Thread: Gt30-76r
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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269

Interesting info. What HP is that at the line you calculated? Not my area.

Per the Garret site:

•What is my mass flow rate? As a very general rule, turbocharged gasoline engines will generate 9.5-10.5 horsepower (as measured at the flywheel) for each lb/min of airflow. So, an engine with a target peak horsepower of 400 Hp will require 36-44 lb/min of airflow to achieve that target. This is just a rough first approximation to help narrow the turbo selection options.
If this is true that should put the GT30-76R right in the sweet spot at TQ peak and still be at about 75% efficiency at 400hp.

I am not an expert but I have never see anything that Porsche every went over .8 bar (euro spec to .85 bar) on any of there cars. The exception being a hand full of special wish cars with adjustable boost and maybe the special 3.3 TurboS. Not the S2 or 3.6S.

There was a Road and Track article that I believe mislead some that a .9 bar spring was an option on the 3.6S.

I suspect the K27-7200 and 3.3 CIS fueling both had about the same design limits.

Per Bruce Anderson's book on modifying Porsche's a 3.3 CIS turbo with ports, intercooler, and SC cams should not exceed .9 bar if run on the track due to fueling and thermal limits. In this configuration it was about a 390-400chp car. 1 bar seemed acceptable for a street car duty.
Old 10-20-2010, 08:12 PM
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