Turbo Exhaust Systems

[MikeM 5]

I have done a search and read through the various articles discussing options for exhaust systems for the 2 litre 8 valve turbo engine.

It is apparent that there can be some issues with smoking on idle if there is not enough backpressure in the system. A few people seem to mention fitting a catalytic converter to solve this, but is seems as if they did not have a centre silencer in their exhaust systems. So my questions are -

 

I have a magnex stainless steel system, with a midbox and backbox - will this provide enough back pressure?

Or will I need to put a catalytic converter in the system aswell?

 

Cheers

Mike

[Tom Fenton 1,542]

I use a 2" stainless Magnex system on my turbo 205 with no problem. I made my own 2.5" downpipe.

[welshpug 1,661]

surely if a turbo smokes, it's goosed, nothing to do with the exhaust.

[MikeM 5]

Thanks for the replies chaps! I shall go ahead and fit my magnex as I had planned then. Thats what I thought too welshpug, not quite sure what the crack is with that!

cheers

[wicked 103 3 Cars]

Not completely true; if a turbo smokes at boost, it's goosed.

 

But at idle, there won't be pressure on the shaft (towards bearings) from the compressor side and the pressure on the shaft from turbine is related to the pressure drop over the turbine. And that increases with a large exhaust. (= more pressure on the seals -> only leaking if pressure is applied on the seals)

I've seen a turbo smoke at idle with a big exhaust, but with smaller diameter exhaust, the smoke was gone....

So the turbo was not in top condition, but still properly boosting and usable.

[MikeM 5]

Thanks for that Wicked, I now understand the issue. I will see how I get on with the 2" magnex system with no cat. I shall report back and let you know if its ok or not however, this may not be for a few weeks yet!

 

Cheers

[wicked 103 3 Cars]

2" is not really big...

 

Note that under boost, the compressor will push back and the net result is less pressure on the seals.

Edited June 27, 2012 by wicked

[joris_andriesse 8]

2,5" Is better. If you go for some serious power, you might even think of 3"

[1 FAT PUG 39]

think mine is a 2.5 streight thrugh to magnex backbox

[aarontrophy 26]

3 inch all the way

[MikeM 5]

Been a while since I have done any work to the car!

 

Today I am going to re-angle the downpipe but, I am looking for info on how other people have done it before I go and make a mess of my new downpipe! Is is just a case of removing the flange and re-positioning it? Or do you cut the pipe itself?

Any info and pictures would be great.

 

Cheers

Mike

[bassline21 1]

I too would like some info on re angled downpipes. I got a magnet system too which I'll be using with a centre box.

[stef205 92 1 Cars]

There has been a big arguement/discussion on this in the past about diameter of exhaust etc, I think it's down to your own opinion, I went for 2.5" though out on my supercharged gti6. Flow is a major part in exhaust system.