Gtr Engine Pipe Design

[Scooby]

Guys;

Got a few questions on engine pipe design ie dump outlet to collector on a GTR.

Length

My understanding is that engine pipe runner length is not critical. A bit like after the headers on a n/a motor. However some manufacturers make equal length runners (with a big ass bend to create the equal length on the rear pipe) and others do shortest path. Nismo and Fujitsubo do both and the standard ones are shortest path. Others like Veilside go to amazing lenghts to create equal length. The rear pipe outlet radius on the equal length ones, due to the size of the bend, means the inluded angle on the collector seems too large.

Diameter

CES make good exhausts and they use 75mm or greater engine pipe diam on their comp engine pipes. Most manufacturers use smaller diam into a 75mm collector. CES swear that they get good results from going larger but can't say how much. Anyone done any testing?

Flex joints

I know what they do but there are designs that either use them or don't. I've not heard of anyone having problems because they didn't use one on a GTR, can anyone share their experiences here?

Regards

[Beer Baron]

flex pipe is not as big a concern on a North South engine config like the GTR, but they are vital on a East west style engine like an evo etc as the engine rocks back and forward under hard acceleration and braking. they are still worthwhile having i reckon, as the side to side movement could still be a proplem without one.

as for the other questions, i'll be interested to hear some answers.