Thread: K27 7200 or s
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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
The 7006 was Porsche's go to turbo for there special 1992 S2 Turbo that was based a 92 C2 Turbo with cams, bigger inter-cooler. This was offered to qualify the turbo for I thin IMSA racing back then. It was $10k option installed by Andial for the factory.

It is interesting in that the compressor wheel is just a touch smaller than the 7200's so you would think it would be a lesser turbo.

However, they made the hot side larger which put off boost for about 300rpm and lowered back pressure in the exhaust system. This made the motor run more efficiently and thus made more some +20 or so HP in the power band. I wish I knew if it was a larger hot wheel or more of a larger housing.

I think the K29's and RUF turbos might have been built on a 7006's hot side but w a larger compressor wheel. That would increase the efficiency in the exhaust and the efficiency on the intake side. The K29 was another early Hybrid I suspect and it was the go to turbo for getting to 400hp or so. They would get to full boost came in by at about 3600 rpm compaired to about 3200rpm w a 7200 if I recall correctly. Of cource set up move this around.

I have seen a 7200 reach .8 bar before 3000rpm on a well set up car.

If I build another 930 it will be more for DE's and I will look to somthing more like a K29 or HF based on a 7006 hot side if possable. Or I might just try going with a GT35 style turbo.

I suspect of the issues w a 930 is the restriction before the turbo from the metering system. Turbos just do not like any restriction before the impeller or after the turbine. I suspect putting larger compressor wheels exadurate this issue at lower rpm and work against response. A larger compressor dose increase effecency once up to steam. It also moves air a bit quicker but it has to work against the hot side to do so. This makes for a bit earlyer boost onset ad a bit later full boost which makes it come in in a more progressive manner.

Sorry for the rambelings. Just what I belive so far. The cool thing is we have a lot of options now.
Old 12-11-2009, 08:21 AM
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