[s-cars] Crank Case Pressure and Turbo Smoke?

[James Bufkin]

I don't think that it matters in this case.
What is the oil pressure relative to the crankcase pressure? (the air in 
the crank is pushing down on the oil in the pan)   The oil pressure is some 
finite amount higher than crankcase pressure.
Think about it.    Even if his crank vent system is marginally working 1 
psi would be a Tremendous amount of buildup in the crankcase.
That 1 psi is what relative to the oil pressure?   Peanuts.

His rate of leakage would have to be VERY high to build crank pressure 
higher than 1psi if his vent system is working.   Which still means his 
Vent system is more important than looking at Leakdown.  And if his 
leakdown is down around 60 on even 2 cylinders he'd notice a loss in power.

Now I agree that if his vent system isn't working then the crank pressure 
will climb very high with a corresponding increase in oil pressure, but 
then leaks should happen all over the place like the oil pan and his Oil 
Pressure should be through the roof which WOULD cause leakage at the turbo.

James

>... have you done a leak down?
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James E. Bufkin, P.E.
Bufkin Design and Engineering, inc.
2309 West 8th Street
Austin, Texas 78703
512-236-8070
fax 512-480-5927