Exhaust Length

[Guest mcramsay]

i have bought a new back box, and new length of 2" exhaust pipe. my plan is to get rid of the old GBSC silencer with welded in CAT, and make up a new section of pipe without the cat with the back box welded onto the end of the pipe. basically the same as the GBSC setup minus the CAT. at the moment i have to set the position of where i want the new back box to go, does it make any difference to how the engine will perform how long the exahust is? if i wanted i could pretty much have the backbox fitted straight into the downpipe (just after the lambda) the length of the new back box would actually fit here, or do i extend the pipework back to where the exhaust would normally sit?

 

i am keeping the old GBSC exhaust pipe with welded in CAT for when the MOT comes around!

[theduck]

Will make little difference either way IMO, and so from purely an aesthetics point if view is go shorter rather than longer.

[Snapperpaul]

The maths for exhaust pipe length take into account cam duration and overlap, primary and secondary manifold lengths collector diameter and length, distance to Can, can length and tail pipe length

You don't need to worry, you can make it any length you like, the only reason to make it a specific length and diameter is to squeeze every last ounce of torque out

[Guest mcramsay]

i didnt think it would make too much difference! cheers guys

[knights_templar]

why do you want to go to the expense of removing the CAT?

[Guest mcramsay]

i would not say it was a great expense to remove the cat from the system.... i made a new section of exahust pipe up which i had left over from a previous project, and 20 quid for a new backbox, which i wanted to change anyway. personally i dont see the need for the CAT, i dont have an MOT for another 2 years. just something i wanted to do on the car to be honest.

[knights_templar]

must admit, old type does look like a snake that has swallowed a rabbit, so take your point :-)

[Guest mcramsay]

Couldn't have put it better my self!