I'm talking about cars in general, not specifically the Z32.

 

If you fit a higher flowing aftermarket exhaust to a turbo car, what are the pros and cons?

 

I'm guessing more power is an obvious one - but it it right through the rev range or just at the top? Can you loose bottom end power?

 

What are the down sides? Can it cause damage to the turbo(s) somehow?

 

Thanks in advance...

 

:bow:

you can lose (a lot) of bhp if the pipe is too big...the back pressure is helpful in most performance engines so i've read and been told by mechanics...etc...its all a compromise to be honest...looks, sound, gains (de-catting etc)...they come at a price to be paid somewhere else in the chain

If i am correct its not so much of an issue on Turbos but i know on N/A's you need to get the size and length correct etc. as you need just the right back pressure and so on. however on a turbo the turbos create a lot of back pressure (think its about 20psi) so a free flowing is best.

 

so in simple

 

n/a = needs x backpressure

turbo = as free flowing as possible.

 

sorry if i am wrong but thats how i think it works from what i have read. Also know the lengh of inlet manafolds also makes a difference but thats another topic.

Volumetric efficiency

 

The faster the air goes in the faster it goes out then the faster the air goes in.

 

If you slow the air down for what ever reason then you won't get the turbo spooling as well, but you do need back pressure on an NA so the new charge is not pushed striaght through to the exhaust.

 

Now you can get all complicated with cam timming and valve overlap effecting the scavenge effect of the clean charge and, well it goes on and on.

 

But I would say that an exhaust on a turbo engine would need to be as unrestricted as possible.

Interesting!

 

I'm thinking about this exhaust on the new turbocharged Mini Cooper S

http://www.millteksport.co.uk/product.news.read.cfm?articleid=26

 

Guys on the Mini board seem to think a power increase from 175 to 202bhp is unlikely. Any thoughts on that?

 

ps - I'm not going to buy a Mini! Just interested.

you can lose (a lot) of bhp if the pipe is too big...the back pressure is helpful in most performance engines so i've read and been told by mechanics...etc...its all a compromise to be honest...looks, sound, gains (de-catting etc)...they come at a price to be paid somewhere else in the chain

 

Keeping back pressure is more of an issue for an N/A car.

 

With a turbo engine, it has been proven that the less restrictions = more performance.

 

So on a ZX TT, the bigger bore and no cat exhausts will make the car quicker and more responsive throughout the rev range.

 

Richard :smw:

i think i'm right in thinking that the turbos provide the back pressure, by taking exhaust back pressure off you decrease the amount of force needed to spool up the turbos thereby freeing up some power (about 25-30bhp on stock turbos)

 

X flows behind the turbo also give benefits of less turbulence and quicker spool i remember chunk telling me

check this out

 

I've seen a similar set up like this on an mr2 turbo, when he opened his it roared like a roar-y thing,

 

guy claimed he could feel the extra power :bow: