SoCal Jet Boats
Discussion => The No Wake Zone => Topic started by: daymiene on June 02, 2017, 09:22:37 AM
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What's up everyone I'm new to the jet boat scene here as well as So Cal Jet Boats! Now I understand that there is some head work thats needed to be done to sustain constant high rpm in a boat motor correct? Is there anything else besides the head work that I should look into having done for the sake of my engines life? Also what exactly is done to the heads to handle being in a boat?
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Sorry for the grammatical error in the title lol
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You also want to make aure that you have a thermostat set up that won't allow too much cold water through the motor thus never letting the motor reach proper operating temperature (160-190°ish).
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Welcome to SCJB and jet boats.
Yes an engine should be built specifically for a jet boat. Can you use a motor out of an old truck? Yes but if you run it like we like to run jet boats, it probably won't last to long.
Jet boat motors have bigger clearances (piston to wall, crank bearing clearances, ring gap). There are some other things, but I'm not a mechanic, just know some stuff from reading the forums for a long time.
Best bet is to contact an engine builder that KNOWS jet boat engines. Bostick is the main guy here at SCJB.
I found this thread that has some info about building a jet boat motor:
https://www.socaljetboats.com/engine-mechanical-electrical/let's-stir-the-pot/msg256034/#msg256034 (https://www.socaljetboats.com/engine-mechanical-electrical/let's-stir-the-pot/msg256034/#msg256034)
There have been a lot of discussions about the subject, so it's time to get familiar with the search feature. ;D
You also want to make aure that you have a thermostat set up that won't allow too much cold water through the motor thus never letting the motor reach proper operating temperature (160-190°ish).
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Most jet boats don't have t-stats and run an open water cooling system, hence the reason for some of the bigger tolerances.
They do make a t-stat kit but I think the general consensus prefers not to run them.
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This applies to a open loop cooling system only.
Certain clearances will need to be adjusted because temperatures are drastically different compared to the same engine in a car.
For example, you have a high volume of water flowing through the the engine at a high velocity. Therefore, thermal expansion of the cylinders and valve guides will be less than in a car. However, the temperatures and thermal expansion of the pistons and valves could be greater. More clearance is needed to compensate.
IMHO, only oil temperature is relevant and water temperature is meaningless.
There are several posts on rule-of-thumb clearances, but I can't say how that would apply to your engine.
You could run a closed loop cooling system with a water-to-water heat exchanger and an automotive style water pump (and thermostat).
You don't want to run a thermostat in an open loop cooling system, it will never open before the engine melts down.
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Welcome to SCJB and jet boats.
Yes an engine should be built specifically for a jet boat. Can you use a motor out of an old truck? Yes but if you run it like we like to run jet boats, it probably won't last to long.
Jet boat motors have bigger clearances (piston to wall, crank bearing clearances, ring gap). There are some other things, but I'm not a mechanic, just know some stuff from reading the forums for a long time.
Best bet is to contact an engine builder that KNOWS jet boat engines. Bostick is the main guy here at SCJB.
I found this thread that has some info about building a jet boat motor:
https://www.socaljetboats.com/engine-mechanical-electrical/let's-stir-the-pot/msg256034/#msg256034 (https://www.socaljetboats.com/engine-mechanical-electrical/let's-stir-the-pot/msg256034/#msg256034)
There have been a lot of discussions about the subject, so it's time to get familiar with the search feature. ;D
Most jet boats don't have t-stats and run an open water cooling system, hence the reason for some of the bigger tolerances.
They do make a t-stat kit but I think the general consensus prefers not to run them.
Lighted me!
I forgot to mention, if an open loop cooling system is used, you may have to take extra steps to seal the water.
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Appreciate all the info guys! Really. I'll take in all the knowledge I can when available.
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Lighted me!
I forgot to mention, if an open loop cooling system is used, you may have to take extra steps to seal the water.
I wouldn't say I lighted you. It took me about 45 mins to research and type out that response. ;D
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I wouldn't say I lighted you. It took me about 45 mins to research and type out that response. ;D
I'm on my cellphone when I should be working. Shhhhhh. Don't tell anyone how long I was screwing off? I don't have the texting skills of a teenager.
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lol don't even ask me how much time I spend on here when I'm at work
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