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aerodynamic improvements

Old 07-27-02, 05:47 PM
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aerodynamic improvements

I'm looking for ideas for a 3rd gen to improve the downforce on the car. I noticed a large improvement in high speed stability when I added the R1 lip, but now I'm going to take it to the next level. So any ideas for front splitters and reinforcements to the splitter so that it actually applies force to the chassis? Also any ideas for rear wings? I've been looking for Aluminum of carbon aerofoils that could be used to build a wing, however I havn't been successfull in finding any.

Matt
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Old 07-27-02, 10:45 PM
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i use a mazdaspeed gtc wing, which is adjustable somewhat. it has a low, med, and high incident angle adjustment. i've notice a significant amount of downforce at 80mph and above. i notice this in that at my recent track event, i had to dial down the the downforce to prevent scary understeer in the higher speed corners. this was a temporary bandaid to a tire problem, but nonetheless demonstrated to me that the wing was functioning quite well.

good luck
fabian
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Old 07-28-02, 01:57 AM
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I am surprised that no one has made some sort of aero foil that can be bolt on under the hatch that sticks up upward when the hatch is closed. Kind of a nascar spoiler/foil except it is mounted under the hatch and sticks out when the hatch is closed.
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Old 07-28-02, 06:21 AM
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How about this...

When you run on-track, you must have your windows rolled down. (Unless you're drag racing which is just the opposite... but that's another topic) This tends to create a high pressure area in the hatch area, as anybody who's had the rear carpet come forward and smack them in the back of the head while tooling along the backstretch can tell you.

Why not make a spacer so that the rear hatch stays open a few inches, allowing this high pressure to bleed out over the rear deck, negating some/all of the natural low pressure area at the back of the car that creates lift.

Just a thought...

- PJ (And has anyone else noticed greater high-speed stability with the sunroof popped up?)
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Old 07-28-02, 09:27 PM
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my buddy on his FB notices a lot more stability when we are racing when his hatch is popped up a little bit
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Old 07-29-02, 03:03 PM
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Big *** warrior wing
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Old 07-31-02, 05:40 PM
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My neighbor who used to race C4 Vettes used a metal prop/bracket that opened the rear hatch about 1". The hatch would lock into place with a clip to secure the lid (rear hatch), and then a metal bar to the lower body attachment point. Basically an adapter to create a 1" gap.

GNX7
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Old 07-31-02, 08:55 PM
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RE rear diffuser.
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Old 07-31-02, 09:57 PM
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Originally posted by djantlive
I am surprised that no one has made some sort of aero foil that can be bolt on under the hatch that sticks up upward when the hatch is closed. Kind of a nascar spoiler/foil except it is mounted under the hatch and sticks out when the hatch is closed.
FEED makes a splitter for the front and rear, but its A LOT of $$$....and not worth it. Unless your going over 100mph all the time, a rear spoiler isn't going to do much for you. I'd spend your money elsewhere, IMO....
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Old 08-01-02, 06:02 AM
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on a FC, dunno about a FB or FD haven't taken much notice, just open the hatch and put a couple of solid rods from the hatch onto the boot floor, you'll get some MEAN downforce with that huge **** thing deflecting air upwards, but be careful cause it'll suck back alot of exhuast gases. bawahahaa
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Old 08-01-02, 11:48 AM
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You'll find that the in-hatch area has a much higher pressure than the above-deck area. The high pressure air from inside the car rolls out over the deck and reduces the low-pressure area over the deck, reducing downforce, as well as the fact that the open hatch reduces windspeed over the rear thus reducing the low pressure area in the first place. (probably why you notice the air sometimes flowing "backwards" INTO the cabin)
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Old 08-05-02, 03:12 PM
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I'm not an aerodynamic engineer, but based on looking at the current ALMS and Grand-Am cars (as well as places like www.mulsannescorner.com ), the place to focus is underneath the car. The object being to keep as much air as possible from getting under the car, and aggressively evacuating there air that does get beneath it.
.02 cents.
Steve C.
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Old 08-09-02, 08:42 AM
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peejay,

why do you have carpet in your racecar??

