I have a 454 Mag MPI with a procharger. Bought the boat and was told motor was fresh . About 40 hrs the oil pressure started to fluctuate. When Cold oil pressure runs 40 at idle then 55-60 at 4000 rpm. If I do a long wide open run about 3 min oil temp rises to 220 f and oil pressure drops. It will idle at 15 ibs and at W-O run 30 to 35 ibs. I have changed out the sendor to a mechanial guage same results. . I have no oil leaks and compression check shows 150 psi across entire engine. My question is if I pull the motor and find out the bearing tolerance is the issue can I just redue the crank if every thing else is OK . Local engine builder only wants to do it if I agree to rebuild everything. Could it be my oil Pump also ? I am also in process of remapping the mefi with a A/F as my fear the current set up is way to rich . I am going to get the map correct then change the oil and see if its gas in the oil due to rich condition .

Did you replace the filter?

If the oil temp is getting too high in a boosted application, more than likely your AF is going lean at full throttle. Put an oxygen sensor in and go for a run and see where you are at.

Also if you are using the sea pump to supply the intercooler with water, you need to stop that and go to an offshore pickup. Why take cooling water away from the motor ???

Also 3 minutes at true FULL throttle IMO is running any motor too hard.

I've seen the same problem in one of my hot rods, it ended up being the oil I was using. Changed to different brand problem went away. Try a high Zinc synthetic like Amsoil Dominator and see if you still have the same problem.

Isn't that why the linkage goes there. My last boat and this one I've left it at full throttle for 20 minutes plus. Sure, a couple breaks for waves and turns, but WFO basically.

Replaced Oil Filter tried new oil high Zinq 20-50 . Only thing I have not replaced is the pressure relif valve on the block. Boat is running 11.5 AF on the guage at wide open !! so im not lean .
THX for the comments

There has to be a reason why your bearings went bad so soon. If you don't fix the problem, it will just happen again. Lets say the motor was rebuilt but assembled with improper tolerences or it was not properly cleaned before assembly. A scored crank will require a complete dissasembly. Checking clearences properly requires pulling the crank and rods to check main and rod bore sizes. It may not require a complete rebuild but i would disassemble and check everything and at the least hone and put a new set of rings in it.

Oil pumps almost never go bad unless a piece of metal goes through it. Some times the pickup falls off but then the oil pressure goes to nothing. 220 degrees is normal operating temp. Pressure should not fall off at this temp. When I was having oil temp problems, my pressure was 65lbs at 280 degress at 4000 rpm.

pull the oil filter and cut it open with a set of tim snips..look at the inside of the filter for babbit and brass shavings..if their are none then youare ok for the moment..figure you have another 150 hp from the pro charger..loke smitty said get a ;wp and run your cooler through it..will get more hp and the boats injectors wont puddle at idle..your also going to have to up sive the oil cooled..get the one that mounts on the rear bell housing..3x21 with a oil thermostat..that rite their will make a boat load of differance..

are saying oil cooler may not be doing its job or maybe the oil is not getting back to the oil pan quick enough due to passages not big enough

no what im saying is his oil cool is not as efficient as it use to be with the engine being stock..most people will just install a pro charger and forget about the oil cooler until you get a trend like this one...when you add horse power you need to install a bigger oil cooler so it can maintain a desent oil temps and maintain normal oil pressure