General discussion about exhausts

[saxophonias]

The number of mufflers, the size and length of the exhaust and the flow are very significant issues when it come to serious tuning.

[saxophonias]

What exhaust tubes are you using? I first had a 50mm tube with 2 mufflers which i found very good for torque! When i swapped the intake and exhaust manifold after a short time i increased the piping to 55mm. The engine responded great. Power throughout the powerband.

[Dodo Bizar]

I got 55 mm since 2002. We all know that I got enough power with that. Never changed for smaller. Have seen 50mm systems having a hard time getting to 100 bhp/litre, performance over 7000 rpm seemed bad.

[Law_]

55 means 55mm in the Exhaust Header also right?

[Dodo Bizar]

Hmmmm.... think header actually had a smallest 48mm part. Not sure if its only local at the cat flange or entire tube... at least original gasket can be used, which is 50mm inner diameter if I am correct. So tubing is < 50 there. Next time I place cat I try to see.

[Law_]

ok, but my Cat is far from the engine , not at the header as some car models just to clarify. Yours also right?

[saxophonias]

Correct. It's not on the exhaust manifold like d15z6 (ek3).

[hondaNickx]

It all depends on what header you're using .Look at Bisimoto's STock D15 engine with 2.5" exhaust and cold air.He made 16WHp gain with his custom v2 header and a lot of torque gains too .And that's with a 2.5 exhaust!
I'm using 2.5" all the way ...

[Dodo Bizar]

Just 2.5 inch all the way hehe... to me that sounds big man .
That is what's under my B16B.

[hondaNickx]

Just 2.5 inch all the way hehe... to me that sounds big man .
That is what's under my B16B.

It is Big for a little engine but like i allready said if you are using a Great header it extracts a great amount of gas out of your cylinder and you def can use that 2.5" exhaust.If your using a general 4-2-1 exhaust you'll be better of with 55mm or so.