Who's had success with a 2.5" exhaust turbo m20

[nando]

semantics. 3" isn't too big. a lot of guys go 3.5" or 4" depending on their turbo.

2.5" exhaust has about the same cross sectional area as a stock M20B25...

[Jaxx_]

Bigger DP = quicker spool time and harder initial kick. That's my personal experience and the general consensus from others who have upgraded on their vehicles.

don't get it twisted -- you can have a longer spool and less power if you go too big. the loss is small and hardly noticeable, but it is there. we're talking like 3whp on the dyno.

[einstein57]

Bigger DP = quicker spool time and harder initial kick. That's my personal experience and the general consensus from others who have upgraded on their vehicles.

[The Humjet]

I think that's the way to go. 3" right through is really ideal, and if you ever feel the need to upgrade later down the track your exhaust will able be to stand up to the task

[Jaxx_]

I would do 3". most manufactures that have 2.25-2.5" are around 200-250bhp. those are non performance applications and a bigger downpipe will give you more overhead.

[jaywood]

I'm still going back n forth, but I think I've decided the 3" is better. There's no reason for me to not go 3". The current downpipe is ugly anyways.

I'm going to get an assortment of 10 mandrel bends on eBay, and 8 feet of straight pipe.

As far as everything else goes: 1 resonator, 1 flex pipe (length?), summit turbo muffler.



I think it will sound pretty nice. I've read nothing but good things about the turbo muffler. It's pretty cheap too ;)

[Tchao]

You wont loose anything. Theres no reason for the downpipe to be bigger than the outlet on the turbo.

Thats absolutely incorrect.

Like others have said, you rather 3" DP and 2.50 the rest.

[jaywood]

You wont loose anything. Theres no reason for the downpipe to be bigger than the outlet on the turbo. Exhaust cool down on its way out and takes less room so you really dont need a big pipe at your numbers.

That's all I needed to hear.

I like explanations.

Thank you

[Kvasi]

Maybe this will help people:

I'll be running ~10 lbs of boost on a t3 turbo. I'm looking for roughly 250 hp.

This isn't an all out performance car. It's my dd.

I know 2.5" will work. My question is, how well will it work? What performance gains am I losing (if any) from not going 3"?

You wont loose anything. Theres no reason for the downpipe to be bigger than the outlet on the turbo. Exhaust cool down on its way out and takes less room so you really dont need a big pipe at your numbers.

[Toadleg]

electric cut outs are nice if your concerned about clearance. 3 inch down pipe cut out than 2.5 out the back or smaller..... my two cents

[jaywood]

Maybe this will help people:

I'll be running ~10 lbs of boost on a t3 turbo. I'm looking for roughly 250 hp.

This isn't an all out performance car. It's my dd.

I know 2.5" will work. My question is, how well will it work? What performance gains am I losing (if any) from not going 3"?

[jaywood]

How is it easier?
You are building an exhaust....I just dont get why people do shit the wrong way, or even ask for second opinions on the wrong crowd just to get an answer they wanted to hear.

FYI the downpipe is the easiest part of the exhaust.



The OP should of asked: Hi Im making an exhaust from scratch for my turbo M20. Should I do or 2.50 or 3.00? My ghetto kit came with 2.50 down pipe.

It's easier because I have the downpipe already made.


Correct ;)

[Tchao]

How is it easier?
You are building an exhaust....I just dont get why people do shit the wrong way, or even ask for second opinions on the wrong crowd just to get an answer they wanted to hear.

FYI the downpipe is the easiest part of the exhaust.



The OP should of asked: Hi Im making an exhaust from scratch for my turbo M20. Should I do or 2.50 or 3.00? My ghetto kit came with 2.50 down pipe.

[jaywood]

I'm going 2.5"
It'll make everything easier, and I'll have more ground clearance ;)

[Kvasi]

2.5" will do up to around 400hp.