Ok I have talked to a few mechanics about this and none of them have ever had a definite answer to my question. Why do you NEED backpressure on an N/A application? I understand on forced induction applications but still haven't figured it out for N/A. If you have a straight through design why would you want something restricting airflow? Thanks in advance!

 

5 psi.... according to the companies that sellsthe test device....

 

The correct answer is Exhaust velocity...the speed the exhaust moves. A larger pipe will result in a slower velocites.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by YoungKadafi &raquo;</TD></TR><TR><TD CLASS="quote">The correct answer is Exhaust velocity...the speed the exhaust moves. A larger pipe will result in a slower velocites.</TD></TR></TABLE>

slower velocities at x rpm, but may result in higher velocoities at higher rpm, engine displacement, compression, how fast the engine revs all play a role.

 

ahah you NEEED backpressure what the expletive you guys are talking about.
Check on the net for VALVE OVERLAP
If you don't have backpressure, at low rpm when the intake and exhaust valve are open "OVERLAP = the two valves are open for a small laps of time" you're mix of air/gas will go out at the exhaust because it will have some kind of "vacuum" in the exhaust line.
I don't know if you understand what i just said but i'm not english so go read about VALVE OVERLAP, don't put 3" exhaust on a 100 hp , you will loose torque at low rpm ... it's prouved.