Originally Posted by heeman10
Originally Posted by Mike Rainbird
Importance and effects of: Length, size (diameter), rotational firing order etc.
Discuss
.
Lazy bastard!
I'd be saying the lower the backpressure the better. The turbo'll be creating backpressure as it is, so the shorter the exhaust and the bigger it's diameter the better, ie fat screamer pipe would be the ultimate. Am thoroughly prepared to accept that as poor theory if someone can prove it
4 stroke petrol engines have no benefit in having any "back pressure" that im aware of.
Any resistance to flow is only ever going to lose you power IME.
you need an appropriate sized pipe (especially on an N/A car) to keep gas speeds up and hence help to scavenge the last fiew bits of exhaust gas from the chambers, but thats actually a negative back pressure at that point in the cycle (due to the vacuum created behing the gasses as they go up the pipe)
I cant picture in my mind ANY point in the cycle where having positive back pressure is actually a good thing?