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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
In 1991 Porsche came up with the K27-7200 for there new C2 Turbos. This is a great fit on a 3.3 CIS motor up to about 400chp. Its small hot side makes them come on early but the smallish hot side chokes near the same HP level where a stock CIS without fueling mods starts to go lean.

I suspect this was done on purpose as a small protection limit but I could be wrong.

However, for Porsche's special higher HP cars like the 1992 S2 or 3.6 flat nose options they fitted the 7006. It was Porsche's go to HP turbo.

I believe it mostly had a larger hot side for less exhaust reversion and it dose not choke and limit compressor speed / boost delivery at upper rpm's. It is reported to make maybe another 20-30hp. As noted it comes on boost about 300rpm later but it dose so with authority.

The aftermarket built HF's usually keep the small K27-7200 hot side and fit a larger compressor that can move more air before the hot side's choke point. The compressor wheel is also more efficient at higher HP levels. Boost onset seems to be earlier. However it tends to build boost over a longer rpm range in a more liner manner than the 7200 and 7006.

To me the main difference between an HF and a K29 is the HF and the K29 had larger compressor wheels. However the K29 also had a larger hot side.

All good turbos and well suited to 930's depending on one's goals. However some believe there are newer better turbos (GT's) out there if one is willing to work a bit to fit them. But the K27 based turbos are believed to be more reliable on air cooled turbos.

Just my opinion.
Old 09-10-2010, 08:28 AM
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