Wankel Engine

[Matthew Pieklik]

I see a MAC 10 Sachs Wankel rotary engine outboard motor for sale on Ebay. I believe Mazda also had the Wankel in the RX7 back in the day. What was the demise of the Wankel engine?

[Buccaneer]

I think I remember hearing they had a lot of problems with the rotor seals.
Emissions and gas mileage may have been another factor.

Prepare to be boarded!

[frankr]

OMC also spent a lot of money on R&D of the Wankel.

[GLEN DEUTSCH]

I have a Mac 10.
It is a screaming demon. Starts first pull. High pitched whine but not much louder than an old Evinrude/Johnson. Burns a lot of gas. Hard to get the speed adjusted right. The throtle control is a little jumpy. Ratio of response to twist is too high. Heavier than an OMC of comparable horsepower. Gearcase is exactly like OMC except that it is metric. Bearings can be replaced at McMasters. Carb is easy to clean and adjust. You can start test it in the shop because it is air cooled. Uses 50:1 mixture, but dont use TWC-3. Use chainsaw oil. I lucked out on the ignition. Did not need to touch that. Fun toy ,if you can get it cheap.Got mine for $25.00

Glen

[amuller]

I’d like to have one to play with.

Many big US companies put a lot of money into Wankel engines–OMC, Curtis-Wright, General Motors, others…. Some of the problems can be solved with engineering, like the tip seals, others are fundamental to the design. One is the high surface to volume ratio of the combustion chamber, leading to high heat loss and low thermal efficiency. Another is the need for total-loss lubrication, leading to high emissions.

I’m vaguely remembering that OMC made a Wankel snowmobile engine (??) but ended up not producing it. (??)

[Matthew Pieklik]

I passed on a Wankel engine at a garage sale. Guy said it was from a sled. Had an OMC coil attached. Kicking myself.

[Alan]

Thanks to Glen Deutsch for the excellent info!
i’ve wondered about those, having had, (and loved) a Mazda RX-7. Since there are very few internal moving parts spinning around, (like a crankshaft, rods, and pistons), they really do scream. I loved embarrassing Corvettes and Jaguars at stoplights. (Of course, embarrassing an early 80’s ‘Vette is not that tough!)
The apex seals at the tips of the rotors are a definite wear item.
The fuel economy is not great, and it put out plenty of emissions. More than its fair share, for a motor that displaced only like 1,400 CCs.
Excellent throttle response, and very wide power band.
Love the sound they make!
All in all, a great deal of fun.

• This reply was modified 3 years, 9 months ago by Alan.

[The Boat House]

A guy a work had an RX-7. He liked his as well.

[Author]

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