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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,267
Originally Posted by Alan L View Post
Don't know if you are getting XS fuel dump with boost hose disconnected - but one thing you can try is splitting the boost signal to waste - or portion of. I am about to try tonight splitting mine 50/50. It is very hard to tell what signal I end up with - because depends on flow rate to boost port, but may well be less than 50%.
I think the digi WUR could compensate for your airplate - after all it is an AFR you are seeking, and the WUR will deliver that by varying CP in accord with airplate. But given the modified heads have a lot more top end fuel, there is a limit as I understand it to the CP the digi WUR can currently run to, and it is not (from memory) too far beyond the 930 specs of 60 psi.
You may need to check that, and perhaps wind your Leask WUR up to that (digi) max, and see if it is enough to control the top end dump (forgetting the leaness elsewhere - which the digi WUR will fix)
I've turned the boost CP adjustments on the bottom of the WUR all the way in as far as they go and disconnected the boost signal hose, and it was still too rich. Thats before I burned up my K27 HFS in 800 miles while trying to tune out the excess fuel dump from the modified fuel head.

When you turn Brian Leask's bottom adjustments on the WUR in all the way to raise boost CP as far as the bosch WUR can, then you have to knock the cold start CP adjustment on the top in to compensate and have CP low enough to start the car and drive it.
At that point the springs inside the WUR are almost coil bound and the WUR starts working the opposite of what you want and need... it's weird, mine would lean out the AFR on mild acceleration and richen the AFR's on deceleration when I did that.
I had to turn all the bottom adjustments back out counterclockwise around 4-5 turns and start over. I still have the bottom side boost CPR adjustment knocked inward almost all the way because the modified fuel head's AFR's were so rich it wouldn't even run when you put your foot in it.

I want to find a stock euro fuel head and sell the modified head to someone who's racing a 930.
Maybe insane cams timed late like around 1mm, huge ports, race gas and 1.5bar are what you need to run some of the newer modified fuel heads.
There are some guys here with older modified fuel heads that they say are giving correct AFR's with the rpm activated solenoid set to around 5000rpm in the boost line, and a similar engine configuration as mine.
Old 10-31-2008, 03:57 PM
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