

[stylngle2003]

no matter what, its not coming into the snail at more than 14.7 psi (elevation dependent, of course), so its not generating pressure or anything, just drawing more air into the engine by providing a more direct path to the intake.

[DerSnart]

Ram Air's only benefit is the fact (a roughly insignificant one at that) you are getting slightly cooler air.

I have Ram Air, its called a turbo... works great!

[procainestart]

http://corner-carvers.com/forums/showthread.php?t=15487&highlight=ram+air

Read all the way to the last post at the bottom...

[DerSnart]

By the time it goes through the MAF (or whatever it is your car uses to measure incoming air), past the TB and works its way into the head through all the runners and past the valves the actual effect might be decreased a bit. So I would argue that his math might be slightly "off". Ram Air can be effective, but for any normal street driven car I would argue it almost pointless. Its really one of those "lookie at what I gots guyz" kind of mods imo. On a Top Fuel dragster, or a F1 car I could see it being beneficial, they go high speeds on a regular basis... but for the rest of us stuck in 5pm traffic at 40mph... or for those of us going to 7-11 to get beer at 2am... I dont thinks its worth the effort. That just my opinion...

Also, is .32psi (assuming it doesn't encounter any resistance on its way to the engine) really worth it? I say get a "normal" intake and spend whats left over on a tune up or a Zagnut should they be available in your area.

[DerSnart]

why is it that I had to turn down the boost when i built a ram air system in my car?
I am not doubting this, but simply asking.

Your air supply (not the band) was increased would be my guess... how much did you have to turn it down?

PS: Your sig is repulsive! wtf is that?

[tjts1]

This was long on theory and short on facts. One interesting article deserves another.
"Eliminating negative boost"
http://www.autospeed.com/cms/A_0629/article.html?popularArticle

Read this all 5 parts then we can discuss the merrits of ram air. In short, yes ram air does work, no not the extent that you would want to advertise it on the hood. But it has its place beyond a regular cold air intake especially if you are looking for throttle response at freeway speeds.

[Bishop]

Ram Air a myth?, I strongly disagree, although I really am not good enough with maths or words to argue that particular guys ramblings.
I just know that power can be increased via air velocity into any intake, by turning any air box from a negative pressure environment, to a positive pressure environment, thus reducing any engines need to "suck" through anything, kind of like overcoming intake restriction by another means.

I think if the guy really thinks it's a myth, he should ask Kawasaki why they had a major advantage with the early ZZR1100's until everyone else caught on, then caught up.
The first ram air Kawasakis made more power moving, than on a dyno, and also caused some major engine tuners headaches when it came time to find more power with jetting kits and pipes.

I don't think it's as confusing clear cut as that guy claims it is, as it was, the article was insanely boring to read, like the ramblings of a mad science teacher who thinks he knows it all.

I would never say for sure I'm 100% right about it all, but it would take a lot more than one mans pitch to convince me something does not exist.

[volvogeek]

Your air supply (not the band) was increased would be my guess... how much did you have to turn it down?

PS: Your sig is repulsive! wtf is that?That's a ghost spewing ectoplasm all over a frat boy. Didn't you ever watch Ghostbusters?

[Bishop]

This was long on theory and short on facts. One interesting article deserves another.
"Eliminating negative boost"
http://www.autospeed.com/cms/A_0629/article.html?popularArticle

Read this all 5 parts then we can discuss the merrits of ram air. In short, yes it works, no not the extent that you would want to advertise it on the hood. But it has it place especially if you are looking for throttle response at freeway speeds.

I was going to quote that article as well, but thought it was still subscriber only content... :lol:

[DerSnart]

The classic "Home Depot" intake... dryer hose is hawt! As for the merits, I agree with you. It has an effect, but its so small I wouldn't call it the answer to all of the automotive industry's/enthusiasts performance needs.

Ram Air does have a purpose for automobiles after all...


http://www.draglist.com/photoimages/POD-0203/Dodge%20Ram%20Jet%20Pickup%20with%20the%20J-85%20option.%20Photo%20by%20James%20Morgan.jpg

[ashvolvo]

Is a turbocharger not an engine driven air-pump? thus acheiving a variant of 'ram air'
The effect of a ram-air setup depends on many variables, to write an article backed up by so few actual facts and some very broad basic calculations shows that an article such as this shouldnt be taken seriously.

Just because something is written on the internet does not make it correct.

[davidmacq]

A little education is a dangerous thing. As soon as one begins to think he has learned something he is in danger of beging more stupid. Mathmatics and such is only a simple model of reality, whenever your calculations don't coincide with reality you can be sure you are wrong.

As someone above said, ram air is just good to remove inefficiencies from a poor intake. Improve throttle response, etc. Improve effieciency of an installed turbo slightly, give it an extra .5 psi more air to start with.

The other article is good about explaining negative pressures in intakes, n such.

What I don't understand is he says fluid dynamics. Well fluid isn't compressible, and gas is. I guess his conclusion that air isn't compressible at slow speeds leads him to apply fluid dynamics to the situation.

So I guess he is saying just for arguement if you put a megaphone on top of your car. (big cheerleading cone) Big end facing front of car. He is saying that the air will refuse to be pushed through the small end of the cone and will just go around the cone.

Bleah

[11110000]

Working with jet engines, I see how this theory is really applied. A ram-air jet engine (RAMJET or SCRAMJET) does not work until you achieve several hundred mph. No, this is not the exact same thing as measing a ram-air effect on a car, but the idea is that generating a natural 'boost' effect is not valid. Especially when you consider the rate at which your engine is consuming that incoming air at highway speeds.

I absolutely understand the improved throttle response - With the throttle plate closed at high speed, you end up with a little pocket of air built up and ready to go - almost like a charged-up capacitor in an audio system. When you crack the throttle again, you get instant response.

So my take is - ram air as a concept is not a power-adder, but it does help response, and maybe adds a bit of power where the stock intake really sucks.

[vinnie_da_pooh]

Most car folks know that Ram Air is a marketing tool, has been since the sixties, and is very effective for its target audience. We should not completely discount the psycological impact or the "Seat of the Pants" effect to employ the technical term.

For example the hat belonging to the proud owner of a 1985 Berlinetta Camaro, who has his air cleaner top flipped upsidedown, will most likely be turned with the brim to the rear. This signifies his firm grasp of fluid dynamics, his cocksure outlook on life and the ultimate knowledge that his car is wicked, WICKED, fast.

The hat belonging to the owner of a crazy ill WS6, Stage IV, Ram Air Pontiac Firebird, will be tilted askew several degrees to port - indicating again a sure, confidant attitude and a deep assurance that his ram air phallus is cradling him in a well marketed image that could best be discribed as uh ...crazy, ill, dope, fresh, hype? Look at the smug smile, the loudly revving engine at every stoplight, the triple extra large team jersey worn to hide their needle dick. I ask you are these two men not well served by their ram air? Look at the hats all you armchair engineers, is this not a quantification of the benifit of ram air?

For a final example we look at the hat belonging to the proud owner of an ice cream truck white 1986 Volvo 245dl equiped with factory floormats but alas no ram air. His hat is wool navy surplus, his eyes are sad, his lips are blue. His hat signifies that he is cold because his blower moter will not Ram Air so he has resorted to Ram Vodka because he is poor and cold and his nuts drag uncomfortably on the gound when he walks.

Crosby, Stills, Nash and Young sang: "Find the price of freedom buried in Ram Air."

[mfpmax]

The SR71 Blackbird uses a "Ram Air Effect" to create a supercharger like effect at the tip of the engine, it has a adjustable cone tip that moves to vary the speed of air entering the engine.

[the poi]

So I guess he is saying just for arguement if you put a megaphone on top of your car. (big cheerleading cone) Big end facing front of car. He is saying that the air will refuse to be pushed through the small end of the cone and will just go around the cone.
Yes, this is the point; hence the statement that air is noncompressible at lower speeds. In our case, under 150 or so when it becomes marginally compressible. Im gonna try to figure a way to do this this weekend, I got two big fans and a case fan with an RPM sensor in it and enough paper for some right proper ducting....

[mikep]

"The answer is “divergent”. Yes, the nozzle would have to shaped so that the skinny end is pointed into the air stream, and the fat end connects to the throttle plate. How can this be right? Remember, to increase the static pressure of the intake air (which is the true “ram air” effect), the kinetic energy of the air must be traded to compress the air. This is done by slowing the air down, or stagnating it, and the only way to do this is with a diverging nozzle. Ah, but since air is incompressible at automobile speeds, it doesn’t matter any way. "



Wrong. It always has been and always will be.
This is what happens when you learn just enough to overthink a situation.
He is confusing the Bernoulli effect with air flow/pressure pertaining to drag and force.
The slowing of the air, and hence the rise in pressure, is because of a fixed intake need per cylinder.
The greater the area of an air opening (or a flat surface perpendicular to the air flow, for that matter) and the higher the speed, the greater the pressure. I didn't have the formulas here, but a similar idea is at:
http://www.thefoolonthehill.co.uk/kitelift.html
If a given orifice (or engine) can flow below less than the volume being fed, the pressure rises. Maybe not much, but it rises.


P.S.
"below mach .5 air is considered incompressible"
hahahahahaha.

[Matt Dupuis]

All That Stuff
Goddam, that's funny **** right there!

(shifts his oversize nuts 'cause he don't wear hats)

[n xntrx volvo]

that article only works if the engine has a 100% ve. the further you are the more you'll notice the effect. ram air is good on cars such as 240's that are very sensitive to headwinds. i noticed no major effect below 75mph, unless passing a cab over, or other more brick like large trucks.

[SquareD]

I agree with Matt, vinnie_da_pooh has the post of the week right there!

For example the hat belonging to the proud owner of a 1985 Berlinetta Camaro, who has his air cleaner top flipped upsidedown, will most likely be turned with the brim to the rear. This signifies his firm grasp of fluid dynamics, his cocksure outlook on life and the ultimate knowledge that his car is wicked, WICKED, fast.

LMAO, good stuff!

[740Weapon]

mikep surely took fluid mechanics. i was going to say what he said.

ram air is a joke. cold air is however NOT a joke.

[mikep]

mikep surely took fluid mechanics.

The only college science I have ever taken was chem. But I read anything I can find. And I remember everything I ever read/see.

[Dan242tic]

The only college science I have ever taken was chem. But I read anything I can find. And I remember everything I ever read/see.

I can see that being a liability, some things should be forgotten. As far as Ram-Air, its good for showing off to the guys who think led washer nozzles are a go-fast mod. It might make a small difference at 75 mph and up, but its main advantage is bringing in outside air to the intake as stated above.

[mikep]

It might make a small difference at 75 mph and up, but its main advantage is bringing in outside air to the intake as stated above.
I agree.
That and it makes sure you don't have any heinous restrictions in the inlet.

[BDKR]

I suspect that IF the whole RAM idea was totally pointless, the big Japanese and Italian motorcycle makers wouldn't keep adding them to their bikes. The point is that they do. And not just in their street bikes, but the racers as well.

