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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Quote:
Originally Posted by Cobalt View Post
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.
A K27-7200 is just not a very good turbo for a 94 3.6T. It is very near its limit on that car.

An HF on a 3.6T I would expect would be a wonderfull up grade and should be able to reach .8 bar boost before 3k depending on exhaust.

As to the special 3.6 Turbo S, there has not been any discosure of what the actual turbo was that I could find.

There has been descriptions as to how said car responds. From discription it is a little laggy or mabe just such low HP it seemed so. But it run like crazy up top. My guess it was a special build and probably was simmiler to an HF built on a 7006, an old school K29, or RUF turbo. I dought they would put the small hot side from the 7200 on it. It might just be somthing like a #13 hot side.

From the info I have seen on tuning the normal 3.6 the 7200 runs out of air flow when performance is expanded even just a little and it just overworked by 400hp.

The 3.6 is a different animal than the 930. It has higher compression and is a biger motor so it moves a lot more air faster than a 3.3. I suspect Porsche took kind of a short cut putting the 7200 on it but that is what they had.

If I was tuning a 3.6 I would want a larger compressor wheel like a K29 or HF but I would also want the effecenty and HP that can come with a larger hot side of a 7006 or such. I would improve my low end in other ways.

From my limited experance putting a larger compressor wheel in a 7200 like an HF or quick spool K29, boost onset starts earlyer. I belive it dose so because the compressor wheel moves more air with each revoluition. However, this also pushes back agaist the turbine wheel. Full boost might come in close to a 7200. However the time from boost onset to full boost is longer and more controled. The 7200 reacts faster from boost onset to full boost. and on a 3.3 can come in earler. I just like how hard a 7200 comes on.

As to the S2 I am very sure it had the K27-7006. I am not sure if they opened up the intake ports. I tought it had C2 normal cams but others seem to belive it was and SC so I am also less sure about that.

Again, what is cool about the 7006 is it actually has just a little smaller compressor side than the stock 7200. Not larger like one would think. However, the larger hot side alows for lower back pressure and increase effecency. The result being and expanded level of gross HP.

I wish someone would test the level of back pressure that builds up in the exhaust with a 7200 and a K29 quick spool or HF. I think on most turbos the pressure in the exhaust is almost 3 times boost. I bet there is a mesureable and maybe signifficant differance. Great for a street car but mayby not the best choice for a track car.

It is interesting but there is HP hiding on both the hot and cold side of a turbo.

At least this is what I belive but I could be wrong.
Old 12-17-2009, 02:11 PM
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