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rotary engines

Posted by lcausey383 (My Page) on
Sat, Oct 7, 06 at 16:37

does any one know if there where ever any rotary engine mowers produced? thanks


Follow-Up Postings:

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RE: rotary engines

Probably not. Possibly too expensive. NSU made motorcycles with the Wankel engine. It may just be a case of a technology which is not needed on the lawnmower level. Heck, we're still arguing over Honda's OHC engine and whether it represents unnecessary technology for a mower.


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RE: rotary engines

Wankels are way, way simpler than a OHC design, though. They have only two moving parts that I can think of: the rotor and crankshaft. In fact, there has been a Wankel model airplane engine that was in production for many years by OS (I assume it's no longer made, but I don't know). I do think the the machining process of the chamber is rather difficult, though - making that trochoid shape is nowhere near as simple as boring a perfect cylinder. Aside from poor fuel consumption and emissions, the biggest issue with Wankels is probably noise. They have no valves and are so inefficient that they are still burning the mixture as it exits the engine. Therefore, they are very loud and they require very heavy exhaust systems to hold up under the extreme heat. So these days, I'm not sure that problem could be overcome cost-effectively. Furthermore, I wonder if they could be made to pass EPA requirements cost-effectively. Probably not.


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RE: rotary engines

  • Posted by canguy British Columbia (My Page) on
    Sat, Oct 7, 06 at 22:58

Apparently Dolmar made a Wankel chainsaw that never saw production. Probably too expensive as saxman suggests but would have been interesting.


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RE: rotary engines

Sachs made a Wankel engine lawnmower in 1972. We sold them at the dealer I worked for. They were air cooled, very smooth, and powerful. Suzuki made RE5 Wankel engine motorcycle for 2 years in the mid 70s. I owned one for several years. Mazda still makes the Wankel engine equipped 232hp RX-8 sports car.


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RE: rotary engines

  • Posted by canguy British Columbia (My Page) on
    Sun, Oct 8, 06 at 11:07

I rode an RE5 once and it was scary fast for its time. Redlined VERY quickly.


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RE: rotary engines

There is a Sachs rotary mower engine on E-BAY. BUY IT NOW for $200.00.


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RE: rotary engines

I recently aquired a rotary powered lawnmower in mint condition. It is a "21" Grass Cat" marketed or manufactured by Arctic Enterprises, Inc. The owners manual I have says it was printed in February,1973. The engine is a KM 3,Ser.#7205719, Fichtel&Sachs, Schweinfurt, Germany. "Wankel Rotary" is tagged on the mower along with the words "System NSU". So, the obvious answer to the original message is yes. If you want further info on this machine, let me know as it is definitly the first one I have ever seen.


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RE: rotary engines

I worked for Rotary Engines (1981) LTd in NZ for 6 years. The KM3 lawnmower was a disaster in NZ as the coir fibre air cleaner element allowed the pumice dust through and wore out the side plates in a matter of hours. We imported 60 Wankel chainsaws which were great except for the weight factor. NZ Forestry would not use them because of that, but used the KM48 10 hp on their portable fire pumps. We also put many into yachts as auxiliary motors. When Sachs sold out to Norton, I personally built up over 100 KM48's from spare parts for sale to Forestry. The KM 914 20 hp were used on portable water blasting units (2500 psi) and I also built many of them from parts. The Wankel industrial engines were easy to work on and the power to weight factor was great. The KM3 had a lot of coil problems and I spent many hours pulling on the pull cords!


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RE: rotary engines

Oh Great.

Thanks a whole lot, gang.

Now I have that 1970's Mazda ad stuck in my head again.

"Piston engine goes Boing boing boing boing!....
but the Mazda goes mmmmmmmmmmmmmmmmmmm"

Here is a link that might be useful: Might as well stick it in your head too!


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RE: rotary engines

to ysinc2007 if you want to sell your lawn mower email me at sssales@cvtel.net thanks


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RE: rotary engines

Hi!: the french garden machine co Outils Wolf produced the Rotondor, a rotary engine equiped lawnmower with a Sachs engine that laid on its side down, and it seems that the engine had no side seals in the bottom side in order to cut production costs. YANMAR Diesel of Japan built some rotary engine chain saws. Salut + JGA


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RE: rotary engines

A rotary engine lawnmower would be cool to have because it's interesting,and has the least moving parts;but I wouldn't want it to use everyday;were would you get parts for it,when the time comes?Plus there might be issues,such as carbon build-up from running at such a constant RPM,etc.....Technology is great, in the right place;OHC on a lawn mower is useless,(Especially if it has a belt!!)because a lawnmower runs at nearly constant speed,and OHC is only an advantage for acceleration,and high RPM....the exact opposite of a lawnmower.....


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RE: rotary engines

ysinc2007 - Does your Grass Cat still have the original ignition coil? If not, what are you using as a substitute? (I bought one of these a couple years ago, with what I'm told is a bad coil, which I understand to be a common problem with these engines.)


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RE: rotary engines

I always thought the Wankel was an answer in search of a problem,the same thing can be said for a OHC engine on a mower. I would be happy to put money on my well used Lawn Boy 7024 out lasting a brand new Wankel powered mower.


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