Woz

My car was recently wrecked by my dad, long story, but we bought it back as salvage after the insurance company totaled it. I am rebuilding it as a track car.

I tried searching but didn't find anything useful. Does anyone know about what front and rear body parts are good for downforce, are there any good diffusers that can help with this?

I was thinking to go with the MazdaSpeed front and rear but looking at the rear the diffuser looks kind of small and the front doesn't have anything. Before I delve into spending a lot of money I was looking for some insight to this.

TopGear8

iTrader: (3)

I'm not sure about downforce...But the MazdaSpeed bumper has bigger inlets for better cooling...

kersh4w

iTrader: (3)

the mazdaspeed kit was designed using a wind tunnel.

it is very aerodynamic. consider this, the multiple race winning rolex series speedsource rx8 #70 gt car uses the mazdaspeed kit. they use a bigger wing of course.

altiain

iTrader: (3)

They also use a tubeframe and a 3-rotor engine, but who's counting?

kersh4w

iTrader: (3)

right. all that says is that they are using good products. i still dont see any discrepancy.

PBlue

iTrader: (1)

he didnt ask about the engine, he asked about the kit...
obviously 2rotor < 3 rotor < 4 rotor < 5 rotor ... etc

Id love a bike with a single rotor... fun stuff.

RK

iTrader: (1)

FWIW SpeedSource only uses the big wings on their GT cars. Their Koni car uses the MS wing.



And you should never get a fiberglass replica kit regardless of application but if you're tracking the car make sure you use the real thing. You may be able to get it through the competition program as well. Warranty is voided but I believe they will give you body parts cheaper as long as you track the car for competition in a certain time period.

racewithroar

Guys,

The Mazdaspeed kits are mandated by Grand-Am. It's either MazdaSpeed or stock.

As far as aerodynamics, I don't really have a whole lot of experience with the cars without the kits so I can't comment.

I will echo the earlier comment that the MS front bumper is crucial for cooling. And if you get the front bumper - the car just looks funny without at least the side skirts and spoiler/wing combo.


Adam

thecow135

get the rear too!

Woz

So the speedsource team has to use MazdaSpeed? If I am correct with that statement it doesn't necessarily make it the best thing to use, I am not going to be doing any huge competition racing any time soon, if ever. I dont want to get the MazdaSpeed body, just because SpeedSource has to use it, It doesn't appear that they use a front, or in the case of the 69 car, rear diffuser.

No one knows if there has been any testing done somewhere between body kits or any insight on what key elements would be to look for that would help with increasing downforce?

Jedi54

iTrader: (7)

mazdaspeed has bigger openings in the front for air. If anything, that right there could help at the track.

SouthFL

Traditionally, a front splitter and a rear wing.

racewithroar

Well, again, Grand-Am tightly controls the aerodynamics of the cars that race in the series. I should have been more specific in my first post.

In ST - The MazdaSpeed rear diffuser is not legal - only the Front Bumper, Side Skirts, and Spoiler/Wing combo are legal. And the wing is quite adjustable - you can get a pretty big angle on the thing if you really wanted to.

In GT - They must keep the car looking pretty close to the real thing. The rules allow widening of the fenders by 2 inches on each side to accomodate the tires, and they allow the front splitter and an under spoiler in the rear. The wing is a specific model made by Crawford that is mandated.

I wouldn't discount the MS kit just because we have to use it. I am sure that it is better, I personally just don't know how much better than stock. However, our better drivers can discern differences between the cars with and without the wings. Each one likes having the wing. And again, aerodynamics shouldn't be your only concern.


Really one of the best aerodynamic things you can do is just lowering the car. The less air going under the car the better. For both classes, the minimum ride height is 3 1/2." That is, they run a bar under the car that is 3 1/2" high, and if it rubs on anything, not just the body work, the car fails. That ride height is easily attainable with just about any lowering coilovers. (But know that it can become difficult to load the cars on and off certain types of trailers when they are sitting that low - we often need to take the front bumper off to get the cars on and off our single car trailer. You can also run into suspension geometry issues by getting the car too low)

Also front splitters become more effective the lower you get the car.

Other things to think about include a louvred hood and a complete flat undertray with rear diffuser. Even blocking off the air inlets for the radiator and oil coolers will help - but if you do that, expect to be running way too hot than is comfortable for the rotary motor.

