J Chen

Hah,
Looks like we're in the same boat. Maths to me always
spelled taboo. I'll do a dyno run before & after NZ.
Will let you know of the results.

NZ951

Good man!

Hey I may be going to China again in a couple of months, I will try and get a stop over in Taiwan instead of Hong Kong and we can have some rice and fish!

J Chen

Hey Man, please do. Let me know
if you're coming.

hosrom_951

Not for German or NZ specs (maybe even Australian?) The exhaust system on my car was never tampered with, there is NO cat/primary muffler, nor is there a third muffler.

J Chen

Hey Hos,
OT question. have you installed the 60-1 hifi ?

hosrom_951

PM sent

Porsche-O-Phile

3" setup (like the SFR) is what I'd eventually like to do - including the downpipe. I believe that alone with a good high-flow muffler like a Borla or something would do wonders and allow me to get the most out of the stock setup. Who knows how long that'll last before I feel the need for a Garrett 35 or something though. . .

Willard Bridgham 3

Based on 500-600 cfm turbo:


The pressure drop from the turbo down-pipe 2.5" vs 3" is approximately 1psi (from turbo to test-pipe).

The difference in pressure drop between 3" and 2.5" from turbo back (test-pipe and muffler ) is approx 1.0 psi.

The pressure drop of the cat is 2.5 psi either 2.5" or 3" pipe.

Total pressure drop decrease is approx 4.5 psi and hp increase is significant and the turbo spools quicker.

J Chen

Hi Willard,
Where did you get this info ? Base on 500-600cfm turbos,
may I ask at what boost level are we looking at & is this
figure based on th 951 engine ?

Willard Bridgham 3

Based on my Silver Rose, measured and calculated pressure drops.

Measured and calculated drops agree very well (+-5%).

Aftermarket turbo, 15 psig.

J Chen

Thanks Willard

J Chen

BTW Willard, I still can't help thinking how
much back pressure is attributed by the
exhaust volume verses turbulance caused
by the axial flow of the turbine.

special tool

Willard - Is this backpressure, or intake manifold pressure?
I have a very different set of backpressure decrease numbers as tested by myself in the exhaust manifold when changing from 2.5 to 3 downpipe back.
I will assume you mean intake pressure.

NZ951

Swanders you are right,

My car had a primary muffler in place of a cat... not sure where Hos got his info.

Thanks for the info Willard. Interesting info! What was the absolute pressure in each states?

hosrom_951

Another rennlister from NZ also confimed the SAME exhaust set-up as i have, and the same for another Autralian rennlister.