What is the best bearing choice séries on the rod and main on supercharge engine? P - H or M séries?

That is for an upgrated merc 525sc with stock forged crank,
Calies compstar H beam rod with arond 650HP for now but i want to trying to get 700-800 HP in future.

Thanks for the recommendations.

I like to use H bearings with steel cranks.

Coated

A hard being is a good choice for a marine application. The coating takes things up a notch as far as "nice". Clearances depend on oil weight and type as well as oil temperature.

If the stock 525SC crankshaft has an induction hardened surface and is accurately finished and polished we have had really good results with the newer "alumina" series bearings as long they are matched to the fillet radiuses on the crankshaft. The micro grooving on the new Clevite "alumina" rod and main bearings have a tendency to hold a more even oil film barrier across the loaded surface even at higher oil pressures and the harder silicone mixture will just micro-polish a good crank surface. These bearings will also, with their harder surface, tend to spit out small debis particles and dirt and keep those in the oil where the filter can remove them instead of imbedding as they tend to do in the older bearing types like the tri-metals. Again, a great correct surface and clearance on a crankshaft will have more to do with bearing life and problems than the bearing material itself. Get the crankshafts to a good shop who is really expierenced and equipped to properly check, measure and put an accurate size and finish on the journals, don't skimp here, this is the base foundation of a good shortblock! Also don't shortcut aligning the crankshaft mainline in the block. Straight crankshaft + crooked block= poor shortblock and rotating assembly.

Best Regards,
Ray @ Raylar

As for the bearing clearance Merc spec is .002 to .003 in for the no:1-2-3-4 main and for the no:5 main .003 to .004 in.

For the rod between .002 to .0035.

They also recomand run with 20W50 oil.
Last summer i have run with the Royal Purple XPR 20W50 oil.

I dont have oil temp gauge but i run the engine with thermostat for the engine cooling to get warmed up faster.

So with that main and rod clearance does the Royal Purple XPR 20W50 is a good choice???

Thanks

Thanks for the good details.

Between .0028 and .0032 on all std mains and rods and up to .0035 on the rear main would be nice. For oil weights I generally run in the 15-40w range with a good synthetic after breakin. You do need to add oil temp gages. I used the clevite h during winter refresh this year. Next go round I think I'll try the ACL coated. I'm not a big fan of the narrow h clevites since they changed them as I see how that might bleed off oil pressure more so than when they had the fillet in the bearing.

I hope that i will have any problem with the clevites h narrow,
That is what i have buy for my rebuilt.
It is my first time rebuilt for a big block so i dont know what is good and what is not...
This is what the performance parts seller have sell to me after i have told him (I want only the best parts.)

You won't have any trouble with h clevites, that is just a theory of mine. I been using them for a number of years and never have oil pressure issues. I do run a good oil pump though in the 10778c melling.