Atpsr22

Ok oil gods!

Bought a used HP500 from a reputable place, compression and leak down were all within spec. 270 hours on the motor, 70 hours on a fresh top end. Currently running 20w50 dino oil and a wix Racing filter. Oil pressure is 58-62 psi idle start up cold, 49-55 psi Turning 5k rpm’s (hot.) 40-45 psi turning 3500 rpms. After a moderate or hard run the pressure at idle will drop to 12-14 psi(in gear 750-800 rpm). After a couple of minutes will rebound to 18-20 psi. Bump the throttle to 1000-1200 rpm and then pressure will be 25 psi or so. All confirmed on a mechanical gauge. Is this normal or should I be concerned. Didn’t see any metal in the last filter. But it only had a handful of hours on it.
Thoughts and guidance appreciated!
I should note I do not have a oil temp gauge... I know I know it’s the next purchase....

Smitty275

Perfectly normal for a performance engine to be that way. Not unusual at all.

Griff

That is pretty normal.

Baja Rooster

iTrader: (1)

Perfectly normal. Your heart sinks the first time or two it happens but it’s common after even a mild flogging.

Fwiw, I oversized my oil cooler using a thermostat and it minimized that dramatic swing a good deal.

TomZ

iTrader: (2)

I saw the same with my 502s with factory oil cooling and just about had a heart attack when they dropped to 20 lbs. Doing just as you described showed the same results, and when I did a tear-down on both this past fall, the bearings were in great shape. The rebuilds have huge coolers and I’m using high volume pumps so this should be minimized.

On my buddy’s Cig Bullet, 454s and blowers, the oil pressure hardly drops at all even after beating the snot out of it so I was really surprised when my stock 502s lost so much pressure. His set-up... no thermostats and huge oil coolers.

1MOSES1

those numbers all match our 500efi...+\- a few psi

Atpsr22

Thank you all for the input!

jeff32

Might try 25/50
but harder to find than years ago, in my area at least!