Rotary Engine??

[ProfessorRog]

I didn't know these came on bikes

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2420140012&category=6027

[70 Cam Guy]

see if you can shoehorn a 2 rotor in there and see how fast it will go  
:lol:

not a fan of that giant radiator

[Black Snowman]

You've found the infamus RE5! Over-weigh, under powered, and a two stroke if I remember correctly. There's a short blurb about it in the intro to the Haynes GS500E manual. Plagued with technical problems they never gained ground. I here 1 other manufacturer tried a rotory. Kawasaki maybe. But it didn't take off either. With modern materials I would think it would be much more practical to attempt now and I would think that the properties of a rotoary would be almost ideal for a bike.

Extremely high HP to weight ratio, compact, reliably rev to very high RPM, overheating problems . . . well maybe not that one

[KevinC]

You've never heard of the famous Norton rotary? It won quite a few big races in the early '90s, and was used as a police bike.

http://www.monito.com/wankel/norton.html
http://www.jpsnorton.com/history.asp

Wankel rotaries are probably dead as a road going engine. The long, flat combustion chamber has too much surface area for decent burning, and the fuel consumption and emmisions are poor as a consequence.

[Black Snowman]

No I hadn't heard but I wasn't following motorcycling at all until the new millenium otherwise I'm sure I would have known about it

You're right about the combustion chamber being less than ideal. Oh well, if you want an alternative motor you can always grab that Y2k turbine bike on e-bay.

[wingbolt]

Mazda is coming out with the RX-8, a new sports car using a re-designed normally aspirated 2 rotor rotary engine.
The new and refined rotary won International Engine of the Year award this year.  See http://www.mazdausa.com/MusaWeb/rx8/index.jsp

[Seth]

Wankel rotaries are probably dead as a road going engine. The long, flat combustion chamber has too much surface area for decent burning, and the fuel consumption and emmisions are poor as a consequence.

Check out the new Mazda Rx-8,  Long live the Wankel!

[glenn9171]

I have a friend that took a rotary engine out of an old Mazda truck, tweaked it and put it into an old Ford Courier.  Talk about a sleeper.  Stock tires and plain white steel rims.  Smoked all comers.  Mustang Cobras, Ram-air Firbirds, and took $1000 off of a local boy with a souped up Dakota R/T. :nana:

Revved to 14K in every gear.  It would do 140 mph easily, but at that point, the front end would not steer from the air lifting the front end.

[wingbolt]

I think that's the Mazda 20B rotary, a three rotor 2 liter engine.  Smooth as a turbine, just much cheaper.

[Black Snowman]

My brother made a kit car built on a VW Bug chassis and put a RX-7 motor in it. He forgot to upgrade the clutch and tranny so when you stomped it the clutch would slip. Still do almost 90 in 2nd gear though

[Rich500]

I dont think KevinC understands the rotary. It is brilliant. Yes its tempermental, but know, with the renisis 1.3l rotary in the RX-8, they have cured all the problems. It is lacking in the torque department, but whatever. a 1.3l wankel weighs 100lbs less at least than most aluminum V-6 engines in many other sports cars a la Infiniti G35. They have gone to a side port valve system which helped cure the emmisions problem, also helped out fuel economy. People dont understand that just because the engine has a 1.3l displacment, its doesnt mean it can achieve stellar fuel economy. Remeber how fast it is revving. Revs kill fuel consumption, not amount of cylinders, or displacment to a point. I drive my 5.7l LT1 Camaro and can manage 25 mpg plus on the higway if i keep the revs down. Same principal in a rotary. I think a 500cc wankel rotary in a street bike would be incredible. You could theoretically achieve 96hp easily with 61ft/lb torque. The weight could potentially be much less than a comparable 600-750 cc engine. Can you imagine the possibilities?!

[Rich500]

Oh yah! Hey KevinC, want to go riding sometime? we can get a bunch of us alberta guys togehter. im in calgary, what about you?

[neilc]

Rotary engines are very interesting.
http://travel.howstuffworks.com/rotary-engine.htm

This page has a great little animation of how the engine works.
http://travel.howstuffworks.com/rotary-engine4.htm
I never really understood it until I saw that animation go.

As far as I know, there are still problems with these engines, such as fuel efficiency and endurance - the seals between the chambers wear down and there isn't as much compression as in a normal engine.

That howstuffworks site has some good information about it.

[glenn9171]

I think that's the Mazda 20B rotary, a three rotor 2 liter engine.  Smooth as a turbine, just much cheaper.

Correct.    20B.  That's what it was.  He had a Holley 4-barrel on it with a K&N filter.  Good thing the Gates fan belt had a lifetime warranty.  He went through about 3 or 4 per month.  They don't handle constant runs to 14K RPM as well as one might think.

[KevinC]

I understand the rotary well enough. Yes, you can make a few of them still, and meet the fleet average fuel consumption requirements if you sell enough other effcient piston cars. And you can meet the emmsions with a big catalytic converter. But it is expensive, and you can't build many or your fleet fuel consumption goes to hell.

The basic wankel design has a bad combustion chamber shape. Yes, they make great, smooth power for their size and weight. But they eat a lot of fuel doing it, and the emmisions are always bad.

[DavidGS]

What would you like to know about the rotary? I have 4 RX7's and have built many engines for them.

[KevinC]

Revs kill fuel consumption, not amount of cylinders, or displacment to a point. I drive my 5.7l LT1 Camaro and can manage 25 mpg plus on the higway if i keep the revs down. Same principal in a rotary.

Revs don't kill fuel consumption, and it is not a simple matter of the number of cylinders. Only in North America would 25 mpg on the highway be even vaguely considered acceptable fuel consumption. The torque/rpm characteristics of the rotary, which will always be very different than a 5.7 L V8, means you won't be running it at low rpm even cruising on the highway.

I think a 500cc wankel rotary in a street bike would be incredible. You could theoretically achieve 96hp easily with 61ft/lb torque. The weight could potentially be much less than a comparable 600-750 cc engine. Can you imagine the possibilities?!

The Norton 500 cc wankel rotary that was produced in the '80s was basically at those numbers (see links above). There are many other issues, not the least of which is most people won't buy a rotary because of it's past probelms.

A 500cc rotary is sort of comparable to a 1000 cc piston engine. Those numbers aren't even close to the GSXR 1000. Potentially the weight might be lower, but more likely a huge catalytic converter would be required in a lot of countries. And the fuel mileage and tractability of the rotary wouldn't approach that of the 1000cc piston engine.

[Rich500]

Good points KevinC. Very good in fact. You have redeemed yourself. Just kidding. Anyway, you sure are right that 25 mpg would only be considerded decent in North America. Its in credible how for granted many north Americans take their big V8 SUVs and such. In a few years you will be able to buy a Lincoln Navigator for pennys if our gas prices go on the rise!

[KevinC]

Oh yah! Hey KevinC, want to go riding sometime? we can get a bunch of us alberta guys togehter. im in calgary, what about you?

I don't have a street GS. I am riding to Dawson City, Yukon soon, on my '82 BMW. Want to come?

Actually, I don't like riding in groups very much. I prefer exploring back roads by myself, or maybe one other rider.

Have fun though!

[DavidGS]

A 500cc rotary is sort of comparable to a 1000 cc piston engine. Those numbers aren't even close to the GSXR 1000. Potentially the weight might be lower, but more likely a huge catalytic converter would be required in a lot of countries. And the fuel mileage and tractability of the rotary wouldn't approach that of the 1000cc piston engine.

Actually, a 1.1L rotary CAN produce up to about 300hp N/A.