Oil Pumps/Oil Pressure

Old 11-02-2007, 04:32 PM
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Join Date: Aug 2007
Location: Bedford, Ohio
Posts: 86
Default Oil Pumps/Oil Pressure

Have a general question about an argument that was put to me. The argument was that for every 1,000 rpm, you should have 10psi plus 10 psi cushion.
But I've never blew an engine I've built (or any period, yet) and never gave much thought to how much oil psi vs rpm. I've always replaced the oil pump with a good brand high volume oil pump when I've rebuilt or built. I have had the machine shop add some oil porting.
Have I just been lucky? Guess I'm looking for some advice here, I'm currently builing a couple of motors to run to 8k. Ed, George?
davebat is offline  
Old 11-02-2007, 05:45 PM
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Join Date: Oct 2004
Location: Newport News, VA
Posts: 139

Ed can give you the whys and wherefores better than I can. I do the 10 psi per 1000 rpms without the added 10 psi cushion. But I just build motors for myself so I'm the only customer I have to satisfy although I am more picky than most.

I think the trend today is to go with tighter clearances and less oil pressure but I am old school enough that if my rod clearances fall between .0025 and .003 and mains between .003 and .0035 then I'm happy running VR1 20W50 at the 10 psi per 1000 rule. Having said that, I know guys running a lot less pressure and spinning their motors 1000+ more rpm than I am. I just feel the extra pressure and wider clearances gives a little more cushsion when things don't go right like mild detonation. But there's a price to pay. You have to have enough volume to get the pressure up and that means 6 quarts of oil may not do the job under all conditions and then there's windage to think about as well as the horsepower it takes to turn the oil pump. In a bracket motor that's not as important as in the heads up classes. Some of those guys will run a lot less oil in the pan to keep the windage down and run tighter clearances to decrease the volume of oil needed.

But for me the old 10/1000 works fine.

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