Hey guys, I have been using the crossover system with bypass hose and thermostat for several years now. Normally in the summer it runs 150deg running and about 160-170 at idle after warmed up. I use a 160 deg thermostat with 2 holes drilled in the edge. I have had the boat out 3 times in october this year. Because of the colder water temps the engine will not get any warmer than 120 deg on plane and 150 at idle. I expected the boat to be faster with the colder air temps but I was actually down 2mph from september. I am most likley done with boating for the year but want to figure out how I can get the temps up a little for next year. This has only been a issue when the water has been really cold, normally the system works perfect. I am thinking about switching thermostats in the early spring and fall. Anyone know any tricks?

I doubt 120 water temp vs 150 is making you boat 2 MPH slower. I also doubt that a lower oil temp would show on the GPS. Has anything else changed? Weight?

Engine will not go into closed loop. I could modify the computer program with the laptop but I would rather get the temp up. The PCM adds or subtracts fuel according to the O2 to get the perfect mix.

Depending on what exhaust you have, you can possibly add restrictors in the tails to slow the water down coming out of the engine. This should help build some heat when the water cools down.
Eddie

I thought you had HP500 engine?

Woops....I wasn't thinking about the computer adjusting for temps....just old school with carbs

Got a 489 stroker with Holley MPI kit with all forged parts. Running about 500HP, not really a "500HP".

Hmmm, that might work. I have the EMI thunders with the long stainless risers. I could experiment with some restrictors in the manifold to riser hose.
Thanks,

I should have been more detailed. Carb engine probably would not matter.

You can slip a pipe bushing in there. Maybe start with a 3/4Npt X 1/4 npt bushing. If that is too small, then start drilling the center 1/4 npt portion out until you get what you want.
Eddie