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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Originally Posted by JBL930 View Post

When i had these two new hybrid K16/24's installed on my 993 lump

I set off for Le Mans 2008, i got nearly 2 miles down the road and the new BOV'S i'd had fitted

Failed! What happened next was strange. The BOV's were second hand, they didn't open on vacuum. The right hand turbo stalled, the nut then came off the end of the shaft on the compressor side and the left hand turbo sucked it all the way around the back of the intake and into the compressor of the LH turbo, Basically destroying both turbos. Not a good day!
Stock Porsche BOV's in now and all is well, RS Tuning use the stock 993tt BOV's in even their most extreme road turbo builds.
Lesson being, use proper BOV's
Everyone else installs there BOV or CBV with the piston perpendicular to the boost pressure. This is the right way to do it but the boost side loads the pistons.

I ran mine so the position pushes against the boost and in the same line. It took a the spring tension to a small degree and the boost building up behind the piston that had about three times as much surface area to push the valve closed.

Again, my valve stayed open most of the time to keep the turbo spinning. Not like they are supposed to be run. Any time there was vacuum pulling in the intake manifold, they it was open. Like at idle and cruse. Accelerate, and they snapped shut.

Never though about it till now, but I can understand why your BOV may have failed with all the side loading. My set up would likely have kept that from happening and given you faster boost.
Old 03-07-2009, 05:55 PM
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