Originally Posted by
John_M_
Thats basically what OS did with their EFi system, and they used the remote needle valve to set the bias pressure.
Thats the issue with crankcase blowby, especially with 4 strokes decreasing with rpm... and with OS's EFi system, you had to adjust the tank pressure to optimize the performance... and that was never a constant either... the raise and fall of tank pressure that follows rpm / exhaust pressure has always worked well, and trying to artificially recreate that can be done, but to what level of accuracy, and reliability... the more ancillary equipment you add, the more it affects the serve life, and reliability... but Isolating the contaminates in the exhaust pressure feedback to the tank, would be an improvement though, get rid of the crap trap.
Nope... In a good functioning engine with a good liner and ring condition, my tests have shown that blowby is near zero at full load, and remains near zero all the way down to a certain RPM (in my test engine, the 91 ASP fourstroke that RPM was between 3500 and 4000) where it suddenly strongly increases and then also remains more or less constant.
I believe this to be the combustion pressure forcing the ring to seal up against the liner above certain loads/RPMs, and I have no idea if every engine responds the same, but I DO know by logical deduction that ingestion of dirt WILL disturb the parameters of this behaviour..