Outboard or jet?

[cltch]

Debating... I have a 77 evinrude 200 I can put on my boat (techinically its on the boat with a jackplate). (16 challenger) or I am thinking it would be interesting to do a jet drive. The style on the sea doo jet boats if I can source one. I would like to see what it would do with a turbo motorcycle engine would do behind it. I have access to the turbo resources as well as to get the engine. I love boating and am used to the outboards but am not sure how hard it would be to source the jet unit I need (little one off sea-doo boat or jetski). Right now the boat needs a complete rebuild (the transom is soft on one side). I am very tempted to use the 200 and see how that goes but tinkering with a bike engine and turbo appeals for being unique and easily accessible (I ride and have a some decent connections). Thanks guys.

Ross

[cltch]

??? Someone had to have an opinion on this! Good or bad, I just think it might be interesting... But not sure if it would be practical or work...

[Bones]

Mercury sport jet maybe? They build them for inline four's and v 6's. If you use a mc engine what gear would use? I would think whatever is closest to 1 to 1. It would have to be a stout motorcycle engine to turn a jet, they eat up alot of hp.

[cltch]

The largest concern I have is sourcing the jet system. As well, I don't really know much about the performance figures on these. I can easily spin 12k and would plan on running 4-6psi on a turbo setup. I figure it would be an easy 200hp. I'm just not sure what the performance side of it would be. I would like to get a solid mid-60s boat out of this(I'm not sure if it would be very safe over that based on the hull design). However, the other option is a 200 evinrude on a 6inch jackplate...

[Techno]

You would need to add all the crap to support the new engine and drive system. This also puts the CG further forward. And makes it heavier.

Then you would have to assume a high spinning peaky engine could spin the pump with anything that approachs your expectations. Bikes have gears to keep the engine near its power curve. Boats normally don't have gears so the engine has to have the umph everywhere you'll use it.

I don't know the names but merc sells an OB version of a jet and also a jet drive that uses an inboard mounted OB engine. As far as the bike engine they are kind of tiny aren't they? A turbo isn't going to breathe if the engine can't spin? A merc is like 2500 cc in 6 cylinders.

[Riverman]

Don't bother. Soup up your 200, you will get much better results with less work, money and time.

I have a bit of a jones for jets too. But you need a LOT of horsepower to make them work right.

[cltch]

Techno: Yes a gear reduction would be necessary. But the newer 1000s have a fairly wide power band. As for the turbo, they actually respond very well to small turbos on light boost(I love riding but not crazy enough to do it on my personal bike). But thank you. Very good points.

Riverman: That is the dilemma, its a 1977 crossflow... Not sure how much it will cost to actually do decent work to it... That and it is a bit heavy on my boat, hehe... I'll get a picture of it up in a few days. The motor is actually mounted on the boat but I need a few things before I can try and take it out...

[Riverman]

There is a fellow on here that goes by BL, I believe he builds fast Crossflows. You should ask about a drop-on, way cheaper than messing with a jet. :)

[Knjhn]

Another turbo pont, I dont know how Honda solvs this problem(maybe with a soft touch rev limiter) but turbo engines dont decelerate as soon as you throttle back. They lag in deceleration. So when your gettin the intake (or even a prop) out of the water they tend to over rev. Thats why so many V8 IO's are supercharged, they respond to throttle input instantly in both directions.
Ken

[cltch]

Thanks guys. I decided I'm going to go ahead and do me restore with an outboard in mind. But I'm going to worry about purchasing something newer, lighter, and that is within the boat rating (for insurance). I am going to have to completely redo the transom on this boat and add knee braces. I appreciated the information.

Ross