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Old 03-29-2006, 08:02 PM   #76
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I understand the idea (inferior and Kenny) about where the heat goes, but my idea, and the other ideas, are mostly conjecture at this point. So don't side with me yet.
Cool discussion.
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Old 03-29-2006, 08:37 PM   #77
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hmm...i'm not sure how i feel about the slower warm-up versus efficiency thing. i dont think it's as cut and dry as less heat = less efficient.

if the burn is faster, then i wouldn't think it would transfer as much heat to the head and piston. but it's thermodynamics, all i know for a fact is that you can't win, and you can't break even.
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Old 03-29-2006, 09:00 PM   #78
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Quote:
Originally Posted by 740Weapon
so...

diesels are efficent because of their high compression and that they USE That high compression... diesels have no throttle plates.

the throttling process of a gasoline engine makes the effective compression pretty darn weak under most driving conditions.
Not quite correct. Diesels are effiecient because they are a lean burn engine - very little fuel goes out a well running diesels tailpipe. If gas engines ran at the same a/f ratios you'd have knock knock bang!

Quote:
Originally Posted by acbarnet
in terms of fuel efficiency, turbines are at the far opposite side of diesels, they make alot of power for their weight but you pay dearly in fuel consumption...
Also not correct - a recirculating turbine is by far the most efficient petrol based engine out there but they lack operating range meaning all the work is done at 90 to 100% and in some cases 98% to 100% Throttle and turbine speed.

End threadjack

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Old 03-29-2006, 09:11 PM   #79
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Quote:
Originally Posted by Renny_D
Not quite correct. Diesels are effiecient because they are a lean burn engine - very little fuel goes out a well running diesels tailpipe. If gas engines ran at the same a/f ratios you'd have knock knock bang!

Renny
diesels only "lean burn" at idle/cruize.

and operate by compression ignition. i.e. there isnt a "flame front" so to say. any fuel injected around TDC on a diesel spontaneously ignites.

under WOT diesels go to the same type of a/f ratios as anything else.

gasoline engines will not ignite a fuel mixture at a diesel's idling a/f ratio.

the "lean burn" efficiency gain is because compression ratio up=efficiency up. and no throttle plates mean very high compression at all times.

gasoline engines do not "waste" fuel in the tail pipe.

Fun Fact: in thermodynamics the gasoline cycle is more efficient then the diesel cycle.

its the diesel's higher compression ratios and real world operating conditions that make them so efficient.
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Old 03-29-2006, 11:36 PM   #80
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740weapon is totally right... I was just reading an engine design book and noted the same things. otto cycle (four stroke spark ignition) engines are more efficient than diesels when unthrottled... but in actual use they have to be throttled which reduces their efficiency (especially for cruising). they are also limited by knock so need to run lower compression ratio's than optimal. the lean combustion of diesel's actually hampers their efficiency. if you've seen a graph of fuel efficiency vs A/F ratio you'll see that the most efficient combustion occurs at a specific point, and this applies to diesel's as well.

also acbarnet is right about turbines. they are used in planes because they are very light for their power output. in terms of efficiency otto cycle and diesel engines are better. combined cycle steam/gas turbines can be more efficient, but these are significantly more complex, mostly used in power plants. you can do combined cycle piston engine/steam as well... although i've never heard of this being done in a production engine.(bmw has a system in development that sounds cool if you want to google it)

as for these grooves... lets see some hard data...

james
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Old 03-29-2006, 11:54 PM   #81
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if you want to see a REALLY efficient engine, look up the napier nomad. It was a hybrid diesel-turbine engine that achieved almost 50% efficiency.

basicaly it used an axial-flow turbine as a turbocharger and used the exhaust gas from it to drive a free power turbine, so it got as much power from the combustion as possible, it was a VERY cool engine indeed.

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Old 03-30-2006, 12:05 AM   #82
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while we drift off topic, another cool engine: http://en.wikipedia.org/wiki/Wartsila-Sulzer_RTA96-C

biggest diesel in the world... 50% thermal efficiency.

james
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Old 03-30-2006, 10:58 AM   #83
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The stat thats in the grooved head is a 92, the one i'm used to in the 531 is 88, if that's why the engine takes longer to warm up i apologise, i can only get 88 stats from my local parts place so i ASSumed that's all there was.

i have emailed 3 board members with the deck thickness pics, if 1 of you could put them up i'd be grateful.

As far as hard evidence goes, this mod will cost you a headgasket and a cam cover gasket, i haven't got the money or the inclination for dyno's etc, i'm trying to be as analytical as i can but there is a limit to what i can prove to myself or others and most of what's claimed for this would only be believed by people doing this mod themselves, already people have gone well my car dosen't ping at those settings, the chances of an american spec +t or turbo engine having the same afr and static c/r as a european e engine fitted with a carb are none existant, but surely it's better to test this on an engine thats prone to knock if pushed, my fb is nowhere near as prone to knock as the e by virtue of it's lower c/r, i know the causes of knock and have tried my best to induce it, highish c/r, stupid advance on the timing, lean mixture, if anyone can think of any other ways i can test this i'm interested. Les.
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Old 03-30-2006, 11:13 AM   #84
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there wasnt a pic attached, re-send the email.
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Old 03-30-2006, 04:54 PM   #85
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pics:






any chance you might cut it across the runners?
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Old 03-31-2006, 05:19 AM   #86
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i do like how you went straight through an exhaust stud and glanced one of the valve seats.
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Old 03-31-2006, 08:18 AM   #87
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I just stood and watched, my mate and this guy he does some cassy for now and then did the deed, where do you want the cut they said, straight between the valves says i, good job he said there was no way i was going to cut through the valves with this saw, so there you have it, seems like theres plenty of meat.

