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TurboKraft TurboKraft is offline
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Join Date: Mar 2005
Location: Phoenix, AZ
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Originally Posted by 935K3 View Post
I'm assuming that includes the Megasquirt ?
I'm building a retro 934 from my 930. The 934 used CIS but it had a custom outlet plenum almost direct downdraft to the turbo compressor inlet, the metering plate was replaced with a aluminum cone, info I have states that system had twice the airflow of the production unit. Interestingly the factory 934 manual shows the original car didn't even have a WUR just a manual adjustable fuel pressure regulator.
They did flow more, yes, and had relatively flat fuel curves thanks to a combination of
a. the airflow meter
b. the FD+WUR

I would not be surprised if some had no WUR because they really didn't operate under a wide range of conditions, just one: flat-out. Racing. Easy to tune fuel for WOT only when you don't have to factor in cold start, low speed / part throttle, etc.
We have had race 930s in the shop with a simple adjustable pressure regulator, or no manifold referencing. It works for power, just not optimal for all driving condtitions.

Originally Posted by 935K3 View Post
Question: higher the rail pressure = lower fuel flow at fuel head ? Did get that right, the opposite of what you would think ?
Higher control pressure = less fuel out injectors.

Originally Posted by 935K3 View Post
Later picture I have seen a 934 with a WUR mounted on the side of the 934 outlet plenum
My plan so I could hopefully run the car in 934 eligible events was not to modify the fuel flow, just fab the outlet plenum, the "ally metering cone " is available from Germany, then run a hidden EFI system on top, I know it will take a lot of work to get the fueling correct so I would need the CIS to be at a low fuel flow rate that is stable across the rev range and temps so I could rely on the EFI system
We have two of those metering systems in stock, happy to help you out.

If you're competing in something like the Youngtimer series, the EFI is prohibited. They are much more strict about following the rules, not just the letter of the law but the spirit as well (ex: even though period-correct parts, no RSR ITBs on your 934-tribute car).
Chris Carroll
TurboKraft, Inc.
Tel. 480.969.0911
email: -
Old 01-05-2016, 10:03 AM
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