ToddP
03-08-2004, 09:07 PM
After just spending nearly $200 per piston for my rotax engine, I started thinking alternative engines. There's a guy at my fire station who is always building a new snow mobile. He's a polaris guy and has nothing but good things to say about their motors. I also have two polaris Jet Skis and they have never even hiccuped. They always start, run great and have smooth power all the way from idle to full power.
Anyway after talking with John (the snowmobile guy) for a couple days, we're thinking the Polaris 700 twin probably is the best alternative. Apparently the lower end on these engines is just about bulletproof.
They are rated stock at 118 HP at 8150 RPM.
Here's what I'm thinking. Set my max RPM at 7500 RPM. According to the attached dyno chart the engine is still making about 105 HP. Lots of power to climb. In addition for normal cruising around you will probably run closer to 4500 utilizing maybe 50 HP (an estimate). This is opposed to the 5500 - 5800 we see on 582's or 532's to maintain the same HP.
Alright so how about the arguments:
1. Its not built for aircraft
Well, I personally don't think there is anything very special about the rotax aircraft engines except price. I really don't believe that Rotax's tolerances or quality control are any tighter for their aircraft engines than they are for their Ski-Doo Snowmobile's or Sea Doo Watercraft.
2. Not Dual Ignition.
Well, neither is my 532. However the polaris is a much more modern electronic ignition system and according to the snowmobile guys, never a problem.
3. Need Redrive. Yes I do, any good ideas? I've seen people have used the Rotax C box on Subuaru Engines without a problem. So obviously it can handle the 100 HP. The easiest would be an adapter to use the Rotax Box at a 3:1 reduction this wold get the prop RPM down to 2500 at full speed.
This engine would weigh no more than 15 lbs. more than my Rotax 532. The fuel burn would probably be lower because it wouldn't be running nearly as hard. The engine can run well below its rated top RPM providing a large margin of safety while still providing lots of power. The maintenance costs are way less than rotax.
I personally don't believe the polaris would be any less reliable than the rotax engines. In many respects they have made great improvements to their engines that Rotax has not. I wouldn't go so far as to say they would be more reliable, but I believe just as good.
I welcome anyone's comments or criticism. My skin is thick, so let me have it. I would also appreciate any ideas or concerns that people may have.
The lower line is the stock Polaris 700 Twin.
Anyway after talking with John (the snowmobile guy) for a couple days, we're thinking the Polaris 700 twin probably is the best alternative. Apparently the lower end on these engines is just about bulletproof.
They are rated stock at 118 HP at 8150 RPM.
Here's what I'm thinking. Set my max RPM at 7500 RPM. According to the attached dyno chart the engine is still making about 105 HP. Lots of power to climb. In addition for normal cruising around you will probably run closer to 4500 utilizing maybe 50 HP (an estimate). This is opposed to the 5500 - 5800 we see on 582's or 532's to maintain the same HP.
Alright so how about the arguments:
1. Its not built for aircraft
Well, I personally don't think there is anything very special about the rotax aircraft engines except price. I really don't believe that Rotax's tolerances or quality control are any tighter for their aircraft engines than they are for their Ski-Doo Snowmobile's or Sea Doo Watercraft.
2. Not Dual Ignition.
Well, neither is my 532. However the polaris is a much more modern electronic ignition system and according to the snowmobile guys, never a problem.
3. Need Redrive. Yes I do, any good ideas? I've seen people have used the Rotax C box on Subuaru Engines without a problem. So obviously it can handle the 100 HP. The easiest would be an adapter to use the Rotax Box at a 3:1 reduction this wold get the prop RPM down to 2500 at full speed.
This engine would weigh no more than 15 lbs. more than my Rotax 532. The fuel burn would probably be lower because it wouldn't be running nearly as hard. The engine can run well below its rated top RPM providing a large margin of safety while still providing lots of power. The maintenance costs are way less than rotax.
I personally don't believe the polaris would be any less reliable than the rotax engines. In many respects they have made great improvements to their engines that Rotax has not. I wouldn't go so far as to say they would be more reliable, but I believe just as good.
I welcome anyone's comments or criticism. My skin is thick, so let me have it. I would also appreciate any ideas or concerns that people may have.
The lower line is the stock Polaris 700 Twin.