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Old 03-03-2012, 07:12 PM   #12 (permalink)
3-Wheeler
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Quote:
Originally Posted by oil pan 4 View Post
A high vacuum would be bad. Having about -5psi or 10''Hg is ideal....
You would have to ensure that the rubber crankshaft seals and such would actually withstand such a high differential pressure, between the vacuum in the crankcase and the outside world.

I doubt that normal lipped rubber crankshaft seals would withstand such high vacuum.

More modern seals have very low lip strength, to allow less rotating friction, and would only handle about 1 inchHg vacuum before the seal starts to fail because of the thinness of the rubber.

Jim.
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