A few examples.
http://www.volny.cz/vaseksedo3/page_2/ZX-7.JPG

http://moto.power.free.fr/graphisme/wallpaper/1024-768/wallpaper%20kawasaki%20ZX%2012%20R%20azul%20.jpg

http://www.racingaprilia.com/dati/304/foto_mag_head_1103_1099244075.jpg

http://sportrider.com/bikes/146-0110-SHOW-01-zoom.jpg

Using ram air in high performance engines goes back to WWII. And FYI, Kawasaki produced a fighter in that war.

Now sure, a lot of those companies making the "Ram air" intake systems for cars are just manipulating the ignorance of the average ricer to make a dollar. And it's a crying shame, but let's not react to that and ignore the fact that it's use must mean something to these large ventures or else they wouldn't continue to use it.

I'm not going to go into a huge diatribe on this (I want to sit on my ass and watch a little TV), but look at the characteristics of what the motorcycle guys are calling ram air systems (and not just that hole in the front of the fairing, but the entire system all the way to the throttle bodies) then compare it to what's being sold or even created as mods buy a lot of car guys. It's not the same thing.

Cheers,
BDKR

[Unregistered]

Hello all

Seen "turbo" and had to poke around... Looking for Pontiac 301T info and here I am.

I have to comment first on the misinformation regarding the Trans Am.. Ram Air III and RA IV (and HO)had nothing to do with ram air they were simply some bad ass cylinder heads with round exhaust ports instead of the normal "D" ports... Availible '69 through '72 ('73?) These motors made gobs of power... Ram Air was an option on these early formulas and the T/A shaker was open during the same years...

WS6 was originally ('79-81) a suspension package (including 4-wheel disc brakes) inspired by Herb Adams '78 Fire AM designed by Lotus.

At second glance you may be speaking of the mid-'90s T/A and well all I can say to that they cost way to much, But you gotta admit those newer RA T/A's look mean as hell...

You guys have overlooked one big problem with ram air, rain. That's why us T/A guys open our shacker scoops to add cowl induction. Bottom line with ram air. In motion you will have no shortage of "cold" air and probably a straighter/shorter line to the intake than drawing it through the fire wall which will increase performance.

It's all 'bout looks and bragging rights, What's the difference between souping up a Volvo or a Camaro. The goal is same, Better performance than stock (factory HP on the F-bodys was pethetic all through the '70 and most of the 80's)

The only difference I can see in street rod terms are that Volvo's are sleepers.

Go easy on the stereotypes... Cause the handful I can think of (regarding Volvo drivers) probably doesn't fit most you guys... Nuckle dragging cave men pull up in all kinds of rides. ( I will admit they do seem drawn to 'maro a real Poncho motor is way over their heads though)

Any moron can run down to the speed shop spend to much money only to end up with a mismatched poorly tooned POS that HE is certian will blow the doors off of anything.

I'll rumble off with my Poncho now...

FuzzyRick

[dl242gt]

My little bit of change to offer is the aforementioned cowl induction and
a Porsche 911 with the older duck tail spoiler. Every car has areas on it where
the air has higher pressure from traveling through it. Manufacturers take
advantage of this for helping the air intake to the motor and it makes
for great marketing. The base of the windshield and the base of the ducktail
provide the same effect. A high pressure area that provides a bit more
airflow into the motor than what might normally be available.

Mmmm, air.

[mikep]

I have to comment first on the misinformation regarding the Trans Am.. Ram Air III and RA IV (and HO)had nothing to do with ram air they were simply some bad ass cylinder heads
Nice to meet you, Rick.
Doug and I knew that, except the "ram air" was actually referring to the tuning effect of a runner, but then the marketing guys ran away with it.
I used to specialize in 389, 400 and 455 builds. Doug is just a sick and demented guy who had some evil Pontiacs and an even more evil Volvo.

And as far as stereotypes, this is Off Topic, and most of it is said(typed) in a joking manner.

[745 TurboGreasel]

Seems there may be yet another factor...not whith NA cars, but IAT on a turbo is proportional to the amount of pressure increase by the turbo, therefore any Increase in inlet side pressure, even half a pound is that much less heat introduced into the system, and will be added to the small gain from the positive pressure inlet location.

every littlte bit helps, and its free energy, there is always going to be a point on the car that has the higest pressure at criuse, why not harness it?

[PRVersion]

The SR71 Blackbird uses a "Ram Air Effect" to create a supercharger like effect at the tip of the engine, it has a adjustable cone tip that moves to vary the speed of air entering the engine.

i'm sure this is useful, expecially around mach 4.5 or so :-P

[Hagar17]

When designing intake pathways...this may be relevent...

http://www.cvphysiology.com/Hemodynamics/H007.htm

[mikep]

http://www.nasa.gov/missions/research/x43-main.html

big boys version
http://en.wikipedia.org/wiki/Scramjet

for the 'tards
http://www.aviation-history.com/engines/ramjet.htm

[barefoot]

even half a pound is that much less heat introduced into the system

If you were able to harness all the stagnation pressure developed at the front of the moving car as "ram pressure" in the intake, with no losses at all, you're not going to make half a pound until the car is doing 275 km/h. That's about 170 mph.

Ram air is real. It's measurable. It's harnessable. It's quite irrelevant at road speed.

0.05psi at 55mph. I can fart harder than that.

tim

[BB-Q]

Suzuki claimed to have used Fluid Dynamics to design the fairing on the Suzuki Hayabusa mentioned above- including the air intakes. It has always gone faster than the static dyno tests say it should

[Captain Bondo]

If you were able to harness all the stagnation pressure developed at the front of the moving car as "ram pressure" in the intake, with no losses at all, you're not going to make half a pound until the car is doing 275 km/h. That's about 170 mph.

Ram air is real. It's measurable. It's harnessable. It's quite irrelevant at road speed.

0.05psi at 55mph. I can fart harder than that.

tim

Exactly. And you'll be lucky if you can just barely manage to compensate for the additional pressure drop the extra plumbing is generating. We've both beaten our drumsticks to splinters on this gong many many times. :rofl:

[barefoot]

Suzuki claimed to have used Fluid Dynamics to design the fairing on the Suzuki Hayabusa mentioned above- including the air intakes. It has always gone faster than the static dyno tests say it should

Uh...I claim to have used Fluid Dynamics to calculate the pressures above. Bernoiulli's principle. Second year engineering stuff.

Sure, fluid dynamics is rocket science, but it sure ain't brain surgery :-P :???: :rofl:

If you designed a fairing without using fluid dynamics, you'd be...well...you'd be a stylist, not an engineer.

And like I said above, theoretical limit of ram air pressure at 275km/h is 0.5psi. A quick bike will do that kind of speed. Half a pound is an appreciable boost when you're trying to stretch the limit.

It's real, measurable, harnessable, and irrelevant at road speeds.

tim

[BB-Q]

Uh...I claim to have used Fluid Dynamics to calculate the pressures above. Bernoiulli's principle. Second year engineering stuff.

Sure, fluid dynamics is rocket science, but it sure ain't brain surgery :-P :???: :rofl:

If you designed a fairing without using fluid dynamics, you'd be...well...you'd be a stylist, not an engineer.

And like I said above, theoretical limit of ram air pressure at 275km/h is 0.5psi. A quick bike will do that kind of speed. Half a pound is an appreciable boost when you're trying to stretch the limit.

It's real, measurable, harnessable, and irrelevant at road speeds.

tim

Fair enough. It was merely an observation that, as you so rightly pointed out, has a basis in fact.
To be honest, I was probably pointing out more that people forget how advanced motorcycle technology is.

[PRVersion]

last years new suzuki gs-r or whatever with its 18,000rpm redline...

hard to forget the gap in technology :-P

[linuxman51]

but for the rest of us stuck in 5pm traffic at 40mph... or for those of us going to 7-11 to get beer at 2am... I dont thinks its worth the effort. That just my opinion...



you clearly have not gone on a beer run with me, the other day I did a roll on against a low flying f-16, he didnt stand a chance.

[BrickBaller]

Seems to me that since ram-air intakes produce a real, though negligible, increase, it would be more important to design a . . . (drumroll)

Laminar Flow Intake

Now that sounds sexy. Basic idea behind it would be to increase the diameter of the intake pipes. This has two effects, both realized from the reduction in flow velocity. A lower flow velocity will reduce frictional effects from the boundary layer on the walls of the tube, and secondly it will reduce the Reynold's number and, hopefully, resulting in laminar flow.

Of course if you can figure out how to have laminar flow at high velocities the Air Force will abduct you and force you to make an F-14 go to mach 15.

Besides, if it looks good does it matter if it works? I doubt that the increase in drag will slow you down much. . .

[Vee_Que]

A CAI definetly improves the air quality going into the engine, in theory, that's why with a lot of CAI's the engine does have a bit more poke.

[brucepick]

...So I guess he is saying just for arguement if you put a megaphone on top of your car. (big cheerleading cone) Big end facing front of car. He is saying that the air will refuse to be pushed through the small end of the cone and will just go around the cone. Bleah

I did see an excellent piece by a guy who decided the same thing after some good real-world testing:
http://www.karlsnet.com/mopar/ramair.shtml

He did quite a few real-world tests. He rigged up rigid tubes with a pressure sensor; if I recall he mounted them on his car somewhere. Took mesurements on wide-mouth funnel-type intakes and found that the outlet end was what determined the amount of pressure and of air flow. Size of "mouth" at the front end had absolutely no effect. The big mouth did nothing, as usual... (couldn't resist that one)

He also tested for pressure (or flow??) using straight ducts parallel to the direction of travel, and with various degrees of tilt and/or bend in the duct. Also tested corrugated duct vs. smooth duct. If you're thinking about ram air or cold air intake, you've got to read this guy.

[JohnMc]

The SR71 Blackbird uses a "Ram Air Effect" to create a supercharger like effect at the tip of the engine, it has a adjustable cone tip that moves to vary the speed of air entering the engine.
Actually, the purpose of that cone was to restrict air flow into the motor. At massively supersonic speeds they need to restrict the volume and reduce the speed of the air, or it will simply blow out the combustion. Flame can't travel upwind past a certain speed, I guess.

So those are sort of like the opposite of ram air.

[BDKR]

Actually, the purpose of that cone was to restrict air flow into the motor. At massively supersonic speeds they need to restrict the volume and reduce the speed of the air, or it will simply blow out the combustion. Flame can't travel upwind past a certain speed, I guess.


Bingo! Suprised the injurkneers above didn't pick that up. :roll:

[Hagar17]

Ok boffins lets take some of these 'ram air' theories to the track and show us some timings.

I declare shenannigans on the lot!

[BDKR]

...was probably pointing out more that people forget how advanced motorcycle technology is.


At least they realize something that all of us with turbos and boost gauges with numbers should be able to see and realize ourselves. All you have to do is look at your boost guage and note how the car runs in the region of zero boost / zero vacuum and just a little beyond. I put emphasis on the last part of that sentence becuase that's all the (Motorcycle) factory Ram Air systems are ever producing. A very slight over pressure effect (in comparison to what many of us run). They make no claims to any more. However, the effects of the stated condition above are noteworthy and have enough effect that they continue to find there way on to production bikes and racers alike.

