For you guys that have built 496's from your Gen VI 454's, did you have to upgrade from the stock Merc oil cooler or is it adequate enough to support @ 500 HP? Did you stay with the circulating pump or go to cross-overs?

TIA.

I had problems on 496 with stock gen 6 cooler. When running hard the lifters would loose there pump. IMO the oil lines are too small also...

Sounds like a oil viscosity issue. Did you verify temps?

No, you will need to get a bigger aftermarket cooler. Ask me how I know? I learned the hard way. You will also want to upgrade your lines and fittings.

IMO, its always best to run a larger oil cooler than needed, coupled with a oil thermostat. The stock merc lines and fittings do leave a bit to be desired from an oil flow standpoint. I have -12AN lines with full flow 90's .

My thought is to get a used oil temp gauge (I have one) and a sender and just run a wire around the hatch so you can tape the gauge in the helm area to see where you are. Run the boat at WOT for 5 min and see where your oil temp goes. If you stay in 250 degree range you will be fine. The bigger cooler can keep your oil too cold (won't burn off the condensation) for normal use unless you add an oil thermostat. IMO, there are likely bigger priorities on the wish list.

Did you make any other changes to the engines other than adding a 4.25 crank? Or, how much power does the new engine make?

I personally wouldn't run my oil temp at 250*. With my Merc HP style oil thermostatic filter heads, and a bellhousing plate cooler, my oil temps cruise at 180* all day, and when I run hard, they go to 210-215, no higher. Absolutley no condensation issues.

242ls has a nice set of coolers for reasonable $$

I have a nice pair of coolers and brackets that came off 700 blower motors I am not using. Will take $250 plus the ride if you're interested. Send me an email address and I'll send pics.

Motors have not been dyno'd yet. Should get run later this month. These are being built for a buddy of mine and I asked him if his builder was going with larger coolers. He seemed to think not. I told him I'd put a thread out on OSO to see what other's experiences have been.

These motors started life as 330 HP Gen VI 454's in a '96 303 Formula. At @ 300 hours they were worked by Baker Engineering and made into @ 465 HP mills by way of Brodix II aluminum heads, roller cams, WP single plane intakes, Holley DP's worked by Nickerson, MSD ignition, and CMI E-tops. He hydro-locked one of the motors this past September and ventilated one of the cylinders. That block has been sleeved and he went ahead and had both mills made into 496's. I'm concened he might be reaching the limits of the stock oil cooler/lines.