Thread: CIS Horsepower
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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Originally Posted by Thierry25 View Post
Hello Keith

The metering-cone on the 3.6T is larger than 3.3 you believe it ? So for the same air flow , the metering plate moves less !

The wur of the 3.6 T provides higher control pressure than the 3.3T...

But 3.6T injectors have much higher flow !

Conclusion: Porsche use higher flow injector for the 3.6T. In order to control these larger injector at low RPM, they increased the metering cone OD and they increased the control pressure.

Ah, another piece of the puzzle. This make a lot of sense. If the metering cone is larger, yes the metering-plate will move less. I thought the control pressure was the same pre-boost but lower on boost. However, if CP is higher that to will slow down the movement of the metering plate.

To make this work the 3.6 fuel head would have to be more like a HF and deliver more fuel at all points of the control pin's travel.

This makes the 3.6 fuel head, WUR, and metering cone viable transplants to a smaller 3.3T.

I had not thought of slowing the progression of the metering plate by making the cone larger. Makes so much sense.

I have thought of doing so by raising control pressure and clipping the metering plate or bending up an end.

I have been a long time advocate of re-profiling the cone as a way to achieve a better tuned CIS 930.

This concept opens the door for someone to come up with a CNC program to re profile the 3.3 cone. One could start with 3.6 spec or expand on this using basic interpolation as a starting point.

This would be a good match with the HF fuel head and potentially eliminate the need of a modified WUR and or RPM boost clamp.

Way, way, way cool!!!

This is a great day.
Old 11-22-2009, 04:32 PM
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