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Old 03-11-2012, 02:54 PM   #26
John2x240
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I think that you should move the air dam further forward or you may get a pocket of air under the nose which could raise the front of the car. Maybe you should have something like this:

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Old 03-12-2012, 07:41 PM   #27
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It's going to be better than it was, for sure. The air should be directed around the car now and anything that was already going under the car before is now reduced.
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Old 03-12-2012, 10:29 PM   #28
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Looking at your front end, I don't see much of the airflow going out to the sides. What I see is most of the air going down to the ground, and then the only place it has to go is under the car. I see you have some holes and a lower air entry. If you duct the outer holes to the front brakes and cut out the ribs on the lower air entry and duct it to the radiator/oil cooler (if you have one) that will reduce the air pressure at the front, and if you add a lip to the bottom of the air dam (about 3/4" [+/-]), you may then get some of the air flow to exit at the sides, but I still think that an air dam like the one in the photo in my post would be a better choice.
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Old 03-13-2012, 03:19 PM   #29
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This is just the start of seeing what will work the best. I plan on trying to let as little air into the engine compartment as possible, just as much that is needed cool the engine. That said the lower grill will be blocked off and possibly some of the upper grill. Or maybe it would be better to block off more of the upper grill and leave the lower one open (the lower grill directs air to the radiator). Thoughts on that idea? There will be a small splitter on it to help get the air out the sides. One of my ideas was to put a big air dam that basically runs from the lower part of the grill down to about 6" off the ground and run a tray/splitter back to the front X member. But I am thinking that the frontal area would be way to big and might actually slow the car down more than anything. Thoughts on this? I still would like to try it at some point regardless.

Marc
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Old 03-13-2012, 06:31 PM   #30
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Quote:
Originally Posted by John2x240 View Post
Looking at your front end, I don't see much of the airflow going out to the sides. What I see is most of the air going down to the ground, and then the only place it has to go is under the car. I see you have some holes and a lower air entry. If you duct the outer holes to the front brakes and cut out the ribs on the lower air entry and duct it to the radiator/oil cooler (if you have one) that will reduce the air pressure at the front, and if you add a lip to the bottom of the air dam (about 3/4" [+/-]), you may then get some of the air flow to exit at the sides, but I still think that an air dam like the one in the photo in my post would be a better choice.
Looking at the front end before, you'll see that even more air was going underneath the car and hitting the front tires/filling up the wheel wells. Now there is more frontal area, but that air dam underneath has a slight V profile to it and pushes air around the front wheels in addition to not just being an open space. We added deflectors above the extended part of the dam(~3" out on either side of the body) to further support it and direct flow around the wheel wells. We plan to eventually add a splitter underneath the air dam to help trap the air there and encourage it to go around the car - as well as pull the front of the car down a bit at speed.

The holes for the factory bumper setup do have brake ducts riveted into their openings. The center, slotted area(which was blocked off completely on earlier cars) we have run blocked off, but as Marc mentions above, it may be a better idea to grab air from that high pressure area to stuff into the engine bay instead of air at the top of the grill opening. Marc has gotten a little crazy with little ducting plates behind the grill/headlights and foam stuffing in all the cracks around the grill/surrounds.

Then we have to figure out what we want to do for the rear of the car... A lip spoiler of some sort(even if it's just for fun!), and then we are likely going to do SOMETHING at the trailing edge of the roof. Maybe some spoiler that directs air down the rear windshield and straight back, or just down, or just straight back orrrrrrr some diffusers ala recent Mitsubishi EVOs...?

This, of course, excludes doing the more necessary work:
- Re-securing the seat back now that we lowered it and it's at a greater angle now
- Driving the car and seeing how the brakes work. Likely re-bleeding them with some higher temp race fluid
- Re-installing the brake ducting for the front and rear brakes
- Seeing how bad the transmission is(shot synchro?) and installing a 5th gear lockout plate
- Getting an extender for the steering wheel adapter or extending the steering shaft for better seating position

Among other misc. things.

