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Old 05-14-2000, 07:43 PM   #1
Sean McElderry
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Member#: 526
Join Date: Nov 1999
Location: Beaverton, OR, USA
Vehicle:
1995 Supra Turbo
Red

Question Exhaust + Turbo + Boost + Performance???


Hello everyone. I've decided to take the plunge and get the Minnam Stage II turbo kit. My dilemma is here: I am unclear on what an exhaust will do to the performance. In more detail:

If I get a 3" pipe from the cat back to the muffler, and I get a straight-thru muffler, the car should have enough room to breathe, right? Now, in the latest SCC, when they switched to a performance muffler, the boost went up 2psi. Why?

That's my first question. Secondly, if I were to keep the stock exhaust, can I simply tune the wastegate setting to provide the same amount of power (as with a performance exhaust)?

If this is so, I don't see the advantage of going with a larger pipe and performance muffler. Is there one?

Thanks, guys.

Sean
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Old 05-14-2000, 07:45 PM   #2
MattC
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Member#: 158
Join Date: Aug 1999
Chapter/Region: NESIC
Location: CT
Vehicle:
2011 STi
PBP 1999 2.5RS RBP

Exclamation

I am running the Rallispec exhaust in 3", and have no problems with it. The car pulls much harder up top, and I don't think I lost much if anything down low. I am running a Minnam Stage II@7psi presently.

MattC
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Old 05-14-2000, 07:57 PM   #3
Strepto
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Location: San Antonio, TX
Vehicle:
2001 Arctic White
Camaro SS #1800

Post

If you keep the stock exhaust the amount of back pressure will be enough to hinder your performance. Turbos need a larger pipe to flow air more easily. If you have back pressure on a turbo it can't spool easily, therefore hindering performance. With a turbo you're pushing more air and it needs a place to go. If the pipe is too small the air gets "stuck" causing back pressure because it can't move at a quick enough rate through the pipe.

This is my understanding of why you need a larger diameter exhaust on a turbo system. It's probably not the best explaination explaination, and I'm sure others will help out.
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Old 05-14-2000, 08:07 PM   #4
cOz
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Member#: 576
Join Date: Nov 1999
Location: Houston, TX, USA
Vehicle:
1995 Volvo 850 Turbo
Dark Green

Post

With a free flowing exhaust like rallispecs it will be easier to keep your egt's down and help prevent detonation and parts of your engine being overheated, melting becomes a problem if they are to high.

cOz
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Old 05-14-2000, 08:52 PM   #5
8Complex

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Chapter/Region: MWSOC
Location: Schaumburg, IL
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16 WRX (white)
04 FXT (red)

Post

With the less backpressure you are allowing the turbo to spool easier creating less turbo lag and the turbo will heat up less. The best my old turbo Volvo ran was when the cat. rotted and fell off leaving a 6" section of pipe out of the turbo pointing straight to the ground (note: loud).
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Old 05-15-2000, 07:06 AM   #6
Sean McElderry
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Member#: 526
Join Date: Nov 1999
Location: Beaverton, OR, USA
Vehicle:
1995 Supra Turbo
Red

Question


Thanks for the responses, guys. I've heard the exhaust that Minnam uses on their turbo systems. For some reason, it sounds like it's backfiring all the time (under hard runs). Is there a reason for this? It's much louder than your typical gurgle/pop.

Thanks!

Sean
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Old 05-15-2000, 03:04 PM   #7
Sean McElderry
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Member#: 526
Join Date: Nov 1999
Location: Beaverton, OR, USA
Vehicle:
1995 Supra Turbo
Red

Question


Anyone?
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Old 05-15-2000, 03:55 PM   #8
MattC
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Member#: 158
Join Date: Aug 1999
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2011 STi
PBP 1999 2.5RS RBP

Post

My car burbles and exibits small backfires when off the throtle. Sometimes when I am shifting through gears you will hear a quick POP! Never while I am on the gas tho. I personally love the sound. It scares the hell out of the person you are about to race. VROOM! VROOM! POP! POP! POP!
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