ampa

hallo and happy new year: on a water cooled boat engine (cmb 90 evo) how can I determine if the amount of cooling is good? my "agricultural" method is: I run full throttle the boat for 3 minutes and if I can hold my hand on the waterjaket these means too much cooling and I reduce the water flow on the water line with a tie wrap ,if i can not keep my hand on the w/j is ok, if the w/j is do hot that i can not touch it I increase the water flow .I am shure tath exists better ways to determine how much cooling is needed . running a overcooled engine ca harm it?

Blackout

What you have been doing is good. Yes, overcooling an engine can be bad. The sleeve needs to expand properly..... An infrared pyrometer can get you exact head temps, but your method does the job well.

amax

Engine temp in a Nitro engine is controlled by 2 main factors.
1st: is Fuel Mixture
2nd: is Water\Cooling System.

The richer your fuel mixture the Cooler the engine will run.
The Leaner your fuel mixture the Hotter the engine will run.

If you have leaned the engine to the point it's affecting the Glow plugs, and the engine Still runs Cool, Then it's time to restrict the water flow.

coriolan

Over cooling is an issue only with smaller displacement engines(bellow .45/7.5cc). A .90/15cc engine produces lot of heat even with low nitro %..

ampa

thanks for your answers: can someone tell me how many degress must have the waterjaket?, I suppose 70/80 celsius, if the engine is run cooler can these affect performances?