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fredmeister fredmeister is offline
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Join Date: Oct 2002
Location: Baltimore, MD, USA
Posts: 2,232
Originally Posted by 911st View Post
Here are a couple of clues I see.

The factory 3.0 turbo w/o an intercooler targeted a ECR of about 10/1. The 3.3 with an intercooler added came in at about 10.75. Assuming Porsche was targeting the same margin of safety, the early IC allowed Porsche to reach about .75 higher ECR.

Take that 3.0, add a good intercooler and run it at 1 bar boost and it should be running an ECR that is the same as the 3.3 at .8 bar boost.

A 3.3 with an efficient turbo, larger efficient IC is felt by most to be ok at 1 bar boost. That puts us at about a 11.5/1 which is just a bit more than a normally aspirated 993.

Some of the big dogs seem to be living in the area past an ECR of 12+/1.

How about building a 3.3 at 6.5/1 CR and reach for the same ECR as the big dogs here. This should allow us to boost to about 1.5 bar if we do it righ. Take a na motor that should make 250hp and boost it 2.5 atmospheres (1.5 bar) correctly and efficiently and that could make for about 625hp. Remember the "Monster CIS motor" thread.
Then the question boils down to getting enuff fuel into it. Porsche used MFI to get the required you all know and seen alot of threads on limits to CIS out there.
I am still amazed that these guys are claiming to run 10psi boost on normally aspirated engines....with the cast pistons and high static comp ratio they come with from the factory. How long do these last is my next question. If these are as reliable as they say then why doesn't the OEM make the motor this way from the factory? I see it all the time here in Detroit but without tearing into the engine to see for myself what else was done.....find it hard to swallow.
Most turbocharged cars coming from the OEM still run only 14psi of boost or so and they are designed as turbo engines from the beginning not normally aspirated.
1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"

Last edited by fredmeister; 04-08-2009 at 09:21 AM..
Old 04-08-2009, 09:19 AM
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