johntorg

Sprint Car Style

johntorg

951ONE: Thanks I'll look in the trick 951 post. Do you have any close-ups of you diffuser? Did you buy it or make it? My car has som crappy looking aluminum back ther now.

Chris: I will look at the rule book I will probably runin NASA GTS4 where we don't need no Steeenkin rules.

HansB

Yes, I have, will post them in the morning.

I sincerely doubt that the car shown in the picture was build this way by Porsche.

95ONE

I made a thread a long while back
Here ya go.

https://rennlist.com/forums/944-turb...t=windgeflaren

future

Thanks Hans and I will touch on your stunning car shortly

Back to post:

Would I be right in saying that the rear diffuser is the same as mounted to this FD3S?



Johntorg - Nice car but that spoiler is tragic – He needs go bolt it to a Supra … Rice style!!!

Let’s take a look at ground effects? I’m sure we all understand that by adding more rear wing will create under steer?

Hans I'm sure will tell you that running a high down force rear wing means that he need to run a square wheel setup to counter act these forces and help eliminate front under steer providing a balanced ideal 50/50 turn-in as he runs very little front down force over stock which would be difficult to achieve without a total front bumper PU redesign as our 951/2 is 90 degrees flat front?!?

A rear diffuser is not worth much without ground effect which starts at the front splitter which I will get to now!

The further forward from the bumper PU the extension of the front splitter the more ground effect you will create (move forwards) and the underside of a splitter NEEDS to be flat otherwise a total waste of time (if not flat creates turbulence which equals uplift – or cavity slow down) hence why the AIR splitter has been so popular and still to this day the best as far as design is concerned for our cars. Faster flowing air under the car and slower over the top, but then the road surface comes into play creating down force i.e the slower the air moves over the top and the more stream line underneath equals down force with minimal drag or ultimate vacuum effect. The lower the car, the more streamline the air under it hence it exits the rear faster than the air over the top creating negative under and positive over pressure. This works in reverse (negative) to a plane wing with has no under surface (or road in our case) other than air hence fast under and slow over creates lift (no channel)! A flat bottom effectively flows air more efficiently with no place to go but out the back (rear diffuser open the gap for quicker expulsion – do not confuse this with our 951/2 stock rear diffuser as some would like to call it – This is an additional spoiler taken from the TVR 390 SE design which soon became the 400 SE – Some engineers say that the Porsche wale tail also came from TVR’s 420 SEAC or armid composite design – Just don’t quote me on that one. The air flowing over the top of the car is hence slower meaning down force. By adding a diffuser to the rear without a flat bottom will have near no effect (with no top wing surface). If you want to argue this then take a look at the Lotus Exige, Ferrari Enzo or even the Mclaren F1 (plus many more super cars including the Carrera GT and F1 motorsport for that matter) which will illustrate what I we are talking about.

Please also remember a splitter is not a canard – Splitter means split air from “top to bottom” however the 993 GT2 did feature a splitter / canard design which worked very well!!!

Canards work differently and are ultimately a down pressure wing to work in harmony with ground effects – Sorry for rambling on but this needs to be understood

So let’s recap – A splitter without a flat bottom is not a splitter – More a front wing if angled but the underside will counteract the benefits. A rear diffuser without a flat bottom from front to back is not 100% effective but more effective than the front splitter I just mentioned!

I don’t mean to ramble on but this is an area I know and work with but anybody who would like to disagree is more than welcome to try and prove me wrong

95ONE

I don't think anyone was arguing?

Yes. As illustrated in the link I posted before. _ Someone posted almost the exact same picture you did. EDIT: Pretty funny. It was me.! And it is made for the FC and the FD. Made by RE-Amemiya. Not cheap though. But a very nice piece. Comes in Carbon fiber also, but the layout is not a dry bagged set-up. So the Fiberglass is right at the same weight, just not the bling.
I just added some support brackets in places. The rear dimensions are almost exact between the FC and 944. That is why is looks like it was made for our cars. And we of course know that the RX7 clearly emulated the 944. Porsche certainly thought so with their lawsuit...they didn't win.

John, PM me if you would like more info on how to obtain the kit without the crazy Amemiya prices. No affiliation. No profits to be made by me. I no longer have an account to sell them.

95ONE

Super Class Rules: Classes GTA, GTB, GT-1 thru GT-6 and GTP-1 thru GTP-6

D. No spoilers, wings, or air dams may be wider than the basic bodywork of the car. No front spoiler or air
dam may have components extending forward of the bodywork with the exception of splitters which
may extend no more than 4" beyond the rest of the front bodywork. No rear spoiler or wing may be
higher than 4’10" from the ground, or extend more than 6" beyond the rear bumper.

johntorg

95ONE, thanks, if you can PM me the information on the diffuser. my car is currently running 265/16s all the way around so it is "square". There is a front splitter that is currently not installed that might make a little more downforce to balance the ricer wing. I am going to run this car for the first time on Feb 21/22 at Roebling and see how it handles without any aerodynamic tweaks. I am looking for some 17X11 Wheels and will go to larger rear tires (more understeer).

Did you ever go with coilpacks on your Motec setup?

Future: Here's a picture of the splitter that came with the car. What do you think?

johntorg

Thanks for the information. With the wide rear fenders, the wing should be legal, as is the spliiter, but I guess I'll have to take it off the roof.

TonyG

You never want to mount a functional wing to the body work. The down force is too great and will distort the body panels.

You always want to mount a functional wing to the chassis. In the case of the 944, it's the rear "frame rails" on each side of the spare tire well, like so:

TonyG

HansB

Found the pictures





Like TonyG said: It has to be mounted on the chassis

A.Wayne

That car was built by Kelly Moss ............has a lot of trick parts ...

Duke

95ONE, which wing do you want? An APR GTC?

johntorg

Hansb and TonyG: Thanks, that's exactly what I was looking for. My car has had the factory diffuser removed and the space filled with sheet aluminum. I would appreciate any comments on whether to reinstall the factory diffuser, go to the setup 95ONE has, or fabricate an aluminum diffuser.

95ONE: Did you have to cut out the spare tire well to install the diffuser?

Thanks to everyone.

95ONE

Spare tire well must be cut.
I do not suggest my wing support set-up. Lots of little things like that were stop gaps for the real thing, and are now gone. I did really like the bridge idea, but difficult. For true performance and reliability, I don't think you can get around bolting to frame through lexan.