Soooooo, the argument that land based vehicles are never going to produce enough speed to make a ram air system (as the local injurkneers are thinking of them) viable is moot. It doesn't apply here as the OEM's aren't expecting to get any kind of "boost effect".

A good Ram Air system helps the engine maintain a full airbox, as much as that may be possible. Why do you think that when people talk about the ideal size of an airbox or plenum, it's normally a lot larger then the one that came with your car? It's becuase it's less likely to be sucked empty when one of those cylinders opens up and gulps down a ton of air.

Now if you can move a ton of air into the air box and maintain a condition as close to 0 vacuum as possible, is that not going to have a good effect on the engines performance?

Anyway, I am yet to hear a viable explanation for why the major Japanese and Italian manu's are building these systems if they are indeed junk. And for those of you that are tempted, you can't say it's for sales reasons. In the world of Win-on-Sunday-Sale-on-Monday, a BS gimmick (like ram air tubes with cone filters or turbonators) is not going to make it onto a bike that is run in SuperStreet, SuperStock, or even Superbike guise.

For those of you that are thinking about building one, do it. I'm going too. I'm going to because I believe (in other words, I'll know for sure after it's done) that the same benefit can be had at the turbine inlet that the N/A motorcycles are seeing at the airbox.

If you do, just take a look at what the motorcycle makers are doing before you do so. Don't take it from ghey ricers or sales guys at Pep Boys trying to move cheesy cone filters with tubes or electric fans inside.

[Hagar17]

A good Ram Air system helps the engine maintain a full airbox, as much as that may be possible. Why do you think that when people talk about the ideal size of an airbox or plenum, it's normally a lot larger then the one that came with your car? It's becuase it's less likely to be sucked empty when one of those cylinders opens up and gulps down a ton of air.

Empty your air box? Maybe if you were in space! maybe I'm wrong but the atmosphereric pressure is what fills the airbox and it is constant - only a turbo will increase that enough to make any performance gain.

[BDKR]

Empty your air box?

Of course it doesn't empty it, but it's certainly trying right? And based on the fact that boost gauge reads 20 in at idle, I'd say it's doing a good job.

[Hagar17]

remove the air box and see what the gauge reads..

[davidmacq]

I did see an excellent piece by a guy who decided the same thing after some good real-world testing:
http://www.karlsnet.com/mopar/ramair.shtml

He did quite a few real-world tests. He rigged up rigid tubes with a pressure sensor; if I recall he mounted them on his car somewhere. Took mesurements on wide-mouth funnel-type intakes and found that the outlet end was what determined the amount of pressure and of air flow. Size of "mouth" at the front end had absolutely no effect. The big mouth did nothing, as usual... (couldn't resist that one)

He also tested for pressure (or flow??) using straight ducts parallel to the direction of travel, and with various degrees of tilt and/or bend in the duct. Also tested corrugated duct vs. smooth duct. If you're thinking about ram air or cold air intake, you've got to read this guy.

Yes, I posted that link before. I think you got something wrong though. He measured different scoops and found that flow relates to the scoop size. Not the hole at the end of the scoop. Here are his words on it:

"The first experiment I ran was to figure out how restrictive different scoops were (based on geometry and area). I acquired several different scoops, and tested them with a High Power Turbo Honeywell fan and a strain gauge I made. All scoops were tested five times with three different air flow rates (to minimize error and variations from test to test). The results were all scoop geometries (even cones that had a larger inlet than outlet) all let through the same amount of airflow based on their area. From this experiment I concluded the only factor that matters for an intake scoop is the area of the scoop. This is contrary to what a lot of ram air manufacturers and some ram air gurus claim, a lot of them say that cone / wedge like scoops will 'draw in' more air than just a circle of the same area outlet, my research and experiment says no."

I take what he is saying is the area of the scoop is what matters. Scoop meaning the opening. In a round pipe that gets smaller the scoop would be the front? I'll email the guy about it. lol


The Inguneers made fun of that guy. lol



Oh well. This thread is pointless. Inguneers tend to think they are a little smarter than they are. LOL. Just read about some Inguneer telling people why some golf club had no score lines. Why he announced to strangers he was an Inguneer is unknown, but the golf club maker said he was full of crap.

And here we have Inguneers trying to relate to us, what we can see in the real world, but also trying to downplay what we see.

There are real world measurable benefits to ram air. Small though they are. lol. One Inguneer says negligible, the other says pull off your intake and you will be ahead of the game? lol.

Whatever. Keep benchracing you Inguneers!

[davidmacq]

remove the air box and see what the gauge reads..

Oh, so like Bongo you say if we didn't have intakes we wouldn't need RamAir, huh?

Fair enough, too bad we got that pesky AMM n crap like that.

Newest mods:

1. rip out intake
2. install 100 percent efficient intercooler, lol
3. ????????
4. profit/ go faster lol

Hey, if you want to argue about this more. I'm just sitting here bored. I emailed the guy at karlsnet too. LOL. Maybe he will chime in.

[pwschuh]

Yes, I posted that link before. I think you got something wrong though. He measured different scoops and found that flow relates to the scoop size. Not the hole at the end of the scoop.
<snip>
I take what he is saying is the area of the scoop is what matters. Scoop meaning the opening. In a round pipe that gets smaller the scoop would be the front?
No. He didn't word it very clearly but what he is saying is that the only thing that matters is the size of the hole at the back end of the scoop.

[davidmacq]

Yes, I understood what you were saying, but how can scoop area mean anything but the size of the opening of a scoop? Do we seriously think he considered whether 2 scoops with same opening, but different volumes would flow differently? Or for that matter, the exit size in the scoops.

Saddest part of all this is the Injuneers think they can model everything perfectly.

They trot out old calcs that explain a ram air can't be a turbo replacement because a close ended pipe in the wind will not build up pressure. Well gee, the turbo is helping clear out the intake anyway. We don't want any pressure to build up in the intake. We want the turbo to be supplied air and not have to work hard to get it.

As long as a .01 psi increase is kept in the intake, Ie, to the turbo, then that will cause the turbo to have to work less. Model that, mofos.

[BDKR]

remove the air box and see what the gauge reads..

:rofl: :rofl: :rofl: :rofl:

Holy crap that's dumb.

If you want to make it un-dumb, define the vehicle and it's attributes that we're removing the airbox from. Besides, if it was that simple, Kawis, Hondas, etc.... would still be running with no air boxes.

[Hagar17]

:rofl: :rofl: :rofl: :rofl:

Holy crap that's dumb.

If you want to make it un-dumb, define the vehicle and it's attributes that we're removing the airbox from. Besides, if it was that simple, Kawis, Hondas, etc.... would still be running with no air boxes.


"Of course it doesn't empty it, but it's certainly trying right? And based on the fact that boost gauge reads 20 in at idle, I'd say it's doing a good job."

no it was stated previously the gauge read something with the airbox a certain design/size - I simply said remove the air box and tell if the gauge (boost I believe it was) changes reading at all...

Here is a easy way to test ram air - tell me if you can blow up a balloon by holding the opening to the balloon to the wind and driving really fast. Put a huge scoop in front of it and see if that helps...LOL :rofl:

[mfpmax]

Actually, the purpose of that cone was to restrict air flow into the motor. At massively supersonic speeds they need to restrict the volume and reduce the speed of the air, or it will simply blow out the combustion. Flame can't travel upwind past a certain speed, I guess.

So those are sort of like the opposite of ram air.

Discovery Channel taught me that back in the 90s :lol:

[pwschuh]

Yes, I understood what you were saying, but how can scoop area mean anything but the size of the opening of a scoop? Do we seriously think he considered whether 2 scoops with same opening, but different volumes would flow differently? Or for that matter, the exit size in the scoops.

That's why I said he used poor terminology. He said 'scoop area' but he didn't mean scoop area. If you read carefully, what he meant was the area of the hole at the rear of the scoop. He was comparing (say) a 3" tube versus a scoop with a large opening but with a 3" hole at the back and said they were the same.

[Hagar17]

I think people confuse wind resistance (force on your hand being out a moving car's window) versus air pressure...

[JohnMc]

I think people confuse wind resistance (force on your hand being out a moving car's window) versus air pressure...
Yep, that's the PSI generated on your hand, multiplied by all the square inches on your hand. But the PSI generated is just that, and a scoop can't multiply that into higher PSI.

[brucepick]

Too bad the karlsnet.com guy wasn't crystal-clear on his findings re. cone/wedge shaped intakes. It looks like he did good work, and the rest of his page is pretty clear as to what he meant. Hopefully he'll answer that email he should be getting.

Anyway, I was all set to "build" - actually cut - a cold air semi-ram intake on my NA 245, '89 vintage. I'm hesitant to bash the filter with all that air, then rain and snow and even flying sand. So I'm holding off till I can think of a place to route some fat hoses to feed the normal intake ports on the stock air box.

The plan WAS to cut out the front face of the air box. It's about 3-1/2" X 10" or so. On the '89 U.S market 240, this is right behind the A/C condenser. On mine, duh, the AC is permanently off duty, and even with the condenser tubes in the way I still figure that's maybe a 5X-10X increase in intake area compared to the stock snorkel - plus, the air is "ramming" into it at road speed. Should be way better than the tiny stock intake snorkel.

But, I just recently had to buy a new (reconditioned) AMM, and I sure don't want to trash it with flying bits of paper filter and whatever, this coming winter. I think it might be a great design for someone in a relatively clean dry environment.

Would be nice to find a routing path for the 2 existing intake ports on the air box. A path to route some hoses or tubing so they are fed a good air supply. Without cutting any sheet metal - or at least not tooo much. I'm hoping for a way to pick up air behind the oval cutouts in the plastic/rubber air dam - with a fairly straight smooth path for the ducted air.

Any ideas?

[JohnMc]

Well, there might be more to an air box snorkel than you think. Air has mass, and like anything else with mass it has both inertia and momentum. Things that work against the way the intake valve opens, sucks air in, and then closes, making the air constantly stop and start. Bad for momentum, bad for flow. But if you get the volume of the intake tract just right, the air volume going in will be more constant, and actually help build up pressure waves slightly when the valves are closed, helping the air get moving when they open.

Really, I think for the most part sound waves are what we are talking about, although the actual movement of the air means there is more to it than just a simple sound wave - waves typically involve no permanent displacement of the medium. 'Tuned intake manifolds' really just try to get the air bouncing off the just closed intake valve to bounce back outwards, then reflect off something (other side of the plenum) and bounce back down the intake tract just in time to hit the intake as it opens. Obviously that back and forth trip always takes the same amount of time (speed of sound), so the length is tuned for a specific RPM, when the timing of the reflection matches the timing of the valve opening up.

Of course, that is all NA tuning hocus pocus, and probably has little to do with the more even uptake of air into a turbo inlet, and who cares too darn much about sound waves bouncing around in an intake manifold when you could just turn up the boost pressure a tiny bit and make a larger difference.

