Hi guys,

Been reading lots of this forum over the last couple of days, bee quiet at work... Couple of simple tuning queries, there's a lot spoken on the subject of exhausts, is there a thread that explains all this? I'm thinking 5-stud, 3" dia vs 2.5" etc. When I had my Uno Turbo many years ago, I got a stainless scorpion system (with a 4" tailpipe, lol) and noticed the turbo span up a lot quicker etc. It seems there's more to it for the 20v turbo coupe, what should I be looking for?

Also, what is an RSR?

Cheers all

An RSR turbo is a hybrid roller bearing turbo - made from a GT28'RS' and a GT28'R', hence the 'RSR'. Its combines to give fast spool up but high boost.

Chris

Excellent, that's sorted that one out then, cheers, Nobby.

with a turbo car, the exhaust simply needs to get rid of the gas as best it can, so larger is normally better

Clearly you have to consider the noise and the logistics of fitting, but essentially, the best exhaust for any turbo car is as big and short as possible

Best compromise for a Coupe is normally a 3" downpipe using a 5-stud flange straight onto the turbo

Ah, so the 5-stud fitting is cut out any need for a de-cat pipe. Cool, I thought it may have an effect on the pulse reflections for a tuned engine but bigger is better, fair enough.

No Bob.

The standard car has the following in order of output:
- TB28 turbo with v band join on exhaust outlet
- ~2.25" downpipe with v band join, flexi joint then onto 2 bolt flange
- Cat pipe with 2 bolt flange on one end and sleeved pipe on other end
- ~2.25inch exhaust system with 2 big silencers

Modified cars usually have something like this:
- Bigger turbo with a 5 bolt exhaust outlet
- 3" downpipe with 5 bolt flange, flexi joint then 2 bolt flange
- Decat pipe with 2 bolt flange then sleeved pipe
- 3" exhaust system with 1 or 2 silencers

Ideally you want to do away with the restrictions - so v band, the cat pipe and some silencers plus the diameter of the pipe should be slightly larger than standard.

Be aware though that around 2.5 inch exhaust is large enough to support over 300bhp so you don't need 3" if you are looking for little gains.

Apologies, haven't checked back to this thread for a while, many thanks for that Nobby, thats just the sort of detail I was after. One question still, V-band join? That's one term I haven't heard before actually.

Here's a pic of some v band clamps and the bits they join together. If you imagine an exhaust pipe with the solid circlular bits welded on the end, then another pipe with a another end welded on.

Put the 2 pipes together and they sort of overlap a little, then you the clamp fits over the top and they are held together.

These specific v bands on this site are quite small - and are mainly for fitting external wastegates but the same principal applies.

http://www.roadraceengineering.com/parts/wastegates/wg44vbands.jpg

This page has some nice examples of v bands on an exhaust system, on the exhaust manifold 4 to 1 headers joined to the turbo and also on the wastegates (pic 2 and 5). Plus the engine looks pretty nice

http://www.pro-touring.com/forum/showthread.php?t=34318