Posted by 74merc (IP: 209.149.123.150) on April 09, 1999 at 02:35:50:
In Reply to: Backpressure does not give you more power... posted by T.L. on April 09, 1999 at 00:06:32:
When you free up the exhaust system, the engine can go farther off of less gas, seeing as it doesn't have to force all of the previously combusted fuel out, it flows easier without the backpressure. the engine is running a little "looser" for lack of a better term. Since its running looser or more free or whatever, it requires less gas
to do the same work. If its not under a noticeable load, burning less gas, it is actually producing less torque, until you open the throttle, then it produces more power across the entire rpm range. When you take the car to the track, you're not exactly gonna ease on the throttle, and since its not having all of the backpressure on a better exhaust system, you do have more power and better times. Dual exhaust lets the engine breathe better for better fuel economy and lets more air go through the entire system for more power. Basiclly, its just smart to put dual exhaust on any single exhaust V8 car, be it track or not.
So, you do seem to lose a little low rpm torque because you don't give it as much throttle when cruising 55mph as when you cruised with single exhaust. So you're both right, and you're both wrong.
Check out a Buddy Rawls site for more info on volumetric effiency at
http://www.wighat.com/fcr3/
James
http://members.tripod.com/red74merc/index.htm