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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Apologies if you have heard this from me before.

I used the plumbing from the Andial Fueler and a Split Sec. Timing controller to make up what I called my electronic WUR. With this I did get near perfect AFR's at all points - curse or on boost. I was able to extend my gross fueling one more full point of AFR up top. Further, I was able to program in an ability to get the metering plate moving quickly with acceleration for less lag. From this I have to conclude that in theory the DWUR should be very effective and achieving its goals. It will also allow the increased flows of the IA head to be tamed. With my system, if there were to be a failure, you could just plug the WUR boost enrichment tube back in and be back to stock.

Having said that, I am back to being interested in taking a mechanical approach to extending the limits of the factory systems. If you have ever seen the AFR curves for a stock 930 that is well tuned they are actually pretty good. That is because the three systems that determing the AFR's are all ballanced to each other.

The stock fuel head, WUR, and more importantly the metering cone architecture is what determines the AFR curves. The motor was designed to make 300hp with some reserve built it. I think the fuel head can deliver about twice the stock fuel needs with adjustment. It has been done and 600fwhp has been had with CIS w/o additional injectors. Thus, I will boldly state that the fuel limit is near about 100hp per injector with approprate mods to the fuel head, WUR, and air metering systems.

Doing this is a mater of making compensating modifications to not just the fuel head but to the rate the metering plate advances (cone design or plate design) and the settings of the WUR (cruse and boost CP settings). No one seems to take a full view of these three systems and how they work together. They tweak one and maybe two and never get all three ballanced to work correctly togeather. I firmly belive it can be done.

Yes EFI is a better system and is the best way to acces power and drivability. However, at this point for me I would no sooner remove MFI from and 911RS as remove the CIS from a 930. That is just me.
Old 04-19-2009, 08:46 AM
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