Justin
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Old 08-09-02, 10:20 AM
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That was the last time
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Old 08-11-02, 12:49 PM
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I'm going to try to get my shop to fab something to keep the hatch open a bit. And, it'll give me an excuse to here my exhaust on the open road!
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Old 08-16-02, 01:15 PM
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I opened my hatch a little while lapping and got black flagged... I don't think you're allowed to do that in some places...
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Old 08-17-02, 01:59 AM
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Maybe they are scared interior pieces will fly out onto the track?
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Old 08-20-02, 01:36 AM
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You'll find that the in-hatch area has a much higher pressure than the above-deck area

Hmm, on an FC there is definetely ALOT more downforce on the rear hatch then inside the cabin. I have tried driving w/ the hatch open and it slams shut once you get up to around 40mph- even w/ the side windows down. If you look at "the FC diagram" you can see there is a high pressure area at the rear lip of the hatch right where it transitions to the flat rear deck. Interestingly there is even a concave area in the glass there- I don't know if that is just a by product of the molding system or if Mazda actually tailored that area for aerodynamics.
Mazda did certainly use the wind tunnel a bunch on the FC. .30 Cd is still awsome 16 years later! I would not doubt the FC is actually aerodynamically better than the FD. Does anyone know how they really compare?
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Old 08-21-02, 11:19 AM
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the hatch area is not as high pressured as one would believe. carpet is easy to lift. i popped my hatch and left it stuck to the seals on my sa (damn thing never pops up anyway) and drove around the expressway at 80+. it never vented or broke the seal. now anyone who opens these knows that they don't require a large amount of force to open, so the pressure isn't causing more then maybe less then 10 lbs of lift. i know a guy in nashville had a custom aluminum front lip that had the small adjustment rods on it so that he could adjust the angle of attack. i also agree with qwck10th on making a front and rear diffuser. the front is pretty sinple and can be made from 1/8" plastic sheets utilizing mounting points that already exist under the car. th rear is a little harder as in you want to avoid the exhaust. this will smooth airflow out underneath the car reducing drag.
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Old 08-21-02, 12:48 PM
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Originally posted by BLUE TII
Mazda did certainly use the wind tunnel a bunch on the FC. .30 Cd is still awsome 16 years later! I would not doubt the FC is actually aerodynamically better than the FD. Does anyone know how they really compare?
The numbers I've seen are .31 for a 89 GTUS and .29 for an FD...I'd imagine that's a "wingless" FD though.
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Old 08-30-02, 12:42 AM
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Interesting. Everything I have read said standard FC had a .31 and the sport aero package dropped it to .29 (lower lip extended infront of tires, spats behind the front wheels, in front of the rear wheels and a very low flat spoiler).
FD does appear to be wider- so it has more frontal area aerodynamics has to make up for?
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Old 09-03-02, 12:52 PM
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BLUE TII:
The FD may be slightly wider at the rear (vs fc) but has a MUCH lower roof line and looks to be less frontal area.
Fluxen:
The FD .29 cd is indeed for a CLEAN (no wing/spoiler) fd the R-1 front lip adds hardly any drag but offer a significant improvement in front downforce. The stock 93-5 rear wing is a disaster, lots of drag (cd to .32) and little or no downforce.
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Old 09-16-02, 02:10 PM
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So, what is a good aftermarket rear end wing that doesn't increase drag (much) but does add downforce.

I just don't like the FD's without the rear spoiler and I don't want a giant Dragster style wing on their either.

Note, I'll probably only road race once or twice a year. Looks are more important to me. Also, cost. I'm basically happy with the Stock touring looks, but I'll be repainting this winter (hopefully) and thought it was a good time to ask.

Thank in advance!
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Old 09-18-02, 04:35 PM
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Originally posted by peejay
How about this...

When you run on-track, you must have your windows rolled down. (Unless you're drag racing which is just the opposite... but that's another topic) This tends to create a high pressure area in the hatch area, as anybody who's had the rear carpet come forward and smack them in the back of the head while tooling along the backstretch can tell you.

Why not make a spacer so that the rear hatch stays open a few inches, allowing this high pressure to bleed out over the rear deck, negating some/all of the natural low pressure area at the back of the car that creates lift.
Sounds like a great way to get airborne. If you open the hatch a bit, you will end up with low pressure on top of the hatch, and high-pressure air flowing under the hatch = airplane wing.

Originally posted by peejay
(And has anyone else noticed greater high-speed stability with the sunroof popped up?)
I don't think that an open sunroof is allowed in any type of high-speed racing. In fact, it needs to be bolted shut for SCCA track events.
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Old 09-18-02, 05:48 PM
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At Nelson Ledges FunDayz last Friday, they had me close the sunroof.
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