Help, questions about exhaust velocity??
Help, questions about exhaust velocity?? I'm about to do an exhaust from the headers back on a 95 super coupe. It's a stock motor running on 15psig.
Right now he has 2 2.5" pipes going from the header collectors and Ying into one 3 inch pipe, and they Y again into a pair of flowmaster 40s.
I Figured his corrected air flow at redline RPM was about 575cf/m which means one half of the motor is flowing 287cf/m.
I calculated 287cf/m through a 2.5" pipe is about 140 feet per second. I read that as long as backpressure is relatively low that a smaller pipe with faster exhaust velocity will perform better than the bigger pipe with slower velocity. As long as the velocity didn't exceed 450ft/s.
If I reduce the pipes to 1.75" and 2.5" respectively the new velocity would be around 285 feet per second at redline RPM.
So does the "bigger is better" theory crash and burn or am i spinning my wheels and should I just do the 2.5 into 3 like it is now. Thanks for your time, Matt
Right now he has 2 2.5" pipes going from the header collectors and Ying into one 3 inch pipe, and they Y again into a pair of flowmaster 40s.
I Figured his corrected air flow at redline RPM was about 575cf/m which means one half of the motor is flowing 287cf/m.
I calculated 287cf/m through a 2.5" pipe is about 140 feet per second. I read that as long as backpressure is relatively low that a smaller pipe with faster exhaust velocity will perform better than the bigger pipe with slower velocity. As long as the velocity didn't exceed 450ft/s.
If I reduce the pipes to 1.75" and 2.5" respectively the new velocity would be around 285 feet per second at redline RPM.
So does the "bigger is better" theory crash and burn or am i spinning my wheels and should I just do the 2.5 into 3 like it is now. Thanks for your time, Matt