-- Adam

alnielsen

iTrader: (4)

Just to add to what Adam said, the air under the car is very turbulent and builds up. Not only does this cause drag, but at high speeds it actually raises the car. The early Audi TT's were having accidents on the autobahn because of this. The rear was loosing traction, causing the cars to spin out (Audi has since made corrections). This is why cars are lowered and have air dams. It's for more than just looks.

eviltwinkie

Woz...I'll translate...

Function before form dude...

Use tried in true and dont mess with it...you'll have a ton of other things to be thinking about...

Razz1

RE-Amemya is a good kit

Try Japan parts to get it

Woz

Which is why I made my original post.....I have never said anything about the look of the kit, I just asked what kits provide good down force.


Why is the Mazda Speed kit better than the "X" Kit, ok, it has better cooling than stock, what about down force


Why.

eviltwinkie

why are you so concerned about downforce? I seriously doubt you require it...

SouthFL

1 day's instruction at a track day with a professional driving coach will cost you less than an aero kit. What you learn will make you go faster than the wing and air dam.

Woz

I have done 4 Drivers Educational events with The Drivers Edge, I have done 3 track days run by the Track itself and 3 solo track days by myself at MSR-Houston.


I am sorry for trying to find out information on the forums, please forgive me for my grievous error.

racewithroar

Woz,

I've done some research for Wind Tunnel test results of RX-8 kits and can't find any. I know the MazdaSpeed kit was wind tunnel tested but I don't know th exact results. As for any other kit, I don't know. My guess is that most other after-market kits are not tested scientifically, but there may be some around. Wind tunnel testing costs $$$ so if you are going to do more research I would say to pay more attention to the more expensive kits.

Adam

eviltwinkie

Heh...dont hate teh playa hate teh game yo!

For the most part...I'm willing to bet 90% of all commercially available kits are NOT tested past..."this looks faster"...Remember that most of those companies are in the market to sell products that appeal to a market. The margins are slim and testing every product would be financial suicide..

The MS parts are made by people who are generally going to have the resources to do the testing in order to slap a name to the brand. Function before form...the only body kit which we know work well, durable, aid in cooling, and have been tested for track use...is the same kit most teams are using.

Downforce follows a law of diminishing returns...the more you use, the less you get somewhere else...Due to the nature of the car, it simply does not require as much downforce as you might be thinking it does...which again comes back to...why the interest in downforce?

If your not getting grip coming out of a corner, or the nose feels like its slipping or pushing, it might be your setup...If you are coming from an AWD background, you might simply have learned car control the wrong way and are misapplying the car...

What I'm really asking is...I'm trying to address the root question...which is...Why the concern about downforce? Maybe there is something you are looking for and we can answer it directly.

BTW...if you get a chance run w/ PCA...TDE is good, but PCA seems alot more organized...

SouthFL

I don't mean track day instruction- I mean, hiring someone like an active/ semi active Grand Am/ ALMS/ WC driver who will shave more seconds off your lap than anything you can bolt on to your car.

Granted, given that your car is totalled and needs body work anyway, what you're doing is a valid excercise, as you car needs body cladding.

Remember though, assuming you've mastered dialing in your car's suspension, tires, brakes - you're now going to have to learn to dial in your car's aero.

Focus more on dialing in your driving skills before worrying about the car's down force.

Skip Barber's intro cars are stripped of aero and run on nongrippy treaded street tires so that drivers learn the basics:

eviltwinkie

I need one as my daily driver...haa

gr8rx

Ive reasearched this a bit and found that A theres either no info written down, or B no one knows.....on specific rx8 kits.....however there r simple things that everyone knows you can do to create more downforce, some of which have been stated, such as lowering the car....Im not sure if your going to be racing in a series that has certain limitations to body work, or are going to be just trying to get best times, like time attack or something....but as far as downforce goes withought actual testing via a windtunnel or crazy computer analysis....the best you could do IMO would be to use the mazdaspeed nose for the cooling with a splitter added, most series of racing limit the distance that the splitter can stick out from the bumper, because the further it sticks out, the more downforce it creates...and the splitter needs to be attached to something other than the bumper so it acts upon the suspension/car and not just the bumper ripping it off. the further the splitter goes underneath the vehicle the better, it smooths airflow, and if it could be made into a complete undertray that would be better, you could also add a rear diffuser, and vortex generators in the rear for downforce/ and less drag....the best wings to use are the APR wings because they have actual wind tunnel testing done on them......with posted figures....unless u get something custom made $$$$....