PCV, advantage or not?

[Bub Whitaker]

Originally Posted by Bill Harris

I know of someone who tried the two PCV deal, no breathers, etc on an engine on the dyno and lost serious power. The idea is that the PCV valves would make a poor-man's pan-evac, pulling a vacuum on the crankcase. Problem is that like it has been stated, PCV valve(s) is closed at WOT so the idea falls apart. Pressure builds in the crankcase and you lose power.

I have run with and without a single PCV with a breather on the opposite cover back to back. It made no difference except that I get less oil blowing out the dipstick tube when there are two open breathers than when there is one with the PCV. The pressure has to go somewhere, and no matter how well sealed the motor is, there is going to be blow-by.

Poor-mans pan evac, exactley! If you lost serious power on the dyno, and your blowing oil out the dipstick tube, then you need to work on your ring seal. Serious blowby unloads the top ring and blows oil out the dipstick, causing loss of power. This is one way you guys can check to see if your rings are sealing. A good ring seal will pick up with the "poor mans pan evac"