I have 236 Eagle eliminator. With a 502mpi Merc cruiser. The longest I have it at WOT it's about two minutes. Probably cause I don't know how to drive 2 to 3 foot waves. I have driven 3/4 throttle for about 45 minutes. Oil pressure runs 65lbs. But it went down to 30 pounds so it lost 35lbs pounds. Is this normal. Mobile one 1030. I since have changed to mobile 1 15/50. Not sure if it changed. I was using a little oil but it stoped with the 15/50. Temp stays at 180. What is your longest WOT? And oil pressure? Boat at WOT is 72mph. Boat seems like it starts to get a little flighty at top speed as well. Maybe trim tabs would help I don't know. Thanks for your input. Gary

Mine runs about 60lbs at first start, once warmed up it settles down to about 45lbs, and WOT its right around 65lbs. Is it 30lbs at WOT or idle? 30lbs WOT you have an issue, I believe you need atleast 7lbs per 1,000rpm's. But regardless if you have always been at 65lbs and now you are at 30lbs something happened

You shouldn't be running 10-30 IMO. I believe the 502mpi merc recommends 20-40 and the 10-30 won't handle the abuse of wot runs for extended periods. Others run 20/50 conventional oil in their 502mpis. Do you have an oil temp gauge? If you're losing that kind of pressure something is up. Viscosity could be an issue and/or oil temp is getting way hot. I would investigate the oil tempature thing before you run the boat hard again. That low of oil pressure would prob do some damage on the main bearings but I'm no engine expert. I believe the rule of thumb is 10lbs per 1,000 rpm minimum. For what it's worth I have ran wot or pretty close to it for 35 miles and it was steady at 65-70 lbs all day.

The first place an chevy will loose oil pressure is the cam bearings, then from there it will wear out the rod and mains.
A BBC should be at min 20lbs hot at idle, the top side depends on your bearing wear and oil pump, oil etc.
If you are loosing half or more, you have wear.

Also, concur on the 10-30.

Now, the being honest about WOT. I tried it once for about a minute. It scared me so bad at going over 42 that I had to let off....

try running a 510 inch Supercat 750 at 7400 for forty minutes straight . . . . always made me nervous but they stayed together (most of the time lol).


In SCL, SVL and SV they would run 525EFI's for hours on end at WOT with no prob, they can take it. Your marine performance engine spends its life in a full dyno pull. I had to kind of laugh a bit when GM had that ad campaign going for the 572 Performance Parts crate motor where they claimed to stick one on a dyno and go home for the night. No biggie there why shouldn't it survive, thats like fifteen hours of normal boating

Just measured the actual pressure with a manual gauge and it reads 68lbs at idle. I changed the sending unit and it also shows 68 at idle. So the sending unit that was in the motor was way off. So now I just have wait and see when I run it in the water. Oil pressure is steady at 68 -70 pounds idling now at running temp. Now the oil question. I was reading that M1 is now a SM OIL whatever that means and that offshore engines, need oil with ZDDP. So now I am confused.

Hi Folks

I can't compete with you big dogs - only have a stock 7.4 mpi and WOT for me is 63 mph. I did it a couple of time and to be honest, it scared the heck out of me. You eat a lot of real estate up real quick and most of the time you don't know what idiot in a ski-do or other boat is going to zoom out in front of you. I have the most fun and feel in control around 40 mph mark.

Let's all be safe

3pointstar

I have run wfo for 15min longest to date was nervous but it stayed together oil temp was 190 and pressure was 70psi after the run don't know if I would do it again be a use the next stop was the gas dock....

Could be a lot of things.

Oil could be whipped out - Should be running 20/50 at the least 20/40
Oil could be suspended (add more oil)
Gauge could be malfunctioning

Know what u mean. It's like what the hell did I just do?