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copbait73 copbait73 is offline
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Join Date: Nov 2003
Location: Chesterfield IN
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Originally Posted by mark houghton View Post
What's a vacuum driven WUR? Yeah, there's a "vacuum line" attached to it, but it has nothing to do with vacuum and everything to do with transmitting a boost signal to the WUR to enrichen during boost.
Am I missing some cool mod here or is it just my narrow minded 930 view of things?
This is a naturally aspirated motor, the WUR only senses vac. Your 930 WUR has a pressure (Boost) one side vac the other (off boost). Everything is cool with N.A. (vac only) WURs up to the point manifold pressure changes to positive.

I protect the WUR vac line with a check valve. This makes the WUR see Boost as the same as full throttle. Problem is the system runs out of additional fuel and goes lean over 5000rpm without supplemental fuel being added. I use a 7th injector with split second controller and program in additional fuel.

I experimented with 930 WURs (pressure/vac) and they did not work on my smaller motor. One may be the answer to this 3.0L conversion however N.A. conversions have been done for years and all that I know of have used supplemental fueling.

The delay problem sounds like an exhaust leak - (flange alignments/gaskets) or

A lazy wastegate - the W/G having a low pressure spring desired for low boost may not be strong enough to hold the valve seated against the exhaust pressure. Pulsation can blow it off the seat early. I would lock down the W/G (disconnect and run the adjustment screw in) and do a road test using the boost gage to see it this is an issue. Controlling to low manifold boost pressure is often more difficult than controlling to a high pressure.
Old 09-03-2011, 07:10 AM
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