Last edited by klr142; 03-13-2012 at 06:42 PM..
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Old 03-17-2012, 03:04 PM   #31
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First gen RX7s have front end roll under that's even worse than a 142. Here are a couple of air dams for them which eliminate the air pocket which are similar to what I'm suggesting for your car:

This one is from a Mazdaspeed member



This is my car



Both have a fairly large cold air intake for the radiator and oil cooler, which is really needed as racing temperatures for these can be really high. Also, you'll note that the outer ends on my air dam are shaped to collect the air that isn't taken in for the rad and cooler and direct it to the sides. I think an air dam design similar to mine would work quite well on your 140.
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Old 03-17-2012, 03:08 PM   #32
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The problem is, you don't have anything but a bumper above your air dam, where as we still have a massive flat nose with a large grill opening. We don't need any more cooling airflow than we already have, we actually want to block off some of it. If we block off some of it and then add a 1 foot tall WALL underneath the front grill, it's going to be blocking a TON of air and slow the car down. That is a TON of added frontal area with no where for the air to go. The "design" we have now allows some air to be pushed down and around the grill/headlights and then get caught by a not yet built splitter and forced around the car. There is a slight taper to the spoiler on there now that helps direct air around the car.

Speaking of this car, I need to go work on it... But I also need to get a car registered first, and it's looking like that isn't going to happen due to timing and other complications.
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Old 03-17-2012, 03:38 PM   #33
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Old 03-17-2012, 03:57 PM   #34
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Harold you have something to add? So Kyle if your not registering the car get over here.

Marc
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Old 03-17-2012, 04:01 PM   #35
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Nope, I just wanted to subscribe to the thread and show support. I'll help you guys out in October when I'm done with school and not getting my pile of **** 940 setup.

How's the thing coming along?
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Old 03-18-2012, 02:46 PM   #36
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It's coming!

https://www.facebook.com/pages/Gener...38575516219662

We need to bed in the brakes, finish up the actual splitter(cardboard one is just about done), do some higher rpm/race shifting to see how the transmission holds up(Marc, we should top up the fluid after last night!), swap out the rear springs for something stiffer(we removed the rear bar), add an extension to the exhaust, check the rear brake pad thickness, finish the seat support brace...
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Old 03-18-2012, 02:56 PM   #37
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Quote:
Originally Posted by klr142 View Post
The problem is, you don't have anything but a bumper above your air dam, where as we still have a massive flat nose with a large grill opening. We don't need any more cooling airflow than we already have, we actually want to block off some of it. If we block off some of it and then add a 1 foot tall WALL underneath the front grill, it's going to be blocking a TON of air and slow the car down. That is a TON of added frontal area with no where for the air to go. The "design" we have now allows some air to be pushed down and around the grill/headlights and then get caught by a not yet built splitter and forced around the car. There is a slight taper to the spoiler on there now that helps direct air around the car.

Speaking of this car, I need to go work on it... But I also need to get a car registered first, and it's looking like that isn't going to happen due to timing and other complications.
I realize the issues on your 140 are a bit different than my RX7. Actually, looking at the front of your car takes me back to the mid '60s when race car builders started to seriously look at aerodynamics, and when they started to experiment with what were then called "chin whiskers." As using wind tunnels was generally beyond the budget and availability of most of us, some devised what you could call "the poor man's wind tunnel," which consisted of setting up a good sized fan about ten feet in front of the car, and with the fan running at high speed, adding a smoke source, and then seeing where the air flow went. Some used 8/16mm movie cameras to record and study the air flow, but in those days it was difficult to get slow motion movies. Today, with videos that can be slowed down, you may want to try the poor man's wind tunnel, and see what you get with various air dam configurations.
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Old 03-18-2012, 05:47 PM   #38
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Not a bad idea. Could probably do the old trick of putting some yarn on the car and get somewhat of a idea of what the air is doing too.
Marc
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Old 03-18-2012, 10:02 PM   #39
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There's also the old oil spot trick, but it's a bit messy.
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Old 03-19-2012, 11:52 PM   #40
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This is kind of cool. apparently there's a guy running around town taking pictures of cool cars. Ive been peeped.
http://www.thestreetpeep.com/search/...&by-date=false
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Old 03-20-2012, 12:47 AM   #41
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Got closer to finishing up on a couple of things tonight.
Finishing up on the front air dam and splitter. Right now the splitter is made out of 1/4 inch plywood. I think I make one out of 3/8 as the 1/4 is not quite as rigid as I would like. I would like to think that it cant be any worse that it was and would like to think that it is better.


