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trickskier
06-19-2008, 01:30 PM
Hey Jim,

Why are we running 160 degree thermostats in our boats instead of 195~210 like automobiles? I thought higher operating temperatures produced more horsepower and less emissions?

dsoby
06-19-2008, 01:42 PM
I believe that it is a Coast Guard safety issue.

shunra
06-19-2008, 02:27 PM
Hey Jim,

Why are we running 160 degree thermostats in our boats instead of 195~210 like automobiles? I thought higher operating temperatures produced more horsepower and less emissions?

I ain't no Jim but I think it has to do with the fact that cars have a pressurized (closed) cooling system. The boiling point of liquids goes up when under pressure. In an open system like a boat there is no pressure in the cooling system thus the lower operating temps. I could be wrong.

JimN
06-19-2008, 03:38 PM
Because cars and trucks have a radiator and that cools more efficiently than the heat exchanger in a boat. The gauge may show 160-180 but when it's hauling, it's hotter. Also, 160 buys some time if the impeller goes away. Yeah, hotter runs more efficiently but how long does a car run at, or near, WOT? The last thing a boat motor needs is to be run lean at WOT. Besides, emissions aren't tested (yet) on boats and since they aren't, a little rich is OK. Obviously, we don't need boats puking gas all through the water, burned or unburned, but there's a huge difference in how a boat is driven when compared to a car.

trickskier
06-19-2008, 03:43 PM
I ain't no Jim but I think it has to do with the fact that cars have a pressurized (closed) cooling system. The boiling point of liquids goes up when under pressure. In an open system like a boat there is no pressure in the cooling system thus the lower operating temps. I could be wrong.
Sounds logical...............Also, it maybe due to the fact that the water temperature rises when the engine is shut off and the cool water from the lake might crack the engine block when restarted.

trickskier
06-19-2008, 03:45 PM
Because cars and trucks have a radiator and that cools more efficiently than the heat exchanger in a boat. The gauge may show 160-180 but when it's hauling, it's hotter. Also, 160 buys some time if the impeller goes away. Yeah, hotter runs more efficiently but how long does a car run at, or near, WOT? The last thing a boat motor needs is to be run lean at WOT. Besides, emissions aren't tested (yet) on boats and since they aren't, a little rich is OK. Obviously, we don't need boats puking gas all through the water, burned or unburned, but there's a huge difference in how a boat is driven when compared to a car.

Thanks Jim!

Maybe that's why I break out in a rash everytime I get in the lake?!?! :confused:

JimN
06-19-2008, 04:57 PM
"Also, it maybe due to the fact that the water temperature rises when the engine is shut off and the cool water from the lake might crack the engine block when restarted."

Next hot day, turn the key to ON before starting it and look at the temperature after it sits for about a half hour. If the air temp is over 90, I would guess the motor temp will show about 240. Cars heat soak, just like boats but there is definitely a difference in how much shock a boat motor experiences when it's started.

trickskier
06-19-2008, 04:59 PM
I'll check it this weekend. Thanks again Jim!