[davidmacq]

Remember an intake in a turbo or NA application needs to supply the engine or turbo with plenty of UNPRESSURIZED air. Let the turbo do the boosting you Inguneers. lol

[Hagar17]

Well, there might be more to an air box snorkel than you think. Air has mass, and like anything else with mass it has both inertia and momentum. Things that work against the way the intake valve opens, sucks air in, and then closes, making the air constantly stop and start. Bad for momentum, bad for flow. But if you get the volume of the intake tract just right, the air volume going in will be more constant, and actually help build up pressure waves slightly when the valves are closed, helping the air get moving when they open.

Really, I think for the most part sound waves are what we are talking about, although the actual movement of the air means there is more to it than just a simple sound wave - waves typically involve no permanent displacement of the medium. 'Tuned intake manifolds' really just try to get the air bouncing off the just closed intake valve to bounce back outwards, then reflect off something (other side of the plenum) and bounce back down the intake tract just in time to hit the intake as it opens. Obviously that back and forth trip always takes the same amount of time (speed of sound), so the length is tuned for a specific RPM, when the timing of the reflection matches the timing of the valve opening up.

Of course, that is all NA tuning hocus pocus, and probably has little to do with the more even uptake of air into a turbo inlet, and who cares too darn much about sound waves bouncing around in an intake manifold when you could just turn up the boost pressure a tiny bit and make a larger difference.

Air box Resonance!

http://motorcycleinfo.calsci.com/Airboxes.html

[davidmacq]

Why do almost all pro street drag cars have ram air? Think if we covered them the times would be the same?

[iThinkergoiMac]

No, their times would suck, but that's because if I understand it correctly the ram air intake is the ONLY intake...

[davidmacq]

Well I meant more disconnecting them, or like making them cowl induction for comparison.

[Hagar17]

I think on those cars with turbos and superchargers it would make some small difference (which in racing if it's enough to win it's a huge difference!) but on a regular na car no other mods almost nil.

Still it's fun to fab up stuff and make it go!

[barefoot]

Whatever. Keep benchracing you Inguneers!

Not sure what you're attempting to achieve by misspelling, but seriously dude, it just makes you look stupid.

Several of you are also demonstrating that you suck at the entire concept of pressure.

All I can say on the matter, having not done any experiments, is to quantify the amount of pressure theoretically available at the front of the car.

I say "theoretically available". It's similar to how a ball can theoretically bounce only as high as the point it was released from. There just isn't the energy available to make it bounce higher, unless you live in a cartoon. Likewise, there simply isn't the pressure available to "ram" any higher than the 0.5psi at 170 mph I mentioned earlier. It's engineering theory, you can call it benchracing if you like, but engineering theory is what makes cars work in the first place.

Again, back to the bouncing ball analogy, there are plenty of reasons why the ball isn't going to bounce back to the same height - and plenty of reasons why you'll get less ram air pressure than the theoretical maximum.

At aircraft speed...at serious drag car speed...at racing motorbike speed...ram air is real. At Volvo speed, don't waste your money.

tim

[Billiam500]

My $0.02

"ram Air" is complete BS. At street car speed, there is no way that air being "rammed" into the intake will significantly improve performance. take into account the restriction of the scoop(especially the ones on the POS Grand Am GT), throttle body, and the air filter, and you are left with nothing.

[BB-Q]

Here is a easy way to test ram air - tell me if you can blow up a balloon by holding the opening to the balloon to the wind and driving really fast. Put a huge scoop in front of it and see if that helps...LOL :rofl:[/QUOTE]

Found out when I was younger that it works with a condom @ 74mph:-P

Seemed like a good idea at the time

[davidmacq]

Not sure what you're attempting to achieve by misspelling, but seriously dude, it just makes you look stupid.

Several of you are also demonstrating that you suck at the entire concept of pressure.

All I can say on the matter, having not done any experiments, is to quantify the amount of pressure theoretically available at the front of the car.

I say "theoretically available". It's similar to how a ball can theoretically bounce only as high as the point it was released from. There just isn't the energy available to make it bounce higher, unless you live in a cartoon. Likewise, there simply isn't the pressure available to "ram" any higher than the 0.5psi at 170 mph I mentioned earlier. It's engineering theory, you can call it benchracing if you like, but engineering theory is what makes cars work in the first place.

Again, back to the bouncing ball analogy, there are plenty of reasons why the ball isn't going to bounce back to the same height - and plenty of reasons why you'll get less ram air pressure than the theoretical maximum.

At aircraft speed...at serious drag car speed...at racing motorbike speed...ram air is real. At Volvo speed, don't waste your money.

tim


I spell it Injuneer to illustrate your stupidity and hardheadedness. You sure a a tedious mofo. haha. Yah I used tedious because it is very unoriginal and pissed you off last time someone used it.

I concede all your points you wrote. I think it illustrates your hardheadedness very very well.

Noone is claiming ram air can make more than .5 psi. So get over it, and quit tearing down the 'straw man' GEEZ.

Intake's job is to supply the engine or turbo with air. Not build boost. That is why .5 psi is a stupid arguement. You are letting your edumacation make you look stupid. Quit trying to apply it to common sense stuff. NOONE IS ARGUING WITH YOU THAT A RAM AIR IS GOING TO CREATE BOOST. So get over it. K?

As that silly formula someone posted a long time ago proves, you can't create pressure even sticking a close ended pipe out in the wind. So tell me smart guy, why are you arguing that it can't be done when the end of the tube has a turbo sucking the air out faster than you can put it in.

NOONE IS ARGUING WITH YOU ABOUT THAT, AND THAT IS WHY YOU LOOK LIKE AN IDIOT INJUNEER.

REAL WORLD RESULTS. HOW CAN AN INJUNEER ARGUE WITH THEM? BY GETTING CONFUSED I GUESS. HOW SMART DO YOU HAVE TO BE TO TAKE OBSERVABLE REAL WORLD RESULTS AND TRY TO MODEL WHAT'S HAPPENING AND CALL BS. BY BEING NOT QUITE AS SMART AS ONE THINKS ONE IS I SUPPOSE. lol

[Unregistered]

REAL WORLD RESULTS. HOW CAN AN INJUNEER ARGUE WITH THEM? BY GETTING CONFUSED I GUESS. HOW SMART DO YOU HAVE TO BE TO TAKE OBSERVABLE REAL WORLD RESULTS AND TRY TO MODEL WHAT'S HAPPENING AND CALL BS. BY BEING NOT QUITE AS SMART AS ONE THINKS ONE IS I SUPPOSE. lol

Giving him the benefit of the doubt, maybe Dave's drunk.

[Billiam500]

Intake's job is to supply the engine or turbo with air.

Actually, the intake's job is to recieve the air that the turbo pressuizes., and contian the air that will be sucked into the engine so it's pressure or volume can be measured.
BTW, if you use "lol" in a technical post, any points you make will be ignored.

[davidmacq]

Actually, the intake's job is to recieve the air that the turbo pressuizes., and contian the air that will be sucked into the engine so it's pressure or volume can be measured.
BTW, if you use "lol" in a technical post, any points you make will be ignored.

WHY? LOL, you dislike acronyms? Yet, you use BTW? WTF? LOL! haha.

Actually I joke around, but I should say I don't doubt Tedium's mathmatical ability. Only how he is applying it.

As for intake, I mean intake preturbo. If you don't want to call that part of the intake, fine.



Here is a serious question. I grant that a ram air will not create pressure, but is that what we should be looking at?

Take an open ended 3 inch pipe. Have someone stick it out the window into the airflow. Whether it is open ended or not, we concede that it will not be pressurized whether it has a larger opening or not.

YET, HERE IS THE TEST. COMPARE THE 3 INCH PIPE IN THE WIND, TO ONE WITH A LARGER MEGAPHONE TYPE OPENING SAY 10 INCH FUNNELING DOWN TO THE SAME STYLE 3 INCH PIPE.

question: THE PRESSURE INSIDE THE PIPES WILL BE NEAR EQUAL, BUT WHAT ABOUT THE VELOCITY OF THE AIRFLOW?

I SAY ALL THIS TALK ABOUT PRESSURE IS A RED HERRING. TALK FORMULAS ALL YOU WANT, IT IS MISAPPLICATION OF YOUR MATHS. IN A TURBO APPLICATION. WHAT EFFECT WILL HIGHER INTAKE VELOCITY TO THE TURBO HAVE ON PERFORMANCE?

Negligable to be sure, but beating a dead horse talking about pressure is silly. Noone claims a big pressure increase. You engineers claim it is worthless by saying there is no pressure and leave it at that, but you don't try to explain the real world benefits either. Sounds like you decided before you pulled out your calculator.

[JohnMc]

I was out riding my bicycle, and a thought popped unbidden into my head, in regards to the resonance built into a normally aspirated engine's intake manifold. This is based upon the speed of sound, as the time it takes for a sound to bounce off the intake valve, out the runner, and reflect back to arrive at or soon after the valve reopens works is dependent not only on the timing of the valve reopening (or the RPM of the engine) but also the speed of sound, how long it takes that sound to travel back and forth. And the higher the air pressure, the lower the speed of sound is. Which made me wonder about the rpm tuning of a turboed car's intake manifold, it might be for a lower rpm than you'd think, especially once the boost has be raised.

Of course, this is a fairly worthless thought, because once you are turbocharging a motor anyhow you've got a much better way of cramming air in a cylinder than some little sound waves bouncing around.

[croovlov]

How about those NACA ducts that F1 and other engineered race cars use? I think their function is to ram air, that is icrease its density somewhat. Otherwise, wouldn't any intake naturally end up with air at below 14.7 due to turbulence etc.?

Carlo

[mikep]

If I remember my aviation folklore, NACA ducts were designed to get air into a body without causing (much) drag.

BTW, saying "nakka" is incorrect, despite what NASCAR says.. it's "N"."A"."C"."A".

[Volvoteen]

On a naturally aspirated engine, the intake simply uses the cars speed to "pull" in air right? I was wondering if that is different for a turbocharged car. In a turbo's case, doesn't the turbine make the intake system behave sort of like a vacuum, literally sucking in air more rapidly than in a naturally aspirated counterpart? Or is that air still flows regularly to the turbo and is then compressed? Only a question don't anyone go all crazy on me. Depending on your answer i may have another question

[mfpmax]

If I remember my aviation folklore, NACA ducts were designed to get air into a body without causing (much) drag.

BTW, saying "nakka" is incorrect, despite what NASCAR says.. it's "N"."A"."C"."A".

Better than people calling them NASA ducts on Ebay.

[iThinkergoiMac]

NOONE IS ARGUING WITH YOU THAT A RAM AIR IS GOING TO CREATE BOOST.
However, the very premise of ram air is that it's supposed to create boost, hence the whole reason of this thread and the reason of his post...

