MAC 10 Sachs Wankel

1) OMC, (Evinrude/Johnson), built a handful of massive 4 rotor engines that were used by their outboard racing team in the early 1970's and then retired.

2) The April 1973 edition of the OUTBOARDER, magazine of the AOMCI, indicates that Yanmar (the inboard engine & tractor folks) made an approximately 20hp Wankel, however I do not know of anybody who has seen or used one.

3) Possibly the most numerous example of a Wankel powered outboard motor is the MAC-10 featured here. (Be sure to scroll down for the full story and photos of the powerhead.)

The Mac-10 Sachs Wankel outboard was available from the late 1960’s through the early 70’s. It was a joint German & Italian effort. Fichtel & Sachs in Germany provided the power; a 160 cm3, single rotor, air cooled engine developing between 8 hp and 10.5 hp (The horsepower varies depending on what F&S manual you look at). An Italian organization believed to be named Moto Attrezzi Co. (hence MAC) made the the leg, cowl and other parts and also marketed the motors.

Sachs designed the engine to be used as power for rototillers, pumps, generators, lawnmowers, etc, etc.. much as B&S, Tecumseh, Kohler and others do in this country. Despite extensive testing, (and the best efforts of Sachs' sales & marketing departments), - it is not believed that these small Wankel motors were very popular. Larger displacement versions of the F&S rotary combustion engines were available in the USA and Canada on snowmobiles. There is very little information regarding the Italian company (Moto Attrezzi) that assembled and sold the motors – they did not even include their name or corporate information in the instruction manual!

The Mac 10 has a simple Bing carb and a Bosch flywheel magneto – both are very similar to what was used on European mopeds and small motorcycles back in the 60’s & 70's. The magneto has a lighting coil and there is a plug on the front of the motor supplying 6 volts and 17 watts for your running lights. The MAC runs on 50:1 oil/gas mix and, since it is air-cooled, it is preferable to use a quality chain saw or motorcycle oil on this motor rather than TCW-3. (We run it at 40:1 for added protection) Since several people have asked; my preferred oil for air-cooled 2-cycle engines is Golden Spectro Two-Cycle Pre-Mix Blend. However this oil is not easily found these days - I've also had good success with Stihl 2-cycle oil, the same stuff I run in my chainsaws. It is available at any Stihl dealer.

As a visitor to this website pointed out, even though you mix the gas an oil together for lubrication the rotor and seals, this motor is not a 2-stroke. Wankels are unique in that they have induction, compression, combustion and exhaust cycles but are also not 4-strokes since they do not reciprocate. A happy compromise would be to describe this motor as a 4-cycle burning pre-mixed fuel and oil for lubrication.

The leg of the outboard is equipped with water cooling via forced water traveling up a tube aft of the propeller. (Obviously it only works in forwards) The motor has a standard F/N/R shift on the starboard side, pull start/recoil on the top front of the cover and a typical tiller & twist grip off the port/front side of the engine. Engine speed is achieved by twisting the tiller grip in the conventional manner but greater throttle is provided through the carburetor only, the magneto timing is fixed. The flywheel is finned to provide a forced down draft of air to cool off the powerhead.

The motors are smooth, reasonably quiet (for an air cooled outboard) and sound like nothing else on the water! (Kind of a buzzing/whirring sound) On the down side; they are heavy, (almost 80lbs), IMHO of questionable styling, use a lot of fuel and are not very robust in overall design (Things can and do break off) It does not idle well and constantly "hunts" with a variance of about +/- 75 RPM. (Of course it was designed to move - not idle!) Based on personal experience, we would peg the Mac10 at about 7.5 to 8hp relative to any 50’s or 60’s 10hp Johnson or Evinrude.

For whatever reason, a good number of references to Mac 10’s show up in posts on the snowmobile and tractor boards I have looked at. I have seen several for sale on ebay and know of about 20 members in the AOMCI that have one. Parts availability is tough; some can be gleaned from snowmobiles and motorbikes but everything else is very scarce.

While not exactly an antique, the Mac 10’s are a fully functional outboard and a definite oddity!

                  

MAC 10 Engine detail front & rear - Sachs name visible on air deflector.
(Click on an image for a larger view)

Photo showing the Mac 10 rotor, seals and seal springs	Modern Mazda RX-8 rotor and Mac 10 rotor - 40 years difference but they sure look similar!

Here is a short video from the summer of 2013 of my son Harry running a 1972 Mac 10 that we put together from two parts motors. (Thanks to Jim M. and Jerry H. for them!) There is not really any difference between it and the earlier 1969 version in the photos above, the cowl doesn't have the "Fireball & blue smoke" emblems on the side, just simple black & white decals - mechanically they are identical. The sound and "feel" of the motor doesn't come through on this video, I guess that's something that needs to be experienced in person!

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