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Rotax pro stock motor ?
Last post 09-11-2008 6:01 AM by toydoc. 13 replies.
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09-07-2008 11:58 AM
Offline PS4
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Posts 16

Rotax pro stock motor ?

On a 809 rotax motor that runs on ice and asphault,  which would be better?  1. A low reving motor(9000-9200rpm) that makes alot of torque   or a high reving motor (10,600-10,800rpm) that makes alot of hp?
09-07-2008 12:11 PM In reply to
Offline dyna-tek racing
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Re: Rotax pro stock motor ?

any time you can make good horsepower and torque at a lower rpm it increases the CVT efficiency and will be easier to transmit more power to the ground.i beleive you lose about 3-5% belt efficiency for every 1000 rpm increase.you can make either setup work for you but high rev motors seem harder to clutch.
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09-07-2008 8:09 PM In reply to
Offline PS4
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Re: Rotax pro stock motor ?

ttt
09-07-2008 8:16 PM In reply to
Offline Clayton
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Joined on 07-31-2005
Montreal Quebec
Posts 490

Re: Rotax pro stock motor ?

I would chose the lower reving, high torque engine. Some people have success with the high reving engines but it requires a very experienced tuner to adjust the engine beween heats and shorter intervals between rebuilds. The lower reving engine would generally be much more consistant.
09-08-2008 7:21 PM In reply to
Offline PS4
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Posts 16

Re: Rotax pro stock motor ?

With a higher reving motor, wouldn't you be able to gear it down so the sled would not loose short time and still run a good mph?
09-08-2008 7:28 PM In reply to
Offline tag
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Joined on 05-19-2006
Posts 134

Re: Rotax pro stock motor ?

torque gets you off the line

much easier to run with torque than trying to make it all with hp
09-08-2008 7:36 PM In reply to
Offline PS4
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Posts 16

Re: Rotax pro stock motor ?

on the ice do you need alot of torque or will the hp shine done the back half of the track. does anyone know what Mike Knapp's old vmax 800 used to run for rpm?
09-08-2008 7:46 PM In reply to
Offline Clayton
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Joined on 07-31-2005
Montreal Quebec
Posts 490

Re: Rotax pro stock motor ?

There are some very fast high reving, narrow powerband 800's on the ice, but they need tons on maintenance and constant tuning to keep it in the powerband. The low reving engines are much easier to tune and more consistant. If you can't tune the "screamers" they will be a turd. A torquer will always run decent even if your tune up is out to lunch. "There is more than one road to Paris" take the one that suits your skills / knowledge best.
09-09-2008 2:36 PM In reply to
Offline Iceman 700
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Joined on 10-20-2005
Posts 555

Re: Rotax pro stock motor ?

Well said Clayton, Knapp used to run that V-max anywhere from 9800 to 10,500. You are also talking about a motor that is 200cc a hole, not 265cc.
09-09-2008 5:31 PM In reply to
Offline SUPERTUNER
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Joined on 08-01-2005
Waterbury, Connecticut
Posts 1,320

Re: Rotax pro stock motor ?

 PS4 wrote:

On a 809 rotax motor that runs on ice and asphault,  which would be better?  1. A low reving motor(9000-9200rpm) that makes alot of torque   or a high reving motor (10,600-10,800rpm) that makes alot of hp?

Torque gets you going the first 5 feet. After that HP takes over. I would take a higher revving engine versus a torque monster. But what do I know?

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09-09-2008 9:15 PM In reply to
Offline 1000cc
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Joined on 09-04-2005
Posts 686

Re: Rotax pro stock motor ?

Freddie knows a lot..... but I would have guessed you would pick the lower rpm motor due to the inefficiencies of current cvt powertrains and the inability to manage all the belt issues.In a perfect world where clutches can effectively handle and transfer the power, I think the screamers rule.You see a lot of big motors out there try to run 800 gears and they spin, slip the belt and don't mph.Put a lot of torque in the motor down below, let the clutches work, and run it through the traps on the other end still gaining and you have a winner.
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09-09-2008 9:37 PM In reply to
Offline ProstockBenji
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Joined on 08-10-2005
Leamington, Ontario
Posts 351

Re: Rotax pro stock motor ?