What diameter exhaust for 1.9 TDI?

[Brian of Nazareth]

Hi guy's, just a quickie.
I haven't got my car with me to measure, but I wanted to try and get some stainless ordered for the exhaust.
Got a pd90 but I'm going to be fitting a 130 turbo and a set of 150 injectors.
So. What's the standard diameter of the ANU exhaust (if any different from any other 1.9 TDI exhaust) and what diameter ideally SHOULD I have?

It's going to be straight through apart from the cat, if that makes any difference.

Cheers

[SirDavidAlhambra]

Well sir, Iââ,¬â,,¢m not sure but personally I always think of exhausts as being a bit of a waste of money. Why not get a really big one, ideally made of stainless steel so that it lasts. All they do really is pipe the fumes from the front to the back. Important but annoying really. I think a big one would be better than a small one because the air would pump out with less restriction. Just tell the gaffer at the exhaust place to fit a big one and to do it properly. Make sure you check it while itââ,¬â,,¢s still on the ramp in case he bodges it. For instance a common bodge is to give you a stainless exhaust but then weld on a normal steel mounting bracket which rusts.

[Brian of Nazareth]

Oh yeah. It's definitely going to be stainless, that's what I meant by "I want to try and get some stainless ordered for the exhaust"
It's no going to a garage, it's being made properly by a welder/fabricator mate of mine.

I was looking for the diameter and also if anyone had any input on whether a larger diameter would benefit at all?

[SirDavidAlhambra]

Good choice (stainless) and even better if someone you know and trust is doing it. I canââ,¬â,,¢t see a large diameter exhaust doing any harm providing it all fits securely. My motto when it comes to cars is always ââ,¬Å"bigger is betterââ,¬Â!

I am not sure what the standard diameter is but could you for instance look up the part on Euros and get it from the tech specs there? Thank you

[Brian of Nazareth]

Well, I though that bigger is better. Get the burnt gasses out quicker............ but it would appear that exhausts are a dark art and all is not as it seems.
Been researching a lot and there are a lot of dependants on which exhaust diameter suits the car best.
I can't go through it all, or even remember a lot of what I've read, but too small causes restriction and back pressure, too big causes not enough back pressure to draw the gasses out quick enough.
That's my grasp of the basics, anyroad

[regw]

Its a diesel right ?
Deisel fuel is injected not induced, so all that back pressure/valve overlap stuff is mainly irrelevant
as long as you dont have a ridiculously small diameter exhaust pipe.

[Brian of Nazareth]

Thanks for the info, regw 👍🏻