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Cobalt Cobalt is offline
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Join Date: May 2004
Location: New Jersey
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Originally Posted by 911st View Post
K27-7200 is very well fitted to most 3.3 turbos. Comes in hard and fast but runs out of HP a little above 360hp. Is was used by Porsche on the C2 3.3 and 3.6 turbos. It was basically at its limit with the 3.6. It is a great fit for the natural fueling capacity of a non modified CIS fuel head and WUR.

K27-7006 basically had the same size compressor wheel as the K27-7200 but had a larger hot side. It was used on the S2 which a special option 3.3 C2 turbo that was built by Andial to qualify the model for a race series. Other mods included C2 normal cams, and a larger core welded into the inter-cooler. What the turbo did mostly was reduce the back pressure in the exhaust system and was a better fit for a track duty 3.3 running reasionable boost pressures.

The K27 HF basically uses the small hot side from a K27-7200 but adds a large compressor wheel. This makes for earlier boost onset but with the large compressor wheel fighting the small turbine, it takes longer duration to reach full boost than a K 27-7200. It still may reach full boost at the same time, just takes longer from start to finish. It kind of makes the Turbo feel more like a normally aspirated car but with more power. With the larger compressor wheel the compressed air dose not get as hot and boost dose not fall off at higher rpms. One of the concerns with this turbo is it pushes the relationship between the compressor wheel and hot wheel to an extreme. This makes for a lot of exhaust having to now exit the Wast Gate. Some cars just do not have adequate WG circuits and this can make for an over-boost situation. Just something to watch for.

I defer to the experts.
Are you sure the 7006 was used on the S2's? I was under the impression that the turbo remained the same as the stock unit used on all the 964 turbos. the 7006 was fitted to the 94 turbo S's. I swapped out my 7200 on my 3.6 with a HF K27. Dyno charts show that it not only starts to build boost lower it reaches full boost (plateau) at lower rpms than the stock 7200. The HF does creep a little but not bad and as you can see the stock K27 loose wind early. the difference in the compressor wheel is not overall size as much as added veins. In addition to the 12 primary veins there are 12 secondary (or veins beneath the veins). hard to explain without a picture. I have some older charts of a stock K27-7200 vs a HF K27 at 2 different spring rates. Not sure if this helps. I do prefer the power delivery and improved throttle control of the HF over the stock K27-7200.
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Last edited by Cobalt; 12-17-2009 at 12:59 PM..
Old 12-17-2009, 12:45 PM
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