Loewenherz Racing

#16 - Crank Case Evacuation.... Working!!

My original intent was to use a Toyota 2JZ check valve, they're positive closing and quite robust.  The idea is as each pulse passes by the Venturi in the exhaust it creates a small vacuum which the check valve allows to pass a vacuum signal into the crank case.

As the pressure swings from vacuum to positive it must shut quickly, to prevent exhaust gasses from flowing into the crank case.

The Supra valve is a great piece, but doesn't react quickly enough for this application.  Enter the replacement.

This is a piece with very low opening pressure and a light weight piston.   As a result it can react quickly enough to actually generate a solid vacuum signal in the crank case.  Vacuum is generated even at idle and gets quite strong as RPMs rise.  With the bike actually moving instead on the side stand I expect a very strong signal, at least 5 or 6 inches of mercury.  All told it was $20 for the welding, $6 for steel 3/8 brake line to make the Venturi, and $12 for the UPR check valve.

The UPR part uses delrin for the piston, aluminum housing, and steel for the spring.  Should not have any issues with chemical reactions living in this application.

Even if it only gives me 2 whp, it's a very cheap way to prevent oil leaks, keep the engine oil cleaner, and sneak in a touch more power!  All wins.