CAN YOU RUN A THERMOSTAT WITH THE CROSSOVER SETUP?
IT HAS TWO HOSES COMING FROM THE TOP OF THE HOUSING AND THEY GO TO THE MANIFOLDS. IF THIS IS TRUE THEN THE MANIFOLDS WOULD NOT SEE WATER UNTIL THE THERMOSTAT HITS 140F CORRECT?

I have heard of lots of people running that set up.
They drill three 1/8" holes in the outer ring of the thermostat to allow some water to get through.

Depends on your set up . You have to have some water at all times going through the exhaust ,if not you will crack them . Some housings have 3 tubes .One for the main water outlet then one for each exhaust bypass . I don't think you are supossed to use a thermostat with it .They are for more flow all the time .

Slingshot,

You can run a thermostat with a water crossover kit, but as DJD mentioned you need to drill a hole in the thermostat to allow water to flow through. In addition, you need to use the bypass hose that goes from the crossover to the thermostat otherwise the manifolds will not get enough water at idle. If you do not have the fittings for a bypass hose, I would suggest running restricter washers instead of thermostats. Unless you are running an EFI motor package, then restricter washers will not work because the operating temp. needs to be between 140 & 160 degrees. Restricter washers typically keep the engines running very cool and will make the computer think that the engine has not warmed up enough and continue to throw fuel at it.

Hope this helps,
Don Baca
Triad Performance Marine

I PUT RESTRICTOR WASHERS IN IT

Holes drilled in the t-stat alone will not flow enough water thru it until the stat opens. Do the math, 1-1/4" incoming, 3) 1/8-3/16" holes out going. Ain't going to happen. Your looking at blowing intake gaskets cause your water pressure will go thru the roof. If you are going to run a crossover with a t-stat, you need a bypass hose at minimum.
tpmarine covered all the bases.

I run a crossover set up with a thermastat and bypass I got from CP Performance. Works perfect and temp stays at 150 no matter how I run.

B.R.S.
Whats your water pressure do you know?

With a 3 hose housing the exhaust will see water when the thermostat is closed-drilled or not. The water actually flows from the bypass up to thermostat housing through the bypass hose.

Last season I tried the crossover with a by-pass. My water temperature would constantly go up and down from approx. 160 to 220. The thermostat had one small hole that was about 1/8". Does anyone know why it would do this?