4-cycle snowmobile engine?

**GTS225** · 10-06-2021, 10:52 PM

Looking for a little advice.
I have the opportunity to pick up an Artic Cat, 4 cycle snowmobile engine, (actually the whole sled), for a mere $50.
I'm thinking it might make a suitable mini airboat powerplant, with horsepower to spare.
From what info I can find on short notice, it's a Suzuki-built 3-cylinder, 660cc, EFI powerplant, of 45 HP. Even with it's liquid cooling, it shouldn't be hard to fabricate a closed loop cooling system for it, and utilize the prop wash for air flow.

Any one care to advise me with a few pros or cons?

Thanks.....Roger

**GTS225** · 10-15-2021, 07:59 AM

Well, I figured it might be a long shot. I suspect a huge majority of you live in the southern states, and have never seen a snowmobile, much less up close.

I had to try, anyway.

Thanks.....Roger

**Bart** · 10-16-2021, 10:54 PM

it is good to see a new project starting...at 45hp. It sounds like you might have a 2002 vintage? What style of redrive are you thinking of using, and ratio? Depending on what year of motor. The max rpm is different.. 2002 is 6000. & in 2003 they changed the camshaft and exhaust. the rpm went up to 7000 and 53hp. A closed loop system for cooling would be simple. most of the big boats place the radiator below the motor, all you would need is a air vent at the top of the system to get rid of any air... if that doesn't keep it cool enough. one could alway place a temp disc on the radiator, that would turn on a electric fan when needed.... as for the crankshaft is it tapered or the flange style? It will be fun to see some pictures and hear what ideas you have up your sleeve...

**GTS225** · 10-17-2021, 10:57 PM

Well, Bart; I don't have it in my possession yet. Been a bit busy with remodeling a few rooms in the house. I should get out and get it home before a scrapper gets it from a local tow yard.

I'm pretty sure it's the early one. Redrive is something I'm not completely sure of yet, but I'd like to keep the engine low in the hull for weight distribution. I'm leaning toward a simple, multi-V belt drive, but I'd have to really slow it down to keep from spinning a 60" prop over supersonic.

I'm thinking a wood hull of about 13 feet, with a 72" beam at the gunwale. Hoping the powerplant isn't terribly heavy, as I'm thinking two seats. One between the prop and mid-ship, the other forward of the midship line. Both setting low in the hull. Leaving about 16" of flat deck along both port and starboard sides, and perhaps 3 feet of flat deck on the bow. Something that could be used to get into and fish some shallow backwaters around a few lakes and rivers in Iowa.

Nothing is in stone at this point, though. Just figured this might be a decent powerplant for a starting point. I do hope it's a straight shaft, though, and not a tapered one.

Roger

**Bart** · 10-18-2021, 10:21 PM

there are lots of options out there, one thing to remember with a v-belt set up for every 10 horse, you need 1 belt, so for 45 hp, you would need a 5 belt setup. Here is a picture of a Subaru EA81 motor I came across last summer out of a hovercraft. What intrigued me the most was the wooden driven hub

**GTS225** · 10-19-2021, 08:00 AM

Well, the setup is similar to what I had visualized. That wood pulley is unique.
Hmmmm......maybe a cog belt is in the future. With the advent of relatively cheap blower drive pulleys available, a guy should be able to find what he needs.

Roger

**Bart** · 10-19-2021, 11:07 PM

cog belts with the blower drive pulleys can give one a lot of options... the belt industry has came a long way in the past 30 years... I remember spending 80 dollars for a belt for my sled in the 90's, and having them last only a hundred miles if i was lucky, then on my last sled a 2016 polaris 800 I had the chain case replaced with a belt drive set up. they sure could take the abuse of a 150+ horse motor... and last for 1000 to 1500 miles... with no problem...
I do have a 2 to1 ratio with a 16 micro groove pulley set up.
at the moment I am using a 5 v-belt setup. with 9.5" center to center.
It is all about you doing a little research and finding what would work best for you.. there is vender https://www.j-birdengines.com/ J-bird engines that has a lot of different set ups. He mainly deals with ultralights. But he might have something that would work for your set up also... also if you need a custom pulley made. The machinest for Arrow Prop will and can make custom pulleys for you. He made my drive pulley for my 084 motor. It turned out nice. and they didn't go over board on the price... I wish I had the time to go down south and walk around a ultralight air show.. just to see all the different ideas that are out there.

**GTS225** · 10-20-2021, 06:59 AM

Thanks a bunch for that J-bird link. That's just a 5-hour drive from me, so I could run over there with my engine for a fitting.
I'll check out Arrow Prop, too. I have a link saved for an outfit in California, that would even calculate the drive ratios for you, once they had your engine info and prop intentions. Low cost hub assemblies, and modular, ground-adjustable pitch props.

I've also thought about a VW engine and direct drive, but VW stuff is getting a bit expensive anymore. It wouldn't be too terribly hard to build a 1/2 VW, or use the whole four cylinders. I'm just a bit concerned about all that weight being that high in the hull.

We'll see where things go.

Roger