Discussion
It depends on so many things, oil pump, clearances (built in or worn in), oil etc. I have 4 bar and 1 bar at idle (dry sump SBC 427, with 20-50W). Rule of thumb I was taught was aim for 10 psi for every 100 HP at WOT.
Too much is also a bad thing, I've known engines that wouldn't rev past 4500 rpm because of too much oil pressure, especially with a hydraulic lifter cam.
Too much is also a bad thing, I've known engines that wouldn't rev past 4500 rpm because of too much oil pressure, especially with a hydraulic lifter cam.
A lot depends on the accuracy of the gauge ! I have a standard guage on a flexible nylon pipe. To calibrate/ check my other gauges .
My pressures are .
COLD HOT
1000 rpm 80 psi 1000 rpm 55 psi
4000 rpm 110 psi 4000 rpm 90 psi
If you have Chevy engine there may be one or two pressure relief valves , both adjustable DIY fashion .
The pressure does not neccesarily indicate the state of the engine wear . I've had knoking big end bearings and rumbling mains with no drop in oil pressure . If the pump is big enough it will maintain pressure but the relief valves will be closed up .
Frank
My pressures are .
COLD HOT
1000 rpm 80 psi 1000 rpm 55 psi
4000 rpm 110 psi 4000 rpm 90 psi
If you have Chevy engine there may be one or two pressure relief valves , both adjustable DIY fashion .
The pressure does not neccesarily indicate the state of the engine wear . I've had knoking big end bearings and rumbling mains with no drop in oil pressure . If the pump is big enough it will maintain pressure but the relief valves will be closed up .
Frank
If Frank's engine is half as good as his body fit then 90-110psi sounds quite appropriate.
So long as the relief valve is working and its dry then there isn't really a problem.
Contrary to what Mr Vizard has written I personally think a high performance, 'endurance' pushrod-motor, lives much longer with 'lots' of oil around the top-end.
If you are building drag-race engines which might only cover 200miles between re-builds then Dave Vizard's dry top end method is probably the way to go for that last 5-10hp.
Oil is your 'friend' for a more consistent, reliable Ultima installation.
So long as the relief valve is working and its dry then there isn't really a problem.
Contrary to what Mr Vizard has written I personally think a high performance, 'endurance' pushrod-motor, lives much longer with 'lots' of oil around the top-end.
If you are building drag-race engines which might only cover 200miles between re-builds then Dave Vizard's dry top end method is probably the way to go for that last 5-10hp.
Oil is your 'friend' for a more consistent, reliable Ultima installation.
Edited by 738 driver on Saturday 9th May 21:09
I reported said oil pressure to Gail at AS who said it was on the high side but not to worry . It has hydraulic lifters and revs OK .If anyone can see any danger in my high figures I would like to know . I am not frightened by high oil pressure . I used to rebuild Aston 6 cylinder engines .When they tested the engines on the M1[in preperation for Le Mans !!!! before the speed limits ] the big ends used to fail due to expansion of the aluminium block and loosing pressure through the main bearings . They changed to an enormous chain driven oil pump and relief valve ,and final assembly of the main bearings was done by colour coded shells varying by .00025 " to obtain .00175 "running clearance . The pressure gauges went up to 180 psi and an engine would commonly run hot at 120 psi . The 2 DB4GT's I owned had 12 plug heads and twin distributors . They were 3.7 litre and had 325 bhp . Not bad for 1959 ! I would often strip engines with good oil pressure as a precaution to find all the shells down to their backing . That would be after say 60,000 miles .
Frank
Frank
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