I was just messing around and made this to help clean up the front end a little. I'd like to think it cant hurt. I was going to make one for the other side but forgot the air intake is on that side and should let as much cool air in there as possible.

Still need to try to get the exhaust all the way out the back and a number of little thing. More to come soon.
Marc
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Old 03-20-2012, 12:13 PM   #42
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w00w00. We could slap some seam sealer or caulking in that split between the core support and fender, too. Then maybe fill up the area between the spoiler and the core support.
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Old 03-20-2012, 09:43 PM   #43
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Probably not that critical right now, but yeah, sealing it up is a good idea. As for stiffening the splitter, a couple of plywood ribs would stiffen it up for now, but round off the front and edges of the ribs. The splitter and air dam is gonna give you a lot more front downforce, so you may have to play with the suspension a bit if it makes the rear end too loose.
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Old 03-20-2012, 09:47 PM   #44
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We did actually take off the rear swaybar for other reasons, but will also be adding a rear spoiler and maybe something near the top of the rear window to direct airflow over the back of the car OR down the back windshield to direct air over the spoiler.

We shall see in a couple weeks!
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Old 03-20-2012, 09:54 PM   #45
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If I ever get the time and money to get my RX7 on track, I'm gonna look at vortex generators. Here's a link to site discussing them, and in the first post there's a link to a supplier. Oops, senior moment ... here's the link: http://corner-carvers.com/forums/showthread.php?t=37421
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Old 03-20-2012, 10:29 PM   #46
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We have thought about that possibility, thanks for the link(s)!
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Old 03-20-2012, 11:05 PM   #47
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Got the exhaust fabbed tonight. Kind of hard to see but goes under the rear axle and out the back. Should not be as mush noise or fumes in the car. Not that there was a lot to start with just that after 2hrs on track you could start to smell it a little. I'll pull it off tomorrow and get it all welded up.

I think at some point I would like to replace the hole exhaust. Its just kind of a hodge podge of quick fixes that could be much cleaner and tucked up closer to underside of the car. Oh well maybe some day.
Think I'll go buy 110 gallons of full tomorrow.
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Old 03-20-2012, 11:12 PM   #48
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w00h00! The exhaust isn't that bad... We don't really have clearance issues, do we? It can't go up higher, we already added clearance to the body! It's fine!

I have no complaints except we should add another hanger to the extension we just added to relieve some of the stress from the only other mount on there And maybe swap out that Flow[blocker]master for a straight through muffler at some point.

SEAT BACK SUPPORT!
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Old 03-21-2012, 07:59 PM   #49
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Quote:
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Got closer to finishing up on a couple of things tonight.
Finishing up on the front air dam and splitter. Right now the splitter is made out of 1/4 inch plywood. I think I make one out of 3/8 as the 1/4 is not quite as rigid as I would like. I would like to think that it cant be any worse that it was and would like to think that it is better.
I like this car a lot!

A rough rule of thumb i've been given for splitters is that they (and their mountings) should be strong enough to stand on. This obviously depends on your own personal bulk, but I'd say strong enough to take at least 100kg. Aerodynamic forces can be very high.
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Old 03-21-2012, 10:43 PM   #50
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I think that you may be correct for cars that regularly get over 250 kliks on a longish straight, but I don't think that their car will be reaching those speeds. If the mounts are sturdy and they add a couple of stiffening ribs they should be OK.
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