You should try sticking to the subject :rofl:

[JohnMc]

On a naturally aspirated engine, the intake simply uses the cars speed to "pull" in air right? I was wondering if that is different for a turbocharged car. In a turbo's case, doesn't the turbine make the intake system behave sort of like a vacuum, literally sucking in air more rapidly than in a naturally aspirated counterpart? Or is that air still flows regularly to the turbo and is then compressed? Only a question don't anyone go all crazy on me. Depending on your answer i may have another question
Well, on the N/A car I'd have to characterize that as a 'push' instead of a pull. It's a very slight push, and only at very high speeds. The rest of the time it's just a nice cold air supply, better than the hot air that's been through the radiator.

Now for a given turbo rpm, it is going to create a pressure differential between the inlet and outlet. The higher the pressure is at the inlet, the greater the outlet pressure will be as well. But that pressure differential is created by the power supplied by the exhaust system, and if a turbo had slightly less air pressure at the intake I suspect, given a set amount of energy by the exhaust, that it would just spin up a little faster until the energy from the exhaust matched the energy consumed by compressing air. I guess it would depend on how much of a partial vacuum you had, and what rpm the turbo's vaning was designed for if the higher speed would be less efficient or not. I'd tend to guess that a turbo is designed for a certain rpm range, and operating under or over that isn't efficient, resulting in less boost and higher intake temperatures.

But really, we are talking .5 psi at 170 mph, and much, much less at lower MPH. I doubt a turbo really cares too much if the air coming in the inlet is at 14.7 or 14.8 psi. The temperature of the air is a greater concern.

[iThinkergoiMac]

You mean 14.7 or 15.2?

[JohnMc]

You mean 14.7 or 15.2?
I wasn't giving the full 170 mph credit. Just fudging down to what you'd probably see at 80 - 100 mph. 14.7 is normal sea level atmospheric pressure.

[iThinkergoiMac]

oh, OK

[Volvoteen]

Well, on the N/A car I'd have to characterize that as a 'push' instead of a pull. It's a very slight push, and only at very high speeds. The rest of the time it's just a nice cold air supply, better than the hot air that's been through the radiator.

Now for a given turbo rpm, it is going to create a pressure differential between the inlet and outlet. The higher the pressure is at the inlet, the greater the outlet pressure will be as well. But that pressure differential is created by the power supplied by the exhaust system, and if a turbo had slightly less air pressure at the intake I suspect, given a set amount of energy by the exhaust, that it would just spin up a little faster until the energy from the exhaust matched the energy consumed by compressing air. I guess it would depend on how much of a partial vacuum you had, and what rpm the turbo's vaning was designed for if the higher speed would be less efficient or not. I'd tend to guess that a turbo is designed for a certain rpm range, and operating under or over that isn't efficient, resulting in less boost and higher intake temperatures.

But really, we are talking .5 psi at 170 mph, and much, much less at lower rpms. I doubt a turbo really cares too much if the air coming in the inlet is at 14.7 or 14.8 psi. The temperature of the air is a greater concern.
Makes since to me. So in the natural progression of this conversation; in chemistry there is a law that says a reaction can only be as great as its biggest limiting factor(or smallest variable)...for instance attach a firehose to a sink faucet and no matter how much water is provided by the firehose, the faucet cannot expend anymore water than it could when it was attached to regular piping. With this in mind...wouldnt the best source of performace come from making the turbo connect directly to the outside air with no intake pipes at all. I know its not realistic, but the point is that no matter how big your intake or ram air scoop or whatever, the turbo can still only "take in as much as it can take in." As long as you supply the turbo with its required or standard amount of air, it will function the same as when you attach a ram air intake to it the size of Texas.

[casioqv]

I doubt that "ram air" offers any actual benefits at legal speeds, but I also think that it COULD add benefit without creating boost. Boost pressure is usually measured with gauge pressure (pressure relative to the ambient atmospheric pressure). In all N/A cars the pressure at the intake valve (or turbo inlet on a turbocharged car) is much lower than the ambient atmospheric pressure due to the engines vacuum. If this pressure were increased slightly due to ram air then the amount of air entering the cylinder would be greater, even if still below 0psi gauge pressure. This is the same reason why air filters, intake diameters, etc. improve power output (but usually much less than people think/expect).

Also- The statement earlier about how the air velocity is more important than the pressure makes no sense. At a fixed engine displacement, RPM, temp, and air pressure the velocity and intake pressure will be directly proportional (because of PV=nRT).

However, the very premise of ram air is that it's supposed to create boost, hence the whole reason of this thread and the reason of his post...

You should try sticking to the subject :rofl:

[davidmacq]

However, the very premise of ram air is that it's supposed to create boost, hence the whole reason of this thread and the reason of his post...

You should try sticking to the subject :rofl:


It is the premise? I didn't know it had a premise other than better performance.

Noone is arguing ram air won't do more than .5 psi, etc, but the injuneers say it is pointless because of this ignoring real world results. It is patently silly, and a straw man, especially with a turbo.

Volvoteen, you are correct. On a factory volvo, when you are pushing 12 or 13 psi, the turbo will create an ever so slight vacuum in the pre-turbo intake. At this range the turbo is already out of it's efficiency range. It is heating up the air more than a larger turbo would. The intercooler normally takes care of this. The stock intercooler isn't especially efficient though, so it removes maybe 70 percent of the added heat, according to cpt. bondo.

A ram air isn't going to increase boost to any noticable degree, as the engineers have explained. What it will do is get air to the turbo quicker, (faster throttle response) and cause the turbo to less work hard, (superheating the air less) which in turn puts less work on the intercooler.

So yes, you grasped from the start that a turbo is going to be sucking in air through the intake. Operate it out of it's efficiency range, with a poorly designed intake, and ram air will increase the intake air velocity. (Less vacuum) And what do you know, we never created any boost with the ram air.

You can talk about perfectly sized turbos, and 100 or even 90 percent efficient intercoolers till your blue in the face.

Fact: Ram air on factory volvo increases performance. Injuneers good job crushing false premises of ram air.

[Volvoteen]

Beautifully put davidmacq...I'm glad someone saw where i was going with that. The point is...do what must be done to make sure that the turbo is not "deprived" of air. If the intake is not supplying all the air that the turbo can take in at any given time than, yes, a ram air system that allows for more air to enter the intake is just what the doctor ordered. The whole purpose of an intercooler, at all, is to correct what restricted airflow causes i.e. heated air. Summary: give the turbo all it can take in; the turbo will give you all it can dish out.

[davidmacq]

I doubt that "ram air" offers any actual benefits at legal speeds, but I also think that it COULD add benefit without creating boost. Boost pressure is usually measured with gauge pressure (pressure relative to the ambient atmospheric pressure). In all N/A cars the pressure at the intake valve (or turbo inlet on a turbocharged car) is much lower than the ambient atmospheric pressure due to the engines vacuum. If this pressure were increased slightly due to ram air then the amount of air entering the cylinder would be greater, even if still below 0psi gauge pressure. This is the same reason why air filters, intake diameters, etc. improve power output (but usually much less than people think/expect).

Also- The statement earlier about how the air velocity is more important than the pressure makes no sense. At a fixed engine displacement, RPM, temp, and air pressure the velocity and intake pressure will be directly proportional (because of PV=nRT).

I think you are getting a grasp of how ram air can affect performance without creatiing boost.

As for the velocity arguement. Remember the Injuneers have conceded very slight pressure increases. So...with a slight pressure increase velocity can be increased?

In a megaphone type cone, either the air goes around the cone, through the cone, (thus increasing velocity) or creates pressure. Any other options?

You sound like you know some things. Haven't heard about increasing velocities by going to smaller diameter pipes?

Not sure if water directly translates to air, fraid it doesn't, but everyone has experienced a shower with poor water pressure?

The funniest part of all this I think, is that we care more about how much and how fast air is being supplied to the turbo, not whether we are creating boost. Actually wouldn't the ram air have to outpeform the turbo to create boost anyway? The turbo will be pulling in are at least as fast as the intake can provide it.

This is all splitting hairs and nitpicking anyway. They have conceded the points already.

I'm sorry engineers, I didn't know people actually thought the premise of ram air was to create boost, like a hobo turbo.

[BDKR]

I have to say that reading back over all of this is funny like funny is going out style. It's allmost as funny as the "What makes a turbo spin" threads (ooops, I said it! :rofl: ). If laughing is healthy, then I say keep it up. ;-)

[Billiam500]

WHY? LOL, you dislike acronyms? Yet, you use BTW? WTF? LOL! haha.


Here is a serious question. I grant that a ram air will not create pressure, but is that what we should be looking at?

Take an open ended 3 inch pipe. Have someone stick it out the window into the airflow. Whether it is open ended or not, we concede that it will not be pressurized whether it has a larger opening or not.


Negligable to be sure, but beating a dead horse talking about pressure is silly. Noone claims a big pressure increase.
Show me where I said that I didn't like acronyms. Than tell me whay beating a dead horse is silly yet all of your posts on this page say, in one way or another, that ram air doesn't create boost. I'm pretty sure everone agrees that it doesn't make any noticable boost.

[davidmacq]

LOL, is an acronym. If everyone agrees they don't create boost, why do Injuneers pull out high maths to prove it to us? LOL

[Julian265]

I have to say that reading back over all of this is funny like funny is going out style. It's allmost as funny as the "What makes a turbo spin" threads (ooops, I said it! :rofl: ). If laughing is healthy, then I say keep it up. ;-)
Just because you have read and maybe even understood the fifty other threads on this topic doesn't mean these guys have. And that turbo thread had some good questions and answers, and some jerks poking fun without helping at all.

[Volvoteen]

Okay,wow you guys. Is ram air a myth??? Yes and no. In regard to increased boost pressure, yes. The boost pressure gained by the speeds that are obtained in even vigorous road driving are negligible at most. Does that mean that ram air filters are not necessary? Not entirely. If adding a ram air system means that you are giving the turbo a "full breath of air" or allowing it all the air that it can compress at any given time, than yes, the ram air filter is useful. BUT! If the intake is restricted by small hoses leading to the intercooler(and/or turbo) than nothing can be done to increase that performance unless there is found, a way that can widen these hoses or increase the airflow that they themselves provide the turbo. It comes to one essential point. The most efficient way to produce power, is to produce airflow. The engine is only as good as the air it takes in, and also only as good as the air it is CAPABLE of taking in, wether naturally aspirated or turbocharged; or even supercharged for that matter. The question is not by which means to feed the turbo or engine, but with whatever way you are feeding it, is it enough to fill that engine/turbo's capacity for air? End of story

[BDKR]

Just because you have read and maybe even understood the fifty other threads on this topic doesn't mean these guys have. And that turbo thread had some good questions and answers, and some jerks poking fun without helping at all.

Dude, please don't take offense here. I wasn't intending to say that people are stupid for saying aything here. What makes this thread funny is the interchange amongst some of us. For David, Tedium, 'Bondo, and I, there is a recent history of squabbling on this topic that it's totally funny in retrospect. Also the crap from Bertiebandit about how he held a condom out the window and blew it up. :rofl: C'mon, that ain't funny?

My apologies if I offended you.

