killfast1

I will be upgrading to twin aluminum 540/572"s putting out about 700HP normally aspirated. What size coolers should i run? Also currently running mercruiser 420's. Can I run the coolers for the 540/572's with these motors until I convert over. I plan on using coolers with thermostats. I need some for these motors and I really only want to buy them once.
thanks.

Wes Burmark

Going to the Hardin Marine site they list the following as the standard cooler combo used by Mercruiser:
Combination Engine Oil & Power Steering Or Transmission Cooler 620-400 Your Price $229.99

Combination Engine Oil & Power Steering Or Transmission Cooler, 2" Diameter, 19" Overall Length, 3/8" NPT P/S and 3/4" NPT Oil Connections, 1-1/4" Water Connection

All the same features as our other coolers except it is designed as a MerCruiser replacement cooler for the most common V8 engines. The only noticeable difference is the use of 3/4" NPT oil connections providing a higher volume flow capacity.

The cooler they list for a 700 hp application is longer and 3" in diameter. The 3" model has over twice as many tubes.

killfast1

Could I use the bigger cooler with a 468 at about 450HP? Would it hurt anything? I do plan on using a thermostat with the cooler.

BenPerfected

Bigger oil coolers won't hurt as long as you have an oil thermostat that allows you to cook off the condensation.

killfast1

Cool thanks.

lightning jet

Like ben said a big cooler is great as long as you use a thermostat........3x14 bundle 1.1/4 water and 3/4 npt oil