143 or 160 thermostat?

[98air]

What happens if I run a 143 in my gt 40 efi?

[shag]

Some say it is best to run the 160 in the EFI because they are sensitive to temp. IMO I can't imagine a <20 degree change would have that much if any effect on it. I have always run cooler thermostats in my boats and cars, but I know the newer ones are more sensitive to temps. My .02

[bchesley]

Absolutely nothing. I don't care what any one says I have run both and the boat runs exactly the same. If you are up north and need a hotter heater then go with the 160.

[DanielC]

The GT-40 likes to be a little warmer than a carb engine. The motor may OK with a 143 thermostat, or there is a possibility the engines computer will think the engine is not warmed up completely, and cause the engine to run a little richer to compensate.
So, the possibility exists switching to the 143 thermostat will cause your fuel consumption to go up. Or it may not. At over $4.00 a gallon for 89 octane gas, it is your choice.

[gtxragtop]

Engines are designed to operate at a given temp most efficiently with lowest wear. Operating outside of the designed parameters is not optimal.
The EFI engines seem to want the 160F. Stick with what the manufacturer states to use.