jet drive? or stern drive?

[Toby100000]

I have a 17.5ft speedboat that tapers to 6ft wide at the back and has a shallow v hull.
It had an inboard 90hp Renault engine that has now been removed as it was seized the boat has a mercruiser stern drive on the back I’m now doing it up. I have brought a Polaris 150 hp four stroke engine off a jet ski for it.
What I would like some advice on is do I fit the engine to the stern drive? Or do I use a jet drive that the engine is designed for? I also have a Berkeley Plaggio jet drive that came off a 4m rib would this work?
Any ideas would be great.
Thanks
Toby

[Frosty]

Toby - Its extrememly unlikely any one will have done a mod like this. Asking how do do it will result in absalute silence.

If your going to take on jobs like this you have to be able to plan them out and do it yourself. I for instance have no idea what the back of your Renault engine looks like nor do I have any idea what youir Polaris looks like but some how you have to mate them together central along with the drive. A jack shaft may be adopted where as the engine alignment doesnt matter. How much room do you have? compaired to what you want to get in there.

As far as will the jet be better? put it on and tell us!!.

A very difficult question

[CDK]

Unlikely, maybe... I converted a good norwegian boat with twin Mercruisers to Berkeley jets.
It involves some GRP work and you need a well equipped toolshop to make the parts you cannot buy anywhere or only against ridiculous prices. But you will be disappointed at the end. The efficiency of a jet is not comparable with props. V-8 owners can live with that, but in your case you'll surely notice the drop in performance. My boat did 35 mph with props, 22 mph with jets, powered by the same engines.
Attaching another engine to a Merc sterndrive isn't difficult, but you will have to make an adapter plate for the bell housing. Also the engine coupler from the Renault may not fit the flywheel of your new engine.