NA and Turbo exhaust differences?

[Mondo]

I'm looking to find out what differences there are between exhaust systems for turbo'd cars and naturally aspirated ones. I know all about the manifolds - I'm wondering if there's any differences in backbox design, more than anything.

The reason I ask is this: I mated a Blitz Nur Spec backbox (from an ST205) with custom 2.5" pipework to the standard Beams centre section (2.25" pipework) and I can't help but think that she's down on power ever since I did that!

I appreciate that I may have simply "gotten used" to the power of the car, but it does feel noticably less rapid since the exhaust was modified? Could it be the 2.5" pipework reducing the back pressure? Is the GT-Four rear box too free-flowing for an NA engine?

Anybody got any thoughts please....?

[digs]

I am probably completely wrong here but don't you need stockish levels of back pressure for n/a ? Unless you muck about with air/fuel mix.

i am 99% sure someone who knows what they are talking about will come on in a minute to say "what the hell..."

EDIT: interesting.. http://www.tundratal...sure-myths.html

talks about flow velocity as opposed to back pressure

http://www.pistonhea...c.asp?t=1203932

more reading

Edited April 18, 2013 by digs

[paulgtt]

Blitz exhausts for st205 are 2.75" bore, maybe its too big!!

[Limeymk1]

Different tuning requirements completely for turblo and n/a exhausts, from what I understand for a tubby you need as little restriction as possible so a big fat pipe is ideal.

For N/A it's a LOT more complicated, the length and bore of all the pipework is very important as there is a reverse pulse that travels back up the pipe to the engine and getting this right effects exhaust gas scavenging from the engine. There's more to it than this but I'd have to refresh my memory on the technicalities.