Exhaust flow talk

[NoHachi]

Ok Mux, time for a split....cause here I go again...

JTA: you are stating as fact something which is one of the biggest urban myths going round under the new breed of NA fanboys. The "need backpressure myth" is the biggest piece of BS on carforums today.

Just THINK about it for a second..what is an engine? An air pump. When does a pump work best (aka most cfm)? When the pressure difference it has to overcome is the smallest.

Now, all the flow/velocity etc parameters are already set down by the header. Headers do create a "backpressure" kind of effect called scavenging..type it into google and I'm sure someone has written it down in understandable terms..I'm way to deep into the mixture of acoustics and thermodynamics to write down something you guys would understand.
After the header you want as little backpressure as you can get...

So why do some fart can exhaust lose some (very minor, its still 99% BS!!) low end power? The problem lies in the connection of the XX diameter header/midpipe, to the XX+A diameter exhaust..There is a step that is created that creates a lot of drag, especially at lower flow speeds (large eddies)...If you create a smooth transition between the fartcan and in between pipe, the engine will produce more power over the ENTIRE revband..

But don't take my word for it..I'm just another engineer...if you google on any combination of words in the text above it should come up with more then enough interesting information..

Please remember people...I am not a good source for automotive knowledge, and some pimpled benchracing teenager who spends more time on a forum then actually racing certainly isn't(I'm not referring to you JTA, but people all over the world). Make sure to doublecheck your facts on some "known good"sites like How stuff works etc etc...stop this kind of misinformation from being spread!