By the runners do you mean cut down the centre of each valve? tell me where and i can get it cut, probably be middle/ late next week though.
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Old 03-31-2006, 11:30 AM   #88
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Well if that one was not a boat anchor before it certainly is now.
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Old 03-31-2006, 12:42 PM   #89
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Very off topic, but: I am going to name my next band Somender singhs groove theory.
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Old 03-31-2006, 01:57 PM   #90
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The waterholes had corroded that bad there was nothing left to seal with.

Yeah ssgt just rolls of the tongue lol.
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Old 05-04-2006, 01:01 PM   #91
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Quote:
Originally Posted by linuxman51
here are the pics.
mikep is right as always, but its interesting to consider the dynamics involved, what i'm picturing in my head stock vs cut would seem to indicate benefits from having the cuts. Wonder if more but smaller cuts would do better?

Hi Les, & gang

Why cut the groves where you did?
It is not best cutting the grooves on opposite sides?

Or is the idea to cut the longest groove you can to reach the area of the piston / wall which isnt as exposed to the spark /flame when on the head (if you know what i mean).

any more observations?? - as this is very interesting.
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Old 05-04-2006, 01:17 PM   #92
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i agree, quite interesting, what does the head gasket look like? i wonder if it is damaged in any way at points in line with the grooves any more than elsewhere, since i would expect a sort-of jet of hot air from the groove as the piston moves away from the combustion chamber?
i'll be changing my head gasket next week (coolant has been "disappearing"), maybe i'll notch the chambers while i'm at it.
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Old 05-04-2006, 05:09 PM   #93
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The groove opposite the spark plug is supposed to be obligatory so that a "jet" of air fuel mixture is aimed at the ignition point, the second smaller groove was my placing, after giving this some more thought over the 6 weeks it's been done, i'll be doing a mk2 version on the same head in a couple of weeks involving circulating the flame front, if it works great, if not i'm already more than happy with the mk1 results, better detonation resistance and a smoother more tractable drive are proven to my satisfaction, i couldn't attempt any mpg figures because of a blowing exhaust and buttometer power levels would be meaningless and to be honest i wouldn't expect any increase in power, if better detonation resistance means i can run 2-3-4 psi more safely and i can also do 30mph in 5th in traffic then it's a worthwhile mod considering all it costs is a headgasket.
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Old 05-06-2006, 05:01 PM   #94
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Quote:
Originally Posted by linuxman51
here are the pics.
mikep is right as always, but its interesting to consider the dynamics involved, what i'm picturing in my head stock vs cut would seem to indicate benefits from having the cuts. Wonder if more but smaller cuts would do better?


I think you groove placement has merit. I see it this way, the squish area will generate mixture movement, and the grooves concentrate this movement and direct it to the location you choose.

Another thing to consider when choosing groove location is in cylinder temperatures and moving cold mixture to hot areas of the chamber.

Here's a picture of my first two groove effort. I have a totally different three groove layout in the works, will post pictures later.


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Old 05-06-2006, 05:17 PM   #95
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Nice Tull reference.

Nice work on that small chev head, too.
Whose casting is it? It's a "heavy" style, like an early head, but with a nicer chamber.
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Old 05-06-2006, 06:09 PM   #96
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Quote:
Originally Posted by mikep
Nice Tull reference.

Nice work on that small chev head, too.
Whose casting is it? It's a "heavy" style, like an early head, but with a nicer chamber.
He feels the piston scraping --
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No way to slow down.

Tull, showing my age.

Pro Topline, recently bought out by RHS. It's a spin off of the LT1 head from the mid to late 90's. This one has the big valves and huge ports. Here's the piston burn pattern with a single groove from last year.

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Old 05-06-2006, 06:49 PM   #97
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Quote:
Originally Posted by automotivebreath
Here's the piston burn pattern with a single groove from last year.

That's amazing! This pic alone should be justification for doing the mod.

So anyway, aren't you also over on the mpgresearch board?

Cheers,
BDKR
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Old 05-06-2006, 08:18 PM   #98
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Quote:
Originally Posted by BDKR
That's amazing! This pic alone should be justification for doing the mod.

So anyway, aren't you also over on the mpgresearch board?

Cheers,
BDKR
I am paying close attention to the mods done by MPGMike and others at mpgresearch. Diamond Larry is installing his modified head this weekend; can't wait to see the results on his drive home. My prediction stands at 56.83 MPG with a good tail wind. Of course I love to be proven wrong.

As for the burn pattern, I'm attempting to get rid of the wash in the upper left.
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Old 05-07-2006, 04:32 AM   #99
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Hi Automotivebreath, i'm thinking of another main groove to the right of the centre one, so after the stream has hit the plug area it is pushed to the left, and where it hits the high wall a couple of short deep grooves to allow the flame access to the squish area, i hope that is understandable, thanks for the visit, it was your work that proved there was something in this strange idea, i just wish another of the volvo guys would try it, it gets a bit tiring being considered a nutter and bullcrapper by most on the board, we would have 2 nutters then lol.

Many thanks to you, somender and mpgmike, Les.
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Old 05-07-2006, 01:12 PM   #100
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Quote:
Originally Posted by Les, slight limp
...i'm thinking of another main groove to the right of the centre one, so after the stream has hit the plug area it is pushed to the left, and where it hits the high wall a couple of short deep grooves to allow the flame access to the squish area....
I think I understand; a drawing would be good. My advice with groove cutting is to take it slow; too many grooves will slow the squish velocity, not good.

I see benefit in the second groove in the large squish area opposite the plug.

How wide are the initial grooves?
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