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Old 03-17-2009, 08:53 AM
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Effects of too high oil pressure ?

Been reading some posts regarding oil pressure and effects of oil viscosity, use of HV oil pump and increased oil capacity. My question is what effects of too high of an oil pressure would be on an engine (specifically a SBC) ? Would it be possible to force oil past rings and seals like similar to the effects of too much crankcase pressurization ? I have been told that an increase in oil pressure can increase the windage effect caused by excess oil from the bearings. This in turn can put so much oil on the cylinder walls that the rings are unable to handle it, thus causing blow-by. Is this accurate ?

Right now I am running 10W40 and was going to try 20W50. I have a 7qt oil pan + filter, HV oil pump on a SBC 383 stroker. I did temporarily run an electric sunpro oil pressure gauge and I seen numbers of 75psi at idle and 85+psi under load. Dropped around 10psi or little more when engine reached operating temp of 180F.

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Old 03-17-2009, 09:05 AM
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Your hot oil pressure isn't excessive, especially if this is a fresh engine. You might be getting some oil bypassing the filter if so equipped. I like to block the filter mount's bypass off w/a pipe plug.

You're not bulging the oil filter at cold start-up, are you?
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Old 03-17-2009, 11:48 AM
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The big thing about too much pressure is exploding oil filters. Otherwise, pressure that is too high might suggest oil that is too thick which can cause excessive cold start wear. That cold start pressure is awfully high. At those pressures, the bypass is fully opened, no oil is getting filtered, and its probably about like molasses. 10w30 in most of my chevy builds puts me at about 60 psi cold startup, then 20 hot idle and 60-70 hot redline.

More isn't better. Correct is better. Your 10w40 pressure numbers look great, in fact a little high at cold temps. Going to 20w50 would definitely be a move in the wrong direction. Slight loss of power, definite loss of lubrication protection, potential for exploding your oil filter.
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Old 03-17-2009, 12:39 PM
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Agree with Curtis. Would go to a thinner multi-grade oil such as 5W-20 until the bearings clearance themselves.
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Old 03-19-2009, 01:13 PM
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Thanks everyone for the tips. I will revert back to a thinner grade oil. I was just hoping the heavier weight would "help" with my other issue of possibly needing a re-ring. Now suspect rear main (2pc) or rear of oil pan is leaking under load and making mess and difficulty to track oil consumption. I guess a re-ring and gaskets is in order. I just have a bad feeling that there is something complex going on (factor of few things not one). For example just fixed PCV system (missing breather). All the local performance machine shops have differing opinions, for example talking about head change, cam change and carb swap. Already have $$$ in this build which is all new parts and only 700 miles.
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