Originally Posted by blue thunder

I wonder if you may not be asking for too much out of a closed cooling system hp engine? Mine with cc will start to climb if I run more than a minute or 2 at WOT. I ususally won't spend that much time at wot without settling back a bit to cool things down. How much coninutous wot time are you wanting to see with this setup?

Originally Posted by KWright

I understand what your saying my point is if your cooler is cooling it to 190 deg cooling it more before the cooler will only close the oil cooler thermostat
. right so its reaching those hot temps before the pan so the damage is already done.

Originally Posted by Rage

Yes. That is why I shut it down these days when it starts to get hot. You suspect that there is some motor damaging friction/detonation/etc. problem in the engine causing the oil temp climbing problem. I have checked out every suggestion as to what that might be for years now and found nothing to date. All I did find was inadequate oil cooler and feed lines early on and fixed that. Now I believe it is more likely that the 496 block has a HP limit with its standard bearing set up do to the resulting oil flow rate limit that bearing clearance produces. I have found other examples similar to mine with the same problem and only recently someone (a professional engine builder and mechanic) who also after many years looking at everything under the sun found the bearing clearances to be the problem at the high HP for the 496. I still appreciate and am listening and evaluating everything that is proposed but given how long I have been at this many are repeats. Does this make any sense to you?

Originally Posted by Rage

I have finally confirmed the reason for my engine oil temp problem during extended WOT running. Insufficient oil flow rate through the oil cooler for 625hp. An engine builder/mechanic built a pair of Whippled 496's for a 47 foot tub. So ~650hp though he claimed they dynoed 731hp. The engines are run at WOT for extended periods of time to push the heavy boat and oil temp was excessive. These have the same identical oil cooler as I do (Hardin 3x18 thermostatically controlled). Over a period of years of trial and error and insufficient success he finally increased the bearing clearances from 0.0025 to 0.0030 & 0.0035 rear main to increase the oil flow (through the oil cooler) and went from the 8-9 GPM Melling HV oil pump to an adjustable 15 GPM external oil pump to maintain the necessary oil pressure with the increased bearing clearances. That finally solved it.

I may eventually copy that but in the meantime I am looking for a work around that does not require pulling the engine and tear down. My first thought is to strap a radiator core style to the bottom of the crank case pan and run sea water through it to cool the bottom of the crank case and there fore the hot oil. Comment? Other ideas/products?

Originally Posted by Raylar

Rage:

We set all our high horsepower 496's with .0025-.003" main bearing clearance, .003" bearing clearance on the rods and we have no oil overheating issues on our engines when we use the 10778 oil pump, adequate size lines and fittings from the block to the oil filter and then to the cooler and back to the block. WE ONLY USE THE "ALUMINA" SERIES BEARINGS AND YOU SHOULD NEVER USE "H" SERIES BEARINGS ON THE STOCK GM 496 CRANKSHAFTS! If you have everything correct and assembled and plumbed correctly and a good oil cooler sized as yours with a properly working oil thermostat you should not be having a problem you are suppossedly seeing and expierencing with your oil system.

Best Regards,
Ray @ Raylar