Turbo Back Pressure...chime in experts.

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Oct 27, 2003 | 09:59 AM

Shinobi'sZ

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From: Forced Induction Heaven

Turbo Back Pressure...chime in experts.

I am just curious how much backpressure is too much for 12-15lbs of boost? Is it 3:1????
Thanks

Oct 27, 2003 | 12:12 PM

MIGHTYMOUSE

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From: Virginia

it doesnt depend on your boost pressure but instead the exhaust layout(tubing size etc.) power range,displacement, turbine AR and that sort of thing..

i reccomend checking out 'maximum boost' in your local bookstore.. i recall anything over 2:1 being too much for a given application..

fwiw lots of race cars run lower exhaust psi than intake psi.

Oct 27, 2003 | 01:08 PM

gogogadgetcar

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From: malmstrom Air Force Base, Montana

what he said

Oct 27, 2003 | 01:40 PM

JimmyKash

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From: Chi-Town

Quote:

Originally Posted by MIGHTYMOUSE

2:1 is about where you want to be.....anything under that and thats great but it is hard to do with the size of the given turbo you plan to use.

Also, the reason why most racecars have lower exhaust pressure versus intake pressure is because of the size of the turbine wheel, housing, and a/r ratio. Its a lot easier to expel exhaust gasses outta a 5" thumper flange than it is a T04 3-3.5" flange.

If you can get around 2:1 you'll be fine.

Oct 27, 2003 | 11:07 PM

Jammer

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Max Boost hint # 1 : Any backpresure is your enemie

, Buy the book, it is well worth the $35 at Barnes and Noble, Book # 0837601606, it cant get any easier now!

Oct 28, 2003 | 09:35 AM

Shinobi'sZ

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From: Forced Induction Heaven

Quote:

Originally Posted by JamMasterJ

Max Boost hint # 1 : Any backpresure is your enemie

, Buy the book, it is well worth the $35 at Barnes and Noble, Book # 0837601606, it cant get any easier now!

Thanks I will check it out at B&N.
The setup is currently making 12lbs of boost with 35lbs of backpressure. However, the boost also drops off from 12lbs to 10lbs at 6000rpms. I am assuming it is a backpressure issue. Before it was making 45lbs of backpressure and dropping from 16lbs to 8lbs.