Need help with custom engine swap fabricators help needed

[lamboman]

Hello everyone...new here and new to boating in general. I aquired a 1995 Thundercraft Typhoon 150HP with a blown powerhead. the person I got it from also gave me a good 150hp mercury outboard. His plan was to bolt the outboard powerhead to the jet pump... an he has the adaptor for the splines of the jet to the outboard powerhead. Basically I need to cut the shaft off the lower part of the outboard and use that to mate it to the jet drive...I am ok with this and it makes sense... and im ok with the need to make an adaptor plate to physically mount the powerhead to the jet pump.in theoy it seemed doable however thinking harder about doing this I totally forgot about cooling the engine and this is where I am confused and unsure? also I am unsure on the boats jet pump housing where water would come out of and what needs to be re attached and what needs to be capped off to make this possible?. I have attached 3 pics of the powerhead and its lower half that I will need to cut the shaft off...and one of the boats jet housing. I really need some help and input on this project...is this possible or am I crazy for trying this? has anyone ever done this?. Thanks.

 

[ddennis]

Re: Need help with custom engine swap fabricators help needed

Sounds like a waste of time, effort and a LOT of money! You have more than just cooling to worry about, you also have exhaust. The exhaust coming down through the lower unit is "tuned" to help generate not only the proper backpressure for the engine to operate properly, but also make the most HP.
Also since there will be now lower unit, there will be no impeller to pump water through the engine. By the time you have (or had someone else) design the proper parts and adapters from scratch, then had them machined, you could have bought a new boat. This is not a simple "stick in an adapter plate and let 'er rip" type install. This is a major engineering project for someone with more time and money than they know what to do with.

If you have the original engine parts, it would probably be MUCH easier and cheaper to rebuild it and put the outboard back together and (if it runs!) sell it to help pay for the rebuild!

Oh yeah! and welcome to Iboats! There is a ton of good knowledge on these forums!

 

[studlymandingo]

Re: Need help with custom engine swap fabricators help needed

There are companies out there that produce jet drives for standard outboards.

Remember, you lose a lot of HP with the motors when they are used as a jet. Why not rebuild the one powerhead, or just use the "new" 150 as a regular outboard?​

 

[lamboman]

Re: Need help with custom engine swap fabricators help needed

Thanks for the replys. I guess no one has ever tried this mod...I was thinking of just mounting the outboard on there too... but would it be hard to make that work and be to heavy on the back end? I would need a solid way to mount it and need to rig up a stering cable?. what do you think?

What is the chances of finding a proper powerhead for my jet?...my motor is not rebuildable. Thanks again,

 

[lamboman]

Re: Need help with custom engine swap fabricators help needed

I thought I had heard about some people trying do do something similar to this before? has anyone run across any websites?.


On another note if I was to bolt the outboard on what would I need?. I was looking at the mounting and it seems like it would be a challenge to make that work as it would need to mount to a flat diving platform at the rear of the boat.

 

[lamboman]

Re: Need help with custom engine swap fabricators help needed

Anyone? Is this swap possible or has it been done before?. and if I did just mount the outboard on the boat how would I mount it? etc?. Thanks,

 

[ricksrster]

Re: Need help with custom engine swap fabricators help needed

What was the original?

 

[lamboman]

Re: Need help with custom engine swap fabricators help needed

ricksrster what do you mean by original ?... is it possible to mount the outboard powerhead on a typhoon jet pump and how would I deal with cooling...and has this type of thing ever been done before?.

The other question / option is if I just mounted the outboard on the jet boat would it sit right and not be too heavy and how would I mount it to a flat diving platform on the back of the boat?.

I appreciate all the input.

Thanks,

 

[gotboostedvr6]

Re: Need help with custom engine swap fabricators help needed

make sure the transom is 1.5" thick or more, remove the jetpump, seal the hull and build it up with wood and fiberglass, cut the diving platform, install a 6-12" setback jackplate, bolt the motor on install new telleflex steering, get controls and go faster than when it was a jet and have more control

 

[studlymandingo]

Re: Need help with custom engine swap fabricators help needed

What Rick was asking is what motor is on the boat now. What powerhead is being replaced? If it is the same powerhead, then you'll just use the parts that are there; if it is a complete retrofit, then you will be much better off selling the outboard you have and using the proceeds to buy the proper powerhead for the jet drive that you have.​

 

[lamboman]

Re: Need help with custom engine swap fabricators help needed

The factory powerhead for the boat is a 150 HP Force / mercury sportjet. I have a powerhead off a 150hp mercury outboard that I want to replace it with...and have no problem making the engine adaptor plate and drive gear adaptor for the jet pump. My big problem is with the cooling how can I make that work and has this type of swap ever been done. Thanks again I hope this clears things up. I talked with the thundercraft dealer and they priced a new powerhead and it was nearley 8 grand...just not feasible for a boat like this, I just want to make it run again and have some fun and not break the bank.

More and more it seems easier to just retrofit the outboard to work on my boat.

 

[ricksrster]

Re: Need help with custom engine swap fabricators help needed

http://www.boatmotors.com/motorpart...&state=ny&zip=14801&hp=150&disp=&disp2=3&cyl=

 

[studlymandingo]

Re: Need help with custom engine swap fabricators help needed

There you go, the link Rick posted is for the replacement powerhead; you should easily be able to get that and more by selling the 150 outboard you now have.​

 

[wildlifeguy]

Re: Need help with custom engine swap fabricators help needed

this is a great thread guys.... a bit dated but was wondering what ever happened to the either the swap of outboard head to jetdrive or simply mounting an outboard onto back of typhoon boat (which I have and am willing to do if done before with some guidance). Apparently, there are a number of sportjet 90hp-150hp users out there in need of some assistance. I dont want to waste a great little boat because of a crappy engine.

m