So I am a snowmobile guy as well as a superjet owner, and I was wondering why my 600cc snowmobie engine makes 120hp and a 701 is somewhere in the 70's? Has anyone tried snowmobile engines in ski's? I run my sled at high rpm for extended times and it doesn't blow up so im not sure what would make it not watercraft worthy. Could some engine guru explain why a watercraft cant pump out anywhere near the same power per cc as a sled? Thanks knowledge would be greatly appreciated.
Other why do snowmobile engines make more hp per cc than watercraft 2 strokes?
- Thread starter firecatf6
- Start date
Aren't snowmobile primarily used for high speed? If you compare similar 2 stroke engines in sit down jetski's these days they are just as powerful but the power is produced in the upper rpms and the lower revs suffer. You also have to remember that the 701 was designed 17 years ago and was based on the 650 which is even older and they really haven't changed since.
Dustin Mustangs
uʍop ǝpıs dn
- Location
- Holland, MI
I'm sure there are a multitude of reasons, but for one a sled has a cvt that allows for a much more narrow power band which naturally leads to higher peak numbers. Skis are obviously direct drive which means they need to make good power from right off of idle (especially for freeride/style type riding) to peak rpm. You could put a cvt in a ski but the pump design would have to be totally different from what is out there currently to efficiently use that type of power. Unfortunately our sport doesn't have enough money in it to support the R&D effort and tooling expenses needed to get something like this off the ground.
Somewhat related, I have day dreamed before about a coupler that stores energy briefly (in a torsion spring for example) before delivering it to the mid-shaft. It would delay but increase the initial amount of power (ie hit). The idea could work but again all that additional power would likely be wasted in the form of cavitation unless you had a pump designed to take advantage of it.
Somewhat related, I have day dreamed before about a coupler that stores energy briefly (in a torsion spring for example) before delivering it to the mid-shaft. It would delay but increase the initial amount of power (ie hit). The idea could work but again all that additional power would likely be wasted in the form of cavitation unless you had a pump designed to take advantage of it.
- Location
- St.Louis Missouri
It seems as if snowmobiles also have more room for a better exhaust system. Just brain storming here though
- Location
- Central FL
just fired up my watercraft/snowmobile hybrid tonight. i'm hoping to shed some real life info on this after the weekend.
OCD Solutions
Original, Clean and Dependable Solutions
- Location
- Rentz, GA
I asked this same question years ago when my Seadoo 951 put out 130hp and my summit 800 put out 150hp and accelerated 10 times harder. When I installed the 900cc Crankshop billet cylinder and twin pipe setup, I was dying to try it out in one of my skis but was told by the time i got pipes to fit in the hull it would knock the HP down way too much.
Now that I have an X-Scream SS865 I don't think about it anymore. :biggrin:
Now that I have an X-Scream SS865 I don't think about it anymore. :biggrin:
- Location
- Central FL
i took a guess with the port timing on my engine. it's an 800 ves right now. total loss, 46 sbns, v force 3, and a powerfactor pipe. it sounds incredible compared to my octane. i've got two more engines i put together and can't wait to try. a ported 800 with slp head, and a 900cc setup 
i haven't been this excited in a long time haha
i haven't been this excited in a long time hahaSchmidty721
someone turf my rails
- Location
- WI
Air flow. The limitations a ski has in regards to intake track and exhaust size severely limits the output potential of the engines we run. What I would like to see is what kind of power some of the top builders in the PWC world could produce out of say a 1000cc twin setup in a sled.
waxhead
wannabe backflipper
- Location
- gold coast
Dustin mustang has it right
they have a cvt so they only have to make power in one speed range or at least a very small power range
Where a pwc has to pull of the dock to top speed.
the cvt changes gear and keep the snow mobile engine at the correct rpm much like a scooter
they have a cvt so they only have to make power in one speed range or at least a very small power range
Where a pwc has to pull of the dock to top speed.
the cvt changes gear and keep the snow mobile engine at the correct rpm much like a scooter
thanks guys for the info....i kinda figured most of it had to be either in the port timing aka what rpm range the engine is tuned to be best in and also the exhaust but i just wanted to hear some other suggestions. The power gap just seems so huge from sleds to watercraft but again its all in where you want the power at i guess
- Location
- Central FL
well peak torque is at the very most 5252 rpms. Malone's new 15-20k engine is sled based. lenzi's big boy engine is sled based. same with powerfactor. they all looked to be polaris based at that. the case design on the sled is better then yamaha's for flow. the stock exhaust on a sled doesn't look like it'd hold a candle to a pf pipe. they also run smooth bore 40's oem from what i've seen. so the carbs aren't bad, but again nothing special. so we'll see
Polish jet pilot
4aces4aces4aces4aces4aces
- Location
- Warsaw, Poland
The polaris sled motors look exactly (first glances) like some motors EME uses (the PV's, the cooling, etc). Looks like almost drop and go.... and an 800cc makes about 130 hp!
- Location
- Cleveland Ohio
I believe the EME still uses octane cases and a snowmobile cylinder.
- Location
- Sacramento, CA
Even a 440 motor would work, out of a doo or poo race sled. Would give killer low end and some descent top end!
- Location
- Central FL
you're right. my head was spinning from other things going on. that's where hp over takes tq. forgot my p's and q's for a second. either way my hybrid motor has a lot of potential after sunday's ride. i need to get the power down another 1k rpms and this will be a monster of a motor for a fairly cheap price. super super rich and homemade timing curve this thing is blowing the doors off my octane engine from the midrange up.