What should the ballpark oil pressure be on a 502 mpi with hot 20w-50 oil. I'm seeing about 30 at idle, and about 45-50 at wot. Does that seem to be in the ball park?

2000 fountain 27, with 225 hrs. mine is the same as yours..

That seems pretty normal for a 502.



Darrell.

Mine is all aftermarket but here is what mine is with Amsoil 15w/40. Idle is about 20 psi hot 30 psi cold, anything above idle is about 60 psi hot 70+ psi cold.

A rule of thumb is 10 pds per 1,000 RPM. I have yet to see that in most GM std. pumps though. It always bothered me with my 28 Challenger with twin 454/500 HP rebuilds. I used the stock pumps as they were practically new. I ran those engines hard for several years with the same pressure as you and never encountered any problems. It was something I would always monitor/worry when running the boat however eventually dismissed the concern.

Over the years, I've owned around 10 BBC's in various boats, some 454's some 502's, various brands of gauges and senders. To the best of my recollection, every one of them has run about 20 psi at idle (warm), 40 above 3000RPM.

I payed a little more attention to oil pressure on my mississippi run this past weekend. Especially when my oil temps were nearing 260 degrees. At wot, i was seeing about 40-42 psi. When my temps came back down to 200-220 the pressure came up a little bit more.

My 502mpi's run almost the same oil psi as yours also. After a hard WOT run, oil psi drops to 20-25. WOT is about 45psi. Cruising is about 40 psi. I run Mobil 1 15-50.

I would just like to see better than 42psi at wot when the oil is 260degrees, but that may not be feasible, may be time for an oil cooler upgrade...........