dimo61 » Пн дек 26, 2011 12:50 am
The bottom of the car is stock. Stock belly pan, stock exhaust (not used as an exhaust), stock wind deflector panels. Suspension is stock other than springs and struts.
Stock exhaust was designed as an aerodynamic element of the car. If you look at it, the exhaust is wide and flat. Removing it and putting in a full 3 or 4" exhaust would leave large air pockets under the car, allowing air to pack in. This would be very bad at 200+ miles an hour. The decision was made to leave it intact under the car, with the 4" exhaust dumping out just in front of the front doors. Coefficient of drag on an URS4 is .29. Audi did a very good job of making this car stable at speed- Jeff didn't feel like reinventing the wheel and left good enough alone. The front of the car was lowered slightly to give it a rake, and limiting straps were installed to keep the front end from lifting at speed. Otherwise, there are no aerodynamic modifications done. Body wise, the car must stay stock- no wings or splitters are allowed in the class the car is running.
Interesting note- the stock exhaust does not become a restriction of flow until over 500hp. The stock downpipe, at the split, necks down to 2 1/8". Modifying that opening up to full 2.5, and smoothing the transitions into the dual 2 1/4" tubes allows the stock exhaust to flow as well as a full 3" exhaust. Jeff's road car has this modification with positive results. My downpipe will be going to him in the very near future for this mod- I'll report back with the results.
The bottom of the car is stock. Stock belly pan, stock exhaust (not used as an exhaust), stock wind deflector panels. Suspension is stock other than springs and struts.
Stock exhaust was designed as an aerodynamic element of the car. If you look at it, the exhaust is wide and flat. Removing it and putting in a full 3 or 4" exhaust would leave large air pockets under the car, allowing air to pack in. This would be very bad at 200+ miles an hour. The decision was made to leave it intact under the car, with the 4" exhaust dumping out just in front of the front doors. Coefficient of drag on an URS4 is .29. Audi did a very good job of making this car stable at speed- Jeff didn't feel like reinventing the wheel and left good enough alone. The front of the car was lowered slightly to give it a rake, and limiting straps were installed to keep the front end from lifting at speed. Otherwise, there are no aerodynamic modifications done. Body wise, the car must stay stock- no wings or splitters are allowed in the class the car is running.
Interesting note- the stock exhaust does not become a restriction of flow until over 500hp. The stock downpipe, at the split, necks down to 2 1/8". Modifying that opening up to full 2.5, and smoothing the transitions into the dual 2 1/4" tubes allows the stock exhaust to flow as well as a full 3" exhaust. Jeff's road car has this modification with positive results. My downpipe will be going to him in the very near future for this mod- I'll report back with the results.