[BDKR]

Okay,wow you guys. Is ram air a myth??? Yes and no. In regard to increased boost pressure, yes. The boost pressure gained by the speeds that are obtained in even vigorous road driving are negligible at most. Does that mean that ram air filters are not necessary? Not entirely. If adding a ram air system means that you are giving the turbo a "full breath of air" or allowing it all the air that it can compress at any given time, than yes, the ram air filter is useful. BUT! If the intake is restricted by small hoses leading to the intercooler(and/or turbo) than nothing can be done to increase that performance unless there is found, a way that can widen these hoses or increase the airflow that they themselves provide the turbo. It comes to one essential point. The most efficient way to produce power, is to produce airflow. The engine is only as good as the air it takes in, and also only as good as the air it is CAPABLE of taking in, wether naturally aspirated or turbocharged; or even supercharged for that matter. The question is not by which means to feed the turbo or engine, but with whatever way you are feeding it, is it enough to fill that engine/turbo's capacity for air? End of story

Good post.

That said, I think this pictue is fitting. Just replace OT with Ram Air Myth and you get the picture. LOL.
http://spams-ukwildcatbasketball.com/deadhorse.mbe.gif

[Volvoteen]

For anyone else...if you dont think this myth has been busted...refer to the last post on page four of this thread. Thank You.(LOL)

[Volvoteen]

Good post.

That said, I think this pictue is fitting. Just replace OT with Ram Air Myth and you get the picture. LOL.
http://spams-ukwildcatbasketball.com/deadhorse.mbe.gif
Hahahahaha....:lol:

[davidmacq]

That mean this is done? :( LOL. I wanted to hear about the Mathmaticks of Velocity from the experts!

[Volvoteen]

Hey what do I know...I'm only 17. :)

[Julian265]

Dude, please don't take offense here. I wasn't intending to say that people are stupid for saying aything here. What makes this thread funny is the interchange amongst some of us. For David, Tedium, 'Bondo, and I, there is a recent history of squabbling on this topic that it's totally funny in retrospect. Also the crap from Bertiebandit about how he held a condom out the window and blew it up. :rofl: C'mon, that ain't funny?

My apologies if I offended you.
Point taken, i read it a different way... :)

[davidmacq]

What's funny, like he said above. We went through this a couple months ago. Now someone drug up this old thread. LOL. Course they had to throw some punches at the old horse again.

Just so happens tonight I was reading Hotrod type magazine article about exhausts, and it was talking about pressures and velocities!

Seems like it makes TONS more sense to talk about velocities in this case than pressures.

I really would like to hear more knowledgeable peoples thoughts on that, because face it. We aren't arguing about the results of ram air, only the theory. We all know it only gives slight increases in certain situations. Well the people that argue in these threads anyway.

So I wonder. A megaphone cone shape doesn't build pressure, but can anyone deny that going from a large opening to a smaller opening WILL increase velocity? No seriously. I ask the engineers in all seriousness.

I respect math and engineering, but I also realize that most mistakes they make are based on misapplying the math. In physics to me making the free body diagram mirror reality was hard!

[Julian265]

I think you will find that speed and pressure are linked...

So I wonder. A megaphone cone shape doesn't build pressure, but can anyone deny that going from a large opening to a smaller opening WILL increase velocity? No seriously. I ask the engineers in all seriousness.

Sure, for a given airflow reducing to a smaller pipe will increase airspeed... So??? That doesn't mean that any more will flow through the funnel when placed in an airstream, compared to a straight pipe.

[davidmacq]

I think you will find that speed and pressure are linked...



Sure, for a given airflow reducing to a smaller pipe will increase airspeed... So??? That doesn't mean that any more will flow through the funnel when placed in an airstream, compared to a straight pipe.


Well you see, that is where having a big scoop attached to a smaller pipe that routes through all the little tight spots to the turbo comes in. We can't have mandrel bent 4 inch pipes easily running to the turbo. So big scoop, into smaller pipe to get the air quicker to the turbo. That is what we are talking about.

Especially if you could say that a factory system just has a 2 inch intake pipe, and a ram air adds a 12 inch funnel to increase intake velocity. That would explain what a ram air's job is without creating boost.

Wasn't the whole point of their arguements that you can't create pressure? On the other hand if you take a 1 square foot cross section pipe and reduce to half it's size, the velocity will go up, but the pressure will not. True? I mean I'm not an engineer, but 270 kph only can make .5 psi. What I mean to say is that velocity will go up more than pressure. A simple mind might think for a moment that if velocity doubles then so would pressure, but I think that would be a very grave error.

When you stick your arm out a window, aren't you just feeling the force of the wind derived from it's mass and velocity? If you want to feel pressure, you dive down 30 ft underwater and you feel the increased pressure all the time. Not claiming water and air act the same in these cases, but it seems like they have explained well how air isn't pressurized easily.

I think that is key, while the air can't be pressurized it can be sped up?

[davidmacq]

To continue the thought, a turbo is pulling in a half to a WHOLE atmosphere or more than a N/A app. Intakes on N/A's have a hard enough time. So you can bet the turbo is doing some sucking on that intake. Sure it would be nicer to have a huge mandrel bent intake snorkel, or no intake at all if you have a very highly efficient intercooler.

That is why with math and perfect scenarios you can say ram air is almost pointless, yet you can still take a stock volvo turbo and put ram air on it and get some improvements.

It is in these margins that we argue, and find our results.

[Julian265]

Damn, i just can't keep myself from posting.. oh well, here goes.

Dave, from my interpretation of your posts I think you need to take a step back and look at the 'order' (cause/effect) of what happens between air intake and engine, and also the terminology of pressure. (sorry for the lecture, just trying to help)

Regarding pressure -
There are two types of pressure people are referring to in this thread - absolute pressure, that is the pressure at one point; and also a pressure difference between two points.

Stating an absolute pressure says absolutely nothing about flow rate or speed.
A pressure difference may be used to quantify either the 'force' that makes a fluid flow between two points, or the resistance between two points. (it works just like voltage in an electric circuit)
When vacuum is mentioned, it refers to the lower pressure at one point compared to another. It does not mean "negative pressure" - it means a negative pressure difference, looking from the higher pressure point.

When you stick your arm out a window, aren't you just feeling the force of the wind derived from it's mass and velocity?yes, the force difference between the front and back sides of your arm, due to the pressures over the front and back of your arm's area, due to the flow disruption and mass and speed of the air flow...

You can't say that ram air increases air speed in the intake thus increasing power... it's just too simplistic.

Back to basics - any flow of fluid is caused by a pressure difference between two points. In an NA engine, air flows into the cylinder when the piston moves down, due to the relative vacuum created compared to atmospheric pressure. In a turbo engine, more air flows into the cylinder due to the larger pressure difference between the cylinder and compressed inlet air.

The flow rate of air is also determined by the resistance between the two points. Ignoring resonances and throttling, the pressure difference in an NA engine is pretty much fixed, whereas for a turbo the pressure difference increases with boost. A given inlet design will have a set resistance, leading to a certain flow rate. It is this flow rate, through the pipes of various sizes that determines inlet velocity.

[davidmacq]

On a related side note, I've read about planets with 400 mph winds that won't even knock you over, because the atmosphere is so thin. Mars?

Sounds like same reason that causes a ram air to be unable to pressurize an intake more than .5 psi, also illustrates just how hard a turbo has to suck to get 15 psi through the intake. Eh? Eh?

[davidmacq]

Damn, i just can't keep myself from posting.. oh well, here goes.

Dave, from my interpretation of your posts I think you need to take a step back and look at the 'order' (cause/effect) of what happens between air intake and engine, and also the terminology of pressure. (sorry for the lecture, just trying to help)

Regarding pressure -
There are two types of pressure people are referring to in this thread - absolute pressure, that is the pressure at one point; and also a pressure difference between two points.

Stating an absolute pressure says absolutely nothing about flow rate or speed.
A pressure difference may be used to quantify either the 'force' that makes a fluid flow between two points, or the resistance between two points. (it works just like voltage in an electric circuit)
When vacuum is mentioned, it refers to the lower pressure at one point compared to another. It does not mean "negative pressure" - it means a negative pressure difference, looking from the higher pressure point.

yes, the force difference between the front and back sides of your arm, due to the pressures over the front and back of your arm's area, due to the flow disruption and mass and speed of the air flow...

You can't say that ram air increases air speed in the intake thus increasing power... it's just too simplistic.

Back to basics - any flow of fluid is caused by a pressure difference between two points. In an NA engine, air flows into the cylinder when the piston moves down, due to the relative vacuum created compared to atmospheric pressure. In a turbo engine, more air flows into the cylinder due to the larger pressure difference between the cylinder and compressed inlet air.

The flow rate of air is also determined by the resistance between the two points. Ignoring resonances and throttling, the pressure difference in an NA engine is pretty much fixed, whereas for a turbo the pressure difference increases with boost. A given inlet design will have a set resistance, leading to a certain flow rate. It is this flow rate, through the pipes of various sizes that determines inlet velocity.


Lectures are fine, but I knew all of your points.

Are fluid laws and gas laws the same?

ANY FLOW OF FLUID IS CAUSED BY PRESSURE DIFFERENCE? What about momentum?

Are you saying you can't feel the mass of wind?

I think you are feeling the inherent mass and density of the wind when you put your hand out. Anyway it's only .01 psi of pressure when we are going 30 mph right? lol

That is all nitpicking math and details anyway.


As for the analogy about ram air and increasing velocity. I simplified it on purpose so we could discuss it.

Forget a ram air. I'm talking a megaphone type cone connected to a hose. The decreasing diameter will increase the velocity of the air passing through it. True or not?

It's silly to talk about absolute pressure, we all I think understand that we don't need to check the barometer to talk about this. Or that we mean a true vacuum when we talk about negative pressure. LOL

So you can't pressurize water right? So what do you feel when you riding in a boat and stick your hand in the water? The pressure on your hand, or the mass and velocity of the water passing by?

P.S. I never said that a ram air creates POWER by increasing air velocity in an intake, it can only make a turbo more efficient and responsive in certain situations.

[davidmacq]

The flow rate of air is also determined by the resistance between the two points. Ignoring resonances and throttling, the pressure difference in an NA engine is pretty much fixed, whereas for a turbo the pressure difference increases with boost. A given inlet design will have a set resistance, leading to a certain flow rate. It is this flow rate, through the pipes of various sizes that determines inlet velocity

Keep it straight, we are only talking about the intake preturbo in regards to ram air.


Yes, yes yes, thank you. A given intake will have a inlet velocity, etc, etc, and when we put a large scoop on the intake to collect more air we increase velocity without increasing pressurization noticably.

We have all experienced wind increasing velocity when it passes through a small area right?

[Julian265]

ANY FLOW OF FLUID IS CAUSED BY PRESSURE DIFFERENCE? What about momentum? Momentum is due to the movement of the fluid, caused by the pressure difference. No pressure difference, no flow, no momentum. Chicken and egg.

Are you saying you can't feel the mass of wind? no.

