I have a whipple blown, EFI 454 magnum. I have closed loop cooling and had a 180 degree thermostat and the engine ran a steady 190-200 deg. I pulled the thermostat out and idled it for 15 minutes in the driveway on the garden hose- it never even got above 100 to make the needle move. Oil temp didn't move and it starts at 140. Should I take it for a run and see what it does WOT? Or should I put in a 140 deg thermostat so it doesn't run too cold? What is too cold for a 600HP blown engine?

You would like to see a little temp(120) to burn the condensation out or your gonna have problems. I run 140 stats with holes drilled around the circumference.

I agree with kaama 82 . Merc uses 143 degree stats which operates at 160 170. No thermostat is trouble as the water doesn't get forced thru motor. You see a false cool reading. if the sender was in the back of the motor it would read much hotter reading.
Jim

140 degree is where you want to be.

definately put a 140 thermostat in there ...... i run about 150 degrees

Okay a 140 is on order, thanks!

Hey
If You Have A Closed Cooling System Then You Need The ""high Flow"" 160 Degree Stat Thats What Merc. Uses. I Have Closed Cooling On A Small Block And I Put In The 140 Deg Std. Stat. And Over I Heated. It Doesn't Flow Enough Water Thru The Stat. With Closed Cooling Running 160/170 Deg. Isn't A Problem. Summit Has Them Plus Merc. Dealers.

Arizona Speed and Marine supplied me with a 120 high flow for a blower motor. See 125 at cruise and 130 at WOT.

You want to keep that blower motor at 140-160, or else you might get into a situation where you have detonaion. Cast iron heads don't like heat and boost at the same time.


Darrell.