Accusump - how much PSI at pre-lube??

[Curt C.]

I am getting about 20-25 psi when pre-lubing. This is with 15/50 synthetic oil. I reach around 70 psi oil pressure / accusump pressure. Does this sound about right or do I need to pressurize the accusump more? I know 20-25 psi is just fine for pre-lube. I am just worried if it is enough to save the motor in a loss of oil pressure situation. Thanks

[Hal Copple]

i have a two quart A'sump, if i turn the motor off at about 60 psi at the engine, and about the same on the air pressure gage on the end of the A'sump, then later toggle the cold oil to "pre-lube", my Windsor motor will rise to about 20+ psi, and stay there for awhile, then slowly bleed down the pressure.

My guess is that if about half of the A'sump's oil is discharged immediately into the oil lines and the initial part of the engine's oil gallery, that would halve the oil pressure at the engine (about 25 psi) immediatly, then it bleeds down.

Mine does exactly that, so i think you are fine.

[Curt C.]

Thanks for the info Hal. Sounds like I am in the park. And, the more I think about it, upping the air charge to the Accusump would have no impact on discharge psi. No matter what the air charge is set at, the Accusump unit itself will still only achieve 70 psi - highest point of my oil pump / engine psi. Upping the air charge may affect volume though.

[Roscoe]

Mine works just about the same as Hal's. My low oil pressure warning light is set at 25 lbs and when I hit the switch to pre-oil the light will go out briefly. Takes about 20 seconds or so for it to start to drop.

Roscoe

[niles]

My does just as you describe.
By the way, increasing the initial air pressure will not increase the pressure; you will have a larger volume of air and less oil in the accu. at equilibruim.
The reason it drops to around 20 psi is that you are displacing the oil out of the accu. into the engine; the air is expanding and dropping pressure as the oil goes into the galleries until the pressures are equal(20 psi of oil on one side 20 psi of air remaining on the other side- with the piston bottomed out after full stroke). If for example, the 70 psi oil charge moves the piston to about 2in from the end of the cylinder resulting with 70 psi air on the air side of the piston. They will equalize to about 20 psi, when the piston goes full stoke, then slowly drop to zero as the oil leaks thru the bearings.
Bottom line; everything is hunkeedory

gn

[crillyiv]

I get about the same on pre-lube, 20+psi. I saw my Accusump working on video after a day at the track some time ago. Upon viewing the tape that night, I could see the oil pressure drop from about 70 to just above 40. It stayed there for maybe 1+ second and then returned to 70 when the oil returned to the sump. FWIW, this was on a somewhat long left hander with a slight bank.

Changed the pan and pump. No problems since. Still have the Accusump, just in case