Forget a ram air. I'm talking a megaphone type cone connected to a hose. The decreasing diameter will increase the velocity of the air passing through it. True or not?Yes, for a given flow rate. The fact that you are reducing the pipe diameter does not increase flow rate in the way you are thinking. The air speed at the compressor inlet is fixed by the diameter of the pipe IT is in.... not that before it. The flaring of the inlet does not increase flow rate by increasing speed.... there are other reasons that i don't pretend to understand.

So you can't pressurize water right? So what do you feel when you riding in a boat and stick your hand in the water? The pressure on your hand, or the mass and velocity of the water passing by? You can pressurise water. You can't *noticeably* compress it. In still water you feel the increasing hydrostatic pressure as you put your hand deeper. In moving water you feel the force/pressure difference between one side and the other.

P.S. I never said that a ram air creates POWER by increasing air velocity in an intake, it can only make a turbo more efficient and responsive in certain situations. ok.

Yes, yes yes, thank you. A given intake will have a inlet velocity, etc, etc, and when we put a large scoop on the intake to collect more air we increase velocity without increasing pressurization noticably. No, you won't collect more air with a scoop, given we alread have a half decent inlet.

[davidmacq]

Momentum is due to the movement of the fluid, caused by the pressure difference. No pressure difference, no flow, no momentum. Chicken and egg.



Oh, so you forget the momentum of the air relative to your moving car, that is crashing into the ram air?

I think we can agree to disagree.



When I talk about flow rate, given how hard it is to pressurize air in an intake with ram air and such, I'm talking about the air speed passing through.

I fully understand you saying a cone will not gather more air and will not increase velocity of said air as it the cone gets smaller, but I disagree with you. That is why I asked for a scientific refutation of INCREASED VELOCITY, like one given for INCREASING PRESSURIZATION.

Now I don't claim gas and fluid laws to be the same, but have you never witnessed a shower head putting out a more forceful spray as a result to switching to a smaller shower head?

Basically you are just saying you are wrong to everything I said. Which is fine. I disagree.



Given that increased atmospheric pressure increases the mass of the air. I think you are feeling the mass of wind. You think you would feel the wind if it had no mass? What is the formula to calculate force again?

Noticeably compress water? Whatever, sounds like you basically agree with that. Won't you find if you go 10 atmospheres deep in the ocean that you will feel the weight of all the water over you, but the water will not occupy an appreciably smaller space than before.


Anyone know how far below sea level in air one would theoretically have to go before getting too two atmospheres? Basically I'm talking about going down a mineshaft, not underwater. Interesting concept.

[BB-Q]

Dude, please don't take offense here. I wasn't intending to say that people are stupid for saying aything here. What makes this thread funny is the interchange amongst some of us. For David, Tedium, 'Bondo, and I, there is a recent history of squabbling on this topic that it's totally funny in retrospect. Also the crap from Bertiebandit about how he held a condom out the window and blew it up. :rofl: C'mon, that ain't funny?

My apologies if I offended you.

Hey, that wasn't crap- it was true! looked like a 3' windsock. Try it if you don't believe me!:-P

[Julian265]

Oh, so you forget the momentum of the air relative to your moving car, that is crashing into the ram air? to tell the truth, i didn't think about the case of still air and moving object... but anyway, i guess you can explain the pressure/force/whatever using either momentum or pressure.

I fully understand you saying a cone will not gather more air and will not increase velocity of said air as it the cone gets smaller, but I disagree with you. That is why I asked for a scientific refutation of INCREASED VELOCITY, like one given for INCREASING PRESSURIZATION.I'm saying reducing the pipe diameter will speed the fluid up, but gather no more.

Now I don't claim gas and fluid laws to be the same, but have you never witnessed a shower head putting out a more forceful spray as a result to switching to a smaller shower head?This is not due to increased mass flow, but increased speed. The flow rate through your shower head is determined by the available pressure, and resistance in the pipes, making the resistance change due to changing the shower head negligible. Hence, the flow rate will be the same regardless of the shower head you use. So a shower head with less/smaller holes will have faster water coming out of it (mass conservation*) making it seem more forceful, which it is. But believe me, there is definately NO MORE water coming out of the smaller shower head than the big one. It's just coming faster out of a smaller area.

BTW gas/air is a fluid.

Given that increased atmospheric pressure increases the mass of the air. I think you are feeling the mass of wind. You think you would feel the wind if it had no mass? What is the formula to calculate force again?You're right, you wouldn't feel the wind if it had no mass. The formula for force is dependent on the pressure difference between front and back surfaces, and you're right, has density in it.

I think we're using different words to explain the same thing here:

Think about this... Though we may not feel it, we are being hit by many air molecules each second. Put your hand in water, and you can feel the pressure - it gets hit by many, many more molecules (this hitting and bouncing off is what we call pressure). The increased pressure of water is due to the increased density compared to air (more particles of more mass per volume). In still conditions you don't get pushed around by the pressure, because it is acting on all sides. When fluid is flowing around an object, a given amount of particles are bouncing off the front of it. Yet behind it, less particles are present, and less bounce off it (maybe due to their momentum trying to carry them away). We call this a difference in pressure, and as you were saying, more momentum is given up to the front side of the object than the back, causing a force, simply due to more particles bouncing off the front.

Noticeably compress water? Whatever, sounds like you basically agree with that. Won't you find if you go 10 atmospheres deep in the ocean that you will feel the weight of all the water over you, but the water will not occupy an appreciably smaller space than before. Pressurisation is different to compression. Double the pressure of air and it will occupy half the original volume (it's compressed). Double the pressure of water and you won't notice the change in volume (it's basically not compressed).

Anyone know how far below sea level in air one would theoretically have to go before getting too two atmospheres? Basically I'm talking about going down a mineshaft, not underwater. Interesting concept.hydrostatic pressure = density*gravitational force per mass * height. (rho*g*h). For two atmospheres (~200,000 Pa): 200,000=1.2*9.8*h, so h = ~17 km, using close but approximate values.

* Mass conservation - if you decrease the area which a fluid flows through, it must flow faster in order to keep the same mass flow rate.

[davidmacq]

Yes, we seem to be coming to same conclusion from different directions. I was saying start with a large pipe, (ram air) and go to a smaller pipe to increase speed of the air. Sorry I use speed velocity pretty much interchangably. A large opening will gather so much air, and going smaller pipe will speed that same amount of air up.

Same with the shower head. Can you relate water entering shower head is like air entering the ram air scoop. Momentum/force is causing the air to enter the large scoop, then is being sped up when it enters the smaller volume pipe. The scoop determines how much air is collected, and how much smaller the pipe is determines how much is sped up.

_________
******* \_______
********________turbo
________/

* = air, and something to correct the formatting.

Like so. Doesn't the large pipe gather the air and the smaller tube speed it up?



As for feeling the pressure on your hand, if you want to look at it that way I guess I could buy it. Slap a table you feel the 'pressure' of the particles on your hand. Just not used to thinking of any feelings from touching, hitting things, etc, as pressurization/compression.

17km huh? That's pretty deep.

Now I wonder how fast air in an intake must be traveling in preturbo side to supply the turbo with 15 psi of boost. Bet that is a hard calculation. Even giving the turbo, engine, etc easy volumes, speeds, to calculate. Definately seems it would be faster than in a N/A app.

[BDKR]

Hey, that wasn't crap- it was true! looked like a 3' windsock. Try it if you don't believe me!:-P

Actually I do believe you. It was a poor choice of words on my part. I just thought the fact that you actually did was hilarious.

[barefoot]

Now I wonder how fast air in an intake must be traveling in preturbo side to supply the turbo with 15 psi of boost. Bet that is a hard calculation.

Not particularly hard - it just relies on the (bizarre at first) property that pressure can be converted to velocity and velocity can be converted to pressure.

pressure = 1/2 * density * velocity^2

Let's call 15psi ~100kPa ~ 1atm.

so, 100k = 1/2 * 1.2 * v^2
v^2=41.67k = 41667
v=204 m/s
=740km/h
=450mph

What you're saying above about velocity increasing as you narrow down the "funnel" intake is quite true, but the wierd thing is that increasing velocity will decrease pressure.

That's how carbeuretters work. "Squeeze" the intake air through a restriction; the pressure drops because the velocity increases; this low pressure sucks fuel into the airflow. The airflow expands after the restriction and recovers pressure.

So, with your funnel intake - the faster you get the air going in the intake, the lower its pressure will be (but you can expand it later to slow the air down and get some pressure back) - but the pressure upstream will be high, as the air is blocked up "trying" to get into the hole. If the pressure is high, air will just flow around the funnel intake and not go in at all.

tim

[Hagar17]

Not particularly hard - it just relies on the (bizarre at first) property that pressure can be converted to velocity and velocity can be converted to pressure.

pressure = 1/2 * density * velocity^2

Let's call 15psi ~100kPa ~ 1atm.

so, 100k = 1/2 * 1.2 * v^2
v^2=41.67k = 41667
v=204 m/s
=740km/h
=450mph

What you're saying above about velocity increasing as you narrow down the "funnel" intake is quite true, but the wierd thing is that increasing velocity will decrease pressure.

That's how carbeuretters work. "Squeeze" the intake air through a restriction; the pressure drops because the velocity increases; this low pressure sucks fuel into the airflow. The airflow expands after the restriction and recovers pressure.

So, with your funnel intake - the faster you get the air going in the intake, the lower its pressure will be (but you can expand it later to slow the air down and get some pressure back) - but the pressure upstream will be high, as the air is blocked up "trying" to get into the hole. If the pressure is high, air will just flow around the funnel intake and not go in at all.

tim

I thought the engine will suck air in much faster than the speed of the air rushing by the vehicle - thus we need turbos to provide boost....right? :-P

[davidmacq]

I thought the engine will suck air in much faster than the speed of the air rushing by the vehicle - thus we need turbos to provide boost....right? :-P

Yep, I can agree with that. We know ram air doesn't make boost.

Thanks Tedium that was interesting. The intake I was talking about theoritically would be like 3 inch from turbo to the ram air, and the ram air would be like the equivalant of a 8 inch pipe or something.

I assume the pressure drop isn't as great as the velocity increase. Ie, double velocity doesn't half the pressure. Hmm, I guess you could use that same formula if you turned it around to calculate the pressure drop?

Yay, we are in Bernoulli's area today. Yesterday we visited Helmholz. lol.

Bernoulli Effect

For horizontal fluid flow, an increase in the velocity of flow will result in a decrease in the static pressure. The equation describing this effect is known as Bernoulli's law. The most practical example of this is in the action of an airfoil. The shape of an airplane wing is such that air flowing over the top of the wing must travel faster than the air flowing under the wing, and so there is less pressure on the top than on the bottom, resulting in lift.

[mikep]

I thought the engine will suck air in much faster than the speed of the air rushing by the vehicle - thus we need turbos to provide boost....right? :-P
If a car is going 60mph, it is going 5,280 fpm.
If a scoop is able to provide a square 1 foot opening, it can scoop 5,280 cfm.
If an NA Volvo needs more than 300cfm at that speed I am a gelding.

