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JakobM JakobM is offline
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Join Date: Sep 2010
Posts: 307
Yes, cover plate = bolt-up flange with no hole to completely disable the WG

Leak test: Normally on 4 cylinders all inlet valves are closed when engine is parked, so pressure is applied all the way from cap to inlet valves with throttle body open. Here we look for 1psi leak/sec when pressure test over inlet valves @ 12 psi as some air will leak down the valve guides.
With our 6 cylinders porsche at least one valve are open when parked, so yes start making the leak test up to the throttle body keeping it closed. Make sure to start low at maybe 6 psi, then step up. Best is to use the same nozzle in the cap as used for car tires as these have restrictions in them so you wont shoot 8 bar in the system
You need to borrow or buy that air compressor to do these tests best

You have a 0.5 bar spring. That is a SOFT spring right there in a 46mm wg. Try to put pressure under the WG membrane and see when it start open - my guess is as early as 0.2 or 0.3 bar and fully open at 0.5 bar with your 3 port solenoid valve. Meaning easily pressed open by back pressure when start building low boost in your engine. AND you have a large 46mm WG so alot of surface area to push back that tiny 0.5 bar spring. Do the test on the table and you get to know what spring(s) to put in. If the membrane diameter is same as 46mm then your reading will be equal to backpressure, if membrane diameter is smaller then back pressure has even more force than the pressure you apply under the membrane. When doing the WG pressure test on the table a regular football- or bicycle pump is just-as-good tool for the job. You need a line of rubber hose, a T-joint, and a pressure gauge. So easy start there

When picking the right spring, for your target boost of 1 bar, I would start test on the bench with a 1 bar spring as many of the springs starts open WAY before advertised. As mentioned above in my first post, we had to put two springs in a tial 38mm wg with total advertised 1.8 bar when in fact these two together only had the valve closed uptil 0.8 bar applied pressure under membrane. My advise buy some inner smaller diameter low spring rates you can combine with your existing 0.5 spring or 0.8 or 1 bar spring. You will be surprised how much earlier the wg valve open compared to spring rates.

I am not sure I understand what you are aiming for with the 0.3 bar (130kpa absolute) in your programming. What is the thought behind? I would say, make sure - and test! - that your boost solenoid is not letting go of the top port on the WG too soon before you reached your target boost of 1 bar (200 kpa absolute). Otherwise this will add to the back-pressure force and be part of the reason for the WG will not close for boost buildup.

The quickest test for you is to take a run with the pressure hose on top of your wg only - and your 3 port solenoid disabled left home, and see if this make a difference. Best of course to use the cover plate / bolt-up flange and get it all "zero'ed out"
Old 07-21-2019, 04:43 AM
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