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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Originally Posted by zcoker View Post
There must be something to this CIS system that we are missing because this is directly in-line with the 'CIS Monster thread that I started whereat that guy is getting over 600hp out of CIS. I don't claim to know this system a whole lot like I do EFI. Just how much fuel can a CIS system put out?
I think he has found the limit with out major changes like drilling out the two other blanks on the fuel head for more flow. For all I know, he may have even done that. I think Porsche took that approach with one of there 924 race cars.

He also knows how to build a motor that will not lift and leak at the heads, that will stay together, and breaths very well. He also has a very efficient turbo.

His biggest trick is he is managing boost much differently that we are and goes much higher than 1 bar in the mid range. I believe he keeps pushing boost until he reaches the total fuel deliver capacity of the fuel head. Then, when the motor can not push anymore fuel, he starts pulling boost back fitting the boot level to the fuel deliver limit to achieve stable AFR's to red line.

His peak TQ is artificial and where he first starts to manage and reduce his boost level. His peak HP is where his motor is at its peak VE which is the same place we hit our peak HP. I bet he is pushing somthing around 1.5 bar in the mid range. That is just over 22 lbs. Many run boost into the 30's.

With our motors, our TQ curve is steep until we reach our target boost level. Then the TQ curve takes a turn as we hold our boot goal and we try to hold this to red line. This puts our TQ and HP at there natural points much as if our motors were normal aspirated.

He seems to be using a stock set of euro heat exchangers and probably a turbo with a bigger compressor wheel than we are even with the larger HF's.

This is repeatable with some effort but buget for rebuilds based on hours instead of miles if you track it.

I made some posts near the end of that thread.

Old 03-06-2009, 04:26 PM
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