[Hagar17]

If a car is going 60mph, it is going 5,280 fpm.
If a scoop is able to provide a square 1 foot opening, it can scoop 5,280 cfm.
If an NA Volvo needs more than 300cfm at that speed I am a gelding.

If it were a pump that compressed the air (pressurized it) this would be true - but the air will not compress that easily it will simply blow past and around the scoop. Again try and hold a balloon out your window with a big sccop in front of it and tell me how fast you need to go to fill it up. :-P

[davidmacq]

An intake isn't a small balloon made of rubber. As was mentioned earlier someone stuck a condom out the window and blew it up, so I don't see any points being made here. A scoop and intake are rigid and aren't resisting the air entering it. In fact it isn't even a close ended system.

Why do you trot out ignorance again and make a tongueface?

[Neil Peart]

Ram Air's only benefit is the fact (a roughly insignificant one at that) you are getting slightly cooler air.

I have Ram Air, its called a turbo... works great!

you too! :lol:

turbo+intercooler=all the damn ram-air I want.

[BDKR]

you too! :lol:

turbo+intercooler=all the damn ram-air I want.

C'mon Neil! That only applies downstream of the turbo. I suspect you may be suprised at how in-effecient your inlet tract is upstream of the compressor.

[iThinkergoiMac]

An intake isn't a small balloon made of rubber.
Uhhhh, no it isn't... But he said put a scoop in front of it... The balloon would measure how much the scoop is compressing air...

[RYRY745]

I totally agree with neil turbo= all the damn ram air i want...

Now tell me again how ram air doesnt help on a two stroke gp bike??

[davidmacq]

Uhhhh, no it isn't... But he said put a scoop in front of it... The balloon would measure how much the scoop is compressing air...

No, I think he just said hold a balloon out a window. Very scientific. Would all depend on the strength of the rubber. Totally meaningless. Geez.

[BDKR]

I totally agree with neil turbo= all the damn ram air i want...


That's not actually ram air, it's air that's been compressed.

A quick question here.... Do you guys think that a turbo charged engine is some sort of closed system? One where concern only need be given from the compressor outlet on? And therefore inlet design upstream of the compressor is not important?

Or is it really true that a turbo engine, just like any engine, is a system? A system in that an in-efficiency at some point will most likely have a larger effect further downstream.

Or have you guys not really read this thread all the way through and are still thinking that we're talking about some kind of boost effect like a turbo or super charger? If that's the case, go sit in the corner with the cute little pointed hat.

[Hagar17]

An intake isn't a small balloon made of rubber. As was mentioned earlier someone stuck a condom out the window and blew it up, so I don't see any points being made here. A scoop and intake are rigid and aren't resisting the air entering it. In fact it isn't even a close ended system.

Why do you trot out ignorance again and make a tongueface?

My point was a very large scoop and a very fast car would be needed to generate enough pressure to blow up a balloon. The way the ram air people go on about it - is it's like forcing more air into the intake - I believe the engine will suck in air much faster than what will be forced into it by way of moving air over the vehicle except in extreme applications such as high speed racing and aircraft. Most of us here I don't think will get that benefit. But again I say to each their own and fab away on scoops and cowlings to grab all the air intake you want! :-P

As for the tongue face I am just a goofy bastard.

[davidmacq]

As Tedium calculated the intake velocity at 15 psi is 450mph I think a little help for the intake isn't out of the question. Just like you say the engine and turbo is sucking air out of the intake. Ram just tries to help keep air in the intake. Not compress it.

Geez, 450mph that's close to the speed of sound!

[BDKR]

But again I say to each their own and fab away on scoops and cowlings to grab all the air intake you want! :-P


And really, that's about all anyone can do at this point. Do it and prove it. (Nevermind the fact that it's been proven in the motorcycle industry. :roll: )

That's why I say we're flogging a dead horse here. What's the point of going on when neither side will be swayed?

[Hagar17]

As Tedium calculated the intake velocity at 15 psi is 450mph I think a little help for the intake isn't out of the question. Just like you say the engine and turbo is sucking air out of the intake. Ram just tries to help keep air in the intake. Not compress it.

Geez, 450mph that's close to the speed of sound!

Air pressure keeps air in the intake - it's about 15psi - if ram air just tries to help keep air in the intake and not compress it - it is doing nothing. :-P

[BDKR]

Ram just tries to help keep air in the intake. Not compress it.


And that my freind is the thing that the detractors are stumbling over. Either that, or they don't believe that it's possible to do so.


Geez, 450mph that's close to the speed of sound!


Depending on altitude of course. And we still need another 150mph at least. It's still bloody fast tho.

[BDKR]

Air pressure keeps air in the intake

Correct. Ambient pressure will keep air in the system. However, when you can look at a boost guage and note that it's reading 20 in at idle, then the intake is just a big vacuum cleaner hose. This means the ability of the engine to fill it's cylinders is only as good as the intakes ability to provide oxygen.

The exact same conditions apply upstream of the compressor inlet. Especially when you're generating boost.

So all we're talking about ever is making this portion of the system more effecient. Make sure that there is more air there and the engine has to do less work to breathe.

Therefore, if someone could build a system that at cruise speed could help the boost gauge reading at the plenum (or upstream of the compressor inlet) stay as close to 0 as possible, then they're improving the efficiency of the inlet tract.

Are you seriously telling me that this doesn't make sense?

[davidmacq]

No, they will keep hammering on how ram air doesn't make boost and isn't a turbo replacement. Very sad indeed. Let's not feed the trolls.

[Hagar17]

I think ram air or utilizing the high pressure point at the front of a vehicle maximizes efficeincy of the intake by reducing the negative effects of flow that the air filter may assert and prevents the negative effect of a low pressure point intake (like at the back of the vehicle) and also to ensure cold outside air is drawn into the engine as opposed to hot engine bay air but I do not think that it provides an extra benefits beyond that. Unless you compress or boost the air pressure going into the engine standard air pressure provides all the intake air needed.

[davidmacq]

Also we must remember the ambient air pressure will only try to keep one atmosphere of air in the intake. When the turbo is putting 2 atmospheres in the engine 15 psi, it will be sucking twice as much air through the intake. Ambient air pressure will never put that much air in the intake. Thus intake inefficiency.

[davidmacq]

Of course Hagar, noone is arguing for more effects than that. Yet, we keep getting pounded with arguements against it.

Compressing is the turbo's job.

One of the biggest benefits seems to be throttle response. Think about when you are cruising, but not making boost, then you floor it. The turbo is going to try to ramp up to max boost quickly, the sucking begins! Yet, at first the turbo doesn't have momentum? The difference between slight negative pressure non ram air and possible very slight positive pressure of ram air, or less negative pressure will help the turbo create boost faster?

Not sure, but there must be some explanation for the better throttle response.

[BDKR]

... and prevents the negative effect of a low pressure point intake (like at the back of the vehicle) ...


So now you're in agreement? :rofl: :rofl: It was hard to tell from the paragraph. Don't let Isaac see it.

[RYRY745]

nope im just saying when your making 13psi ram air is a moot point. Also with a four stroke engine when the intake valve closes i would think this action would stop ram air in its tracks. im also saying that it does have an application on a twostroke engine where exhaust scavaging & open intakes really make a difference in how it runs.

Yes i probably should put on the dunces cap for i have no engineering classes under my belt.

[davidmacq]

Intake valves are on the other side of the turbo from the ram air anyway.

Try making 13 psi on tiny volvo mitsu turbo. As you superheat the air more and more that little help from the ram air might just help the turbo relax a bit.

[Hagar17]

my heads hurts - I think I will lie down for a while -

go go rock'em sock'em air intake robots!

[BDKR]

go go rock'em sock'em air intake robots!


:rofl: :rofl: :rofl: :rofl:

Well, it's all good. I'm trying to be light hearted about the whole thing. As I said earlier, one of just needs to do it and find out.

[brucepick]

Boy, that dead horse sure is sore now from all that beating.

Anyway, once we've gotten past the "Ram is NOT turbo" thing, it seems pretty obvious that any improvement in availability of air to the intake would be a good thing.

Um, it's pretty similar to the age-old efforts to free up the exhust system with bigger pipes, freer-flowing mufflers, etc. Who would claim it's a bad idea to get the exhaust out of there with less resistance? If you can get the air in with less sucking effort on the part of the motor or turbo, that should be good.

For my daily (NA) driver, I'm still planning to duct air in via a fatter hose (or 2) than the current stock shorkel.

For a neat setup, change to dual (not quad) round headlights, and put intakes inboard of the headlight positions. There's just enough space between where the bulb would be and the radiator/condenser for an intake.

[RYRY745]

Intake valves are on the other side of the turbo from the ram air anyway. (duh!)

Try making 13 psi on tiny volvo mitsu turbo. As you superheat the air more and more that little help from the ram air might just help the turbo relax a bit.

My point with the intake valves was that they close. This closing action required for the powerstroke stops the intake charge from entering. With a two stroke this is not a problem. There is that little guy called a reedvalve. Kind of like a check valve.

Yes my little mitsu does make 13psi everyday. Maybe not @ upper end near the redline where it runs out of flow but it does @ 3000 rpm. How often does your engine stay @ 5000? Mine doesnt very often. It spends most of its time less than 4500 rpm. Yes its hot. It would probably take a liquid to air core with an ice pack on top of it in order to bring the temps down to something reasonable. You can even feel when the air is super heated... You can feel it running out of fuel with the green tops.

But anyways my point being ram air would have more of an effect on a twostroke application than on a 4stroke app.

[BDKR]

But anyways my point being ram air would have more of an effect on a twostroke application than on a 4stroke app.


Yes! Your point. But is your point proven? Practice at the highest level of motorcycle racing is not in your favor as they are using Ram Air systems on 4 stroke engines.

[mikep]

If it were a pump that compressed the air (pressurized it) this would be true - but the air will not compress that easily it will simply blow past and around the scoop. Again try and hold a balloon out your window with a big sccop in front of it and tell me how fast you need to go to fill it up. :-P
All I was doing was refuting this statement:
"I thought the engine will suck air in much faster than the speed of the air rushing by the vehicle"
Did I fail?


Boy, that dead horse sure is sore now from all that beating.

sure is.

[Neil Peart]

C'mon Neil! That only applies downstream of the turbo. I suspect you may be suprised at how in-effecient your inlet tract is upstream of the compressor.


oh sho nuff man. But you get the drift;-) . If you wanna talk about in-effecient, lets discuss the combustion engine itself :-P

[BDKR]

If you wanna talk about in-effecient, lets discuss the combustion engine itself :-P


Oh yeah... no doubt.

[Neil Peart]

Oh yeah... no doubt.

it would be killer to have at least a "mostly efficient combustion engine". Boost would be close to twice as better as it already is :-D .

But its not even close to that, thanks Adam and Eve.:roll: :-P

[RYRY745]

diesels rock, two strokes rock but bad emissions.... Four strokes suck squish bang blow...