Crankcase vacuum question.

[onovakind67]

Originally Posted by ZugyNA

I think the vac where the oil is picked up will be the same as it is where it can leak out of the oil galleys...i.e....the rod/mains...valve train? So any effect is canceled out? The slight vac might help the rings seal better and cause less oil to migrate past the valve/crank seals?

Vacuum is an absolute value. You can do no better than a perfect vacuum, and if there is also a perfect vacuum in the crankcase, what will cause the oil to flow through the pickup tube? The higher the vacuum gets in the crankcase, the harder it is to get oil into the pump.

[67 Satellite]

Originally Posted by onovakind67

Vacuum is an absolute value. You can do no better than a perfect vacuum, and if there is also a perfect vacuum in the crankcase, what will cause the oil to flow through the pickup tube? The higher the vacuum gets in the crankcase, the harder it is to get oil into the pump.

Back to the original intent for a minute.We're not trying to create an absolute vacuum,just a partial of say 5-10".I'm not trying to crush the oil pan with the atmosphere here,just save a little fuel. According to some dyno reports I've seen posted,there is a point of diminishing return for horsepower improvement at somewhere between 12' to 15". Beyond that increased vacuum produces no more power.