Benefits of 2.5" diff back - Page 3 - Perth-WRX.com

phizzle · #21 20-09-2007, 11:45 AM

Quote:

Originally Posted by jEstEr?

i reckon at the end of the day, prettymuch anything is better than the restrictive stock exhaust. except maybe a 6" exhaust on a td04

You still need convincing. Batman had a lab and everything

jEstEr? · #22 20-09-2007, 11:48 AM

3 screamer pipes!

phizzle · #23 20-09-2007, 11:52 AM

Quote:

Originally Posted by jEstEr?

3 screamer pipes!

I know lol, what a fukn classic.

tuna · #24 20-09-2007, 11:56 AM

Quote:

Originally Posted by maddog

compared to Michael South ?

ive logged a linear exhast restriction of 3" to 1.5" (the full range of a Varex)
-0.02 kpa (3") to 0.12 kpa (1.5")

data logged at 200 samples per second, barometric at 100.5kpa (stable) exhaust at a consistent temp at 450 degrees celcious (stable), 3750 rpm (stable), consistent 29.5c inlet temps.

Hurtenstein · #25 20-09-2007, 12:58 PM

Quote:

Originally Posted by jEstEr?

3 screamer pipes!

And a pod filter on the roof for direct air intake..

NIX WRX · #26 20-09-2007, 01:06 PM

Either way, Pete hit the nail on the head with his comment. Specific applications needs specific solutions.

As my particular application ATM is about getting as much torque as I safely can from a sub-300HP set-up on an MY03 WRX (balancing that desire with other considerations though - e.g. the *noise* from a CAI), the question around 2.5" diff-backs interests me.

Tuna... I appreciate your input here on this topic too. You sound well-qualified about these sorts of things!

BALISTC · #27 20-09-2007, 01:06 PM

See you guys are missing the point...this is what I'm planning on doing.

1. Fit 2.5" cat-back exhaust.
2. ????
3. Profit.

POLARBEAR666 · #28 20-09-2007, 01:06 PM

Quote:

Originally Posted by tuna

ive logged a linear exhast restriction of 3" to 1.5" (the full range of a Varex)
-0.02 kpa (3") to 0.12 kpa (1.5")

data logged at 200 samples per second, barometric at 100.5kpa (stable) exhaust at a consistent temp at 450 degrees celcious (stable), 3750 rpm (stable), consistent 29.5c inlet temps.

What does that result mean in english tuna? Does it mean that the 1.5" is extremely restrictive or is .12kpa not much?

jEstEr? · #29 20-09-2007, 01:11 PM

Quote:

Originally Posted by BALISTC

See you guys are missing the point...this is what I'm planning on doing.

1. Fit 2.5" cat-back exhaust.
2. ????
3. Profit.

why do you keep stealing my underwear then ?

rspct · #30 20-09-2007, 01:18 PM

Quote:

Originally Posted by NIX WRX

There is no difference in backpressure noted between a 2.5" (R2) and 3" (R1) diff-back system, up to 525HP.

Yeh, real accurate results there haha

. I agree that it would not be in the order of 1 psi difference... It is only a 1-2 m section of exhaust with half an inch difference...

The cat and number of elbows will have the largest effect on back pressure, if the diff back is only section you are changing the diameter.

The most important message here is that it has nothing to do with "maintaining the gas velocity as the exhaust gas cools". There are so many fundamental things wrong with that statement, bernouli would be turning in his grave.