Originally Posted by
FABombjoy
Normally a journal bearing turbo should not need a restrictor. A ball bearing turbo perhaps. However on a PRV engine might be a good idea.
With a -AN4 feedline I tested cold/hot pressures at orifice sizes of .030, .045, .060. Even at .030 I measured 10psi/RPM. You won't really find any published specifications, though, other than a rule of thumb of at least 10psi/1000RPM.
You say this a lot, like in practically every turbo thread on this forum. Do you have pics of a blown piston? Have you ever pulled down and analyzed a turbo motor for the failure mode? I've only found a single photo of a damaged piston in some Legend docs. In that case it was a broken #2 ringland, but they were testing as high as 14psi (sometimes on otherwise stock engines) and the failure conditions were not explicitly stated. Suffice it to say they were learning and probably not being gentile about it.
Crankcase ventilation system is barely adequate on a stock PRV, completely lacking any sort of cross ventilation. Blowby needs to be dealt with correctly, especially when turbocharged. Both Island and BAE don't even have check valves on the PCV orifice valve. I would really love to see some bona-fide failure data.