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wootwoot · 12-26-2012, 02:25 AM

Here is an interesting post from another thread:

"scion/toyota/subaru really did a lot of work on the aerodynamics on this car. They use the stock rear muffler as a defacto diffuser (Mitsubishi did this on the Evo X design work also and they were awarded an international aero award for back in 08). Diffusers act BOTH to reduce drag and increase down force. This effect can favor either side of this equation to produce the results you want. The twins are VERY efficient on fuel this is due in part to the DI injectors and also to careful aero management of the air streaming around the car (and some complain that we didnt get all the cool plastic panels under the car that are part of this package). There is also a track day benefit as the car works well at the track without the addition of any kind of aftermarket aero devices(wings lips spoilers). THIS LACK OF REAR END LIFT IS VERY HARD TO ACHIEVE in a stock vehicle and the OEM designers should be thanked for their hard work. A real world example is the S2000 which NEEDS a wing just to be safe on the track above a certain speed due to rear end destabilizing lift. Sound clip aside, I think Borla should be given credit for trying to maintain the stock aero package. Their diffuser is designed to work as a replacement for the muffler/diffuser used by the OEM designers and this is shown to be needed by many who have changed their exhaust and noticed at the track a increase in rear end dynamics at higher speeds (gets light and more unsettled the faster you go). Oh the borla diffused has slightly more down force and drag due to their vertical elements which promote more efficient emptying of the air under the car (and the faster it leaves the space the lower the air pressure and the higher the down force)."

From here:http://www.ft86club.com/forums/showthread.php?t=23229

My questions are:

1. Is he correct in saying that the exhaust system acts as a diffuser?
2. Has anyone noticed any loss of high speed stability sine changing out their exhaust?
3. Is there a system on the market that takes all this into account?

I plan on tracking my car so this is a concern to me. Also, it could effect freeway driving.

12-26-2012, 02:25 AM	#1
wootwoot Senior Member Join Date: Jul 2012 Drives: FRS Location: Cali Posts: 1,558 Thanks: 188 Thanked 462 Times in 264 Posts Mentioned: 9 Post(s) Tagged: 0 Thread(s)	Aftermarket exhaust and downforce Here is an interesting post from another thread: "scion/toyota/subaru really did a lot of work on the aerodynamics on this car. They use the stock rear muffler as a defacto diffuser (Mitsubishi did this on the Evo X design work also and they were awarded an international aero award for back in 08). Diffusers act BOTH to reduce drag and increase down force. This effect can favor either side of this equation to produce the results you want. The twins are VERY efficient on fuel this is due in part to the DI injectors and also to careful aero management of the air streaming around the car (and some complain that we didnt get all the cool plastic panels under the car that are part of this package). There is also a track day benefit as the car works well at the track without the addition of any kind of aftermarket aero devices(wings lips spoilers). THIS LACK OF REAR END LIFT IS VERY HARD TO ACHIEVE in a stock vehicle and the OEM designers should be thanked for their hard work. A real world example is the S2000 which NEEDS a wing just to be safe on the track above a certain speed due to rear end destabilizing lift. Sound clip aside, I think Borla should be given credit for trying to maintain the stock aero package. Their diffuser is designed to work as a replacement for the muffler/diffuser used by the OEM designers and this is shown to be needed by many who have changed their exhaust and noticed at the track a increase in rear end dynamics at higher speeds (gets light and more unsettled the faster you go). Oh the borla diffused has slightly more down force and drag due to their vertical elements which promote more efficient emptying of the air under the car (and the faster it leaves the space the lower the air pressure and the higher the down force)." From here:http://www.ft86club.com/forums/showthread.php?t=23229 My questions are: 1. Is he correct in saying that the exhaust system acts as a diffuser? 2. Has anyone noticed any loss of high speed stability sine changing out their exhaust? 3. Is there a system on the market that takes all this into account? I plan on tracking my car so this is a concern to me. Also, it could effect freeway driving.