TudorMiron

What is the difference in downforce provided from GrandAm bumper/splitter and standard Cup front bumper? Is there a gain with GrandAM config?

I would guess that GMC James might know as he has vast experience with both. But is there any measured data? May be not wind tunnel but DA measured?

Thanks
Ted

Glen

I have used the front splitter like the one pictured here and its result was amazing as far as front grip.

http://www.google.com/imgres?imgurl=...w=1509&bih=842

I am running a stock car in IMSA this year so I cant run that splitter and the difference in front grip is significant. It also allows You to run more rear wing for more downforce in the rear without losing front grip.

My spare one is available and works with the stock nose if someone wants one.

TudorMiron

Thanks Glen,
Would you pm me the price? Does it have flat floor as GA splitter?
I understand that you FELT the difference. Have you ever bothered measuring downforce with susp. pots?

Thanks
Ted

mobonic

I agree with Glen 100%,

I had this done to my car along with RSR front ducting and WOW, understeer virtually GONE, and now I have upgraded to a 2010 cup wing!

But 1 offroad excursion and the splitter is basically toast, 100% carbon Fiber and not cheap!

mobonic

no 100% proof, but if they did not work so well why would the be illegal ????

I know these are only currently legal in grand am and WC.. and I heard in certain alms classes

TudorMiron

Thanks Mobonic.
Does it have flat floor extension like GA splitter? Source?
But judjing by you 2nd post it seems like it sounded like I doubt that it works. That’s probably because of my poor English. Please excuse me if that was the case.
I’m a race engineer and designer. I KNOW that it works – no doubting your words here. It’s just that obsessive monkey in my head always wants to know – how much exactly?
Thanks
Ted

Rickard 993 Turbo

What RSR ducition, a RSR have a totaly diffrent ducting..

Glen

Ted, I understand, never had shock pots on the car. Perhaps a GA team could help who has run both? I loved it because I could crank more corresponding rear wing into the car without the dreaded high speed push showing up. Regarding price, whatever You think is fair is fine, its got a scuff or two but will easily mate up to a factory bumper and yes it has the Carbon flat floor with the 2 channels/ducts for brake air.

Cory M

If you checkout the Dec 2010 issue of Racecar Engineering they do a windtunnel test of a 997 RSR with and without a splitter that is similar to the GrandAM unit. The overall downforce gains and shift of % load to the the front wheels was very significant with a simple flat 75mm splitter. One wonders why the car was homologated without one (although the 2011 RSR does have a more traditional splitter). Not an apples to apples comparison with the one you guys are talking about but interesting related info anyway.

Leigh2

Cory would it be possible to post a picture of that 75mm splitter???

claykos

I would love to get a copy of that article...

Cory M

The splitter was your basic flat piece of carbon fiber attached to the lower lip of the bumper, very simple. I'll see if I can scan the article.

The Aerobytes column has been pretty good lately, with full scale tunnel testing of production racecars like F430, lotus, and RSR. A lot more directly applicable to our kind of racing than the open wheel stuff he often talks about.

You can get an online only subscription at a reduced rate that I believe gives access to older issues.


Here is a pic of the new RSR for reference:

http://www.kilometermagazine.com/art...ar_Debuts.html

analogmike

I have a used '08 Grand Am front end that needs some work (splitter was ground down too much over curbs)




In 09, (wider bumper, requires GT3 cup S fenders) they used a piece of wood for the splitter so it's cheaper and more durable than CF. Also you can slide it for adjustments:

TudorMiron

Thanks Cory,
Got to check it. Simon is a smart guy. I did some CFD (single seaters) work for him. He works a lot with historic single seaters and when he does some aero work for his clients it often becomes material for his articles. BTW, I used his rear wing profile on modified Dallara F3 and its L/D ratio was some 18% better than original.
I highly recommend his aero book – very good start for learning this stuff and easy to read. Than go to Katz book.

Thanks
Ted

TudorMiron

Mike,
I like that wood plank thing. Cheap and easy to replace. It seems to me that Getty sells older version without wood splitter. http://www.gettydesign.com/997_coachwork.html#splitter

Would you share a sourse for 2009 variant?

Thanks
Ted