Thread: K27 vs K28...
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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 squerly View Post
Thanks everyone for your input. How would I know if my current turbo is a HF? Can you tell by looking at it???

I would have to go out and drive it to be sure but Iím thinking that it starts noticeable spool somewhere around 2500rpm. Also... there has been reference made to the "cool" side of the IC. Which side is that??? (Sorry my knowledge base is very limited. but I'm working on it...) The weather isn't too bad today so maybe I'll drive it to work and get a accurate spool point.
This is a very complicated science and I don't have enough experience to tell what you have from the pictures. IIRC my HF differed from the stock K27 on the cold side. It had double the number of blades something like 16 vs 8.

The cold side is the cast aluminum side with the non flanged opening. This is what pumps cold air into the intake. The hot side has the flange and is attached to the exhaust. Based on my charts and experience my HF K27 begins to spool quite early. I am at 4.0 PSI at 2000 rpms and at 14.5 psi at 3200. There is a slight creep up to 14.8PSI at 6000 rpms and drops by .1 PSI at 6500 rpms. This is running B&B headers which help reduce the lag and stock cat which help create the lag. I plan on going with a 100 cell cat which should reduce the lag considerably and have me up to full boost by 3000 rpms or sooner. If this were a stock K27 you would see boost falling off at around 5000 rpms and if it were aK28 or K29 you would see a much later spool up and be equally as strong up to redline.

The older design K28/K29 turbos were good for high powered track cars but did not help with low rpm driving. For street use any of the newer K27' hybrids are much more street oriented and offer better overall control with equal power up top. I would contact Stephen from Imagine Auto, he is quite knowledgeable and can set you up to accommodate your specific needs.
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Old 09-28-2007, 04:51 AM
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