Turbo exhaust ????

[Eddie Wilson]

Has anyone seen any performance difference in reducing the exhaust outlet diameter on a large single ?

I run a Precision 101mm with a steel 5 inch exhaust.

I plan on building a all aluminum exhaust system to reduce weight.

I was thinking of reducing the diameter from the 5 inch to 4 inch, but I dont want to hurt performance.

[wheelie]

Originally Posted by Eddie Wilson

Has anyone seen any performance difference in reducing the exhaust outlet diameter on a large single ?

I run a Precision 101mm with a steel 5 inch exhaust.

I plan on building a all aluminum exhaust system to reduce weight.

I was thinking of reducing the diameter from the 5 inch to 4 inch, but I dont want to hurt performance.

On a 101, you may see a little more out of the 5", and it will hold up better in aluminum. I'll send you a PM, I have a few ideas for ya.

[DrTurbo]

Originally Posted by Eddie Wilson

Has anyone seen any performance difference in reducing the exhaust outlet diameter on a large single ?

I run a Precision 101mm with a steel 5 inch exhaust.

I plan on building a all aluminum exhaust system to reduce weight.

I was thinking of reducing the diameter from the 5 inch to 4 inch, but I dont want to hurt performance.

Ideally you want to run 1.25 X turbine exducer diameter. Not always possible, but its nice if you can. I don't think you will hurt performance much...all depends on the length.

[Eddie Wilson]

What is considered too long? I have mine dumped behind the front tire.

[TubingJon]

The 4" will definately take up less room.

[Joe @ Tempest]

put a pressure sensor in the exhaust and see where your at.

[redvictor]

How much do you reckon these downpipes are restricting me then Joe?

[Joe @ Tempest]

is that an electromotive DFU i see?

i personally have not gotten around to doing any testing on that stuff as most of the cars we work on we can fit a 4" exhaust/downpipe pretty easily. my buddy works at a shop with an engine dyno and have seen 25-26psi pressure in the downpipe on a 3" exhaust.

ive done a lot of 2.5" to 3" before and after stuff, and its typically 60-100 horsepower gain on a turbo in the 61mm range. again its all high reving 4 cylinder stuff though.

[Joe @ Tempest]

this is the only thing i had on this computer




if i remember correctly this was a 61mm, 2.2 motor, 8500 rpm, 2.5" before, 3" after. spring pressure no boost controller even installed. roughly 10-11psi. no adjustments to the tune, hence the big dip on the low end.

[redvictor]

Originally Posted by Joe @ Tempest

is that an electromotive DFU i see?

i personally have not gotten around to doing any testing on that stuff as most of the cars we work on we can fit a 4" exhaust/downpipe pretty easily. my buddy works at a shop with an engine dyno and have seen 25-26psi pressure in the downpipe on a 3" exhaust.

ive done a lot of 2.5" to 3" before and after stuff, and its typically 60-100 horsepower gain on a turbo in the 61mm range. again its all high reving 4 cylinder stuff though.

Yep,it's a TEC3R system. The downpipe is 4.5" but the bottom of the bend,well....it doesn't. It's 90 deg vertical immediately after the turbo housing.
I have 44psi of back pressure at 26psi of boost and bigger housings have made no difference whatsoever.
I'm convinced that the ex flow out of the housing cannot get out fast enough..
Here's a vid from the dyno 3 years ago.Look how the heat goes from the housing.I think the flow is choking from the wheel back..
http://videos.streetfire.net/video/E...R-by_39705.htm

[bags50lx]

Originally Posted by wheelie

On a 101, you may see a little more out of the 5", and it will hold up better in aluminum. I'll send you a PM, I have a few ideas for ya.

Care to share your ideas???

[card counter]

Originally Posted by redvictor

Yep,it's a TEC3R system.

[Frank02L]

We have a 4.5" aluminum on ours. Approx 5-6'