I called pro charger and the tech did not recommend I run without a thermostat. He said to run the same one the motor came with stock. He did also say to check the tune and that it shouldn't hurt anything to run it cold, if it was tuned to run that way...

Be careful with water psi running a t-stat as that system uses a crossover instead of factory recirculation. The t-stat will close off all water coming in, other than what will go out to the intercooler.

I'd probably drill 3 x 3/16" holes on outer circumference of t-stat and get yourself a water psi and water psi regulator in case needed.

BTW: You'll still have a problem warming the motor up to proper 140 (what Merc usues for t-stat) because you won't be recirculating any warm water back to the engine.

I'm on a lake that freezes too, so I know first hand how much crossover systems suk when the water is still cold.

And yes, unless programmed for it, your EFI computer will still be in cold start enrichment until water temp get's over 120F or so.

Is the cross over your talking about the piece that connects the to water holes that a stock Chevy water pump normally uses? My water neck looks differently than the stock ones I found online for the mercruiser so I don't even know if a T stat will even fit, gues all I can do is try.

Could a guy install a ball valve in the let inlet house from the water to the sea pump too slow down the water some?

Does your boat run harder when the lake warms up?

Only EFI without a t-stat. Again, EFI programming usually says 'Under 120' is in cold start enrichment. You need this programmed different to run under this temp.

I run carb'd now...so it's actually faster with colder water. Cold start more tempermental though of course. I don't use chokes.

You have the ATI crossover system. The Housing on top of intake manifold t-stat boss will house a t-stat, but it's only bypass is a small one to the Intercooler. This will not be enough to keep water psi's down when using a t-stat and when you are on the hammer. The Merc one is desinged to be used with a recirculation pump (on a car this same pump is called the water pump) and thus recirculates water back to the engine so it can warm up.

Crossovers and cold water are a beatch and will cost money and time to set it up. Southern engine builders don't believe us but I'm done listening to them not getting it. Different worlds.

There are some Programming companies that sponsor this site, I would look them up and call them about EFI programming for colder water before you do anything and break anything.

Boat engines can build crazy water pressure if the system is closed off to much and the end result can be a ton of water in your oil. Seen it a bunch of times.

Have fun and please be safe since you are a newby playing on a non-newby set up.

Thank you. I will leave it alone for now and run it as is. I'll see what I can find out about the tune before I make a change. It did come from the south lol..

One more question on the procharger, its it normal for it to only make boost while under hard throttle in the upper rpm? Seems like it should be at 5 psi from idle on up...thanks again!

Throttle setting determines how much air can go in....#1

#2: Centrifugal blowers uses gearing that greatly multiplies impellar speed. Some call it a step up ratio. Therefore, it will have a rising rate of boost (vs engine rpm)when the throttles are fully open as compared to a roots blower that will produce same psi at low speed as it does at high speed with throttles wide open.

Some +'s and - 's to all supercharger types.

SB, can you tell me what you know about water pressure? Ran mine wide open today and the highest was about 13 psi. A buddy with a similar motor said that's to low and that I need a restrictor to raise it some. He also thought that would slow down the water some and might raise the coolant temp slightly...

Found some more info out about my boat. I put a restrictor with a 5/8s hole in it today and ran it and still not over 100 degrees. Gunna make one with a 1/2" hole and try that next. Water psi went down instead of up so I'm going to replace my sea pump now to. Called the company that tuned my computer. He told me its good to 7psi boost and that the cold enrichment mode is set at 105° so that explains why its never running its best. I'll keep going with smaller restricters until I get the temp above 105 but making sure the water pressure stays under 30 psi at wot... The exhaust is the Dana marine torque flow manifolds with the stainless risers. Nice pieces. Kinda wonder if my props a bit small tho.. Lapped 28p. My buddies similar set up runs a 33p lapped so Idk..

My 25 Eagle had a side mount whipple on the 502mag with Dart heads & EMI Thunder exhaust with an IMCO -2" shortie. I was running a 30p labbed Bravo 1 & it would bounce off the rev limiter @ 5200 rpm until I twisted a propshaft & blew up the lower unit. It was radared @ 93 mph during a shootout we had but everyone who had gps said the radar was 5 mph slow. It chine walked so bad you couldn't hold it floored for too long.