Brett & Tiana Campbell wrote:

Hi all,
I recently picked up a Sachs air-cooled (single-rotor) snowmobile engine originally from an
early-'70's Arctic Cat snowmobile. The price was right, and curiosity got the better of me.
Interesting contraption--- no inter-housing seals because it's air-cooled, and the internal
components (ie: rotor and thrust bearings) are lubed and cooled by the 40:1 pre-mix air/fuel
mixture, which is routed through the center of the engine prior to entering the intake port. I
believe this method is referred to as "charge-cooled and lubricated," but correct me if I'm wrong.
The basic engine core sans external components weighs approximately 35 lbs, and measures about 13
inches in diameter x about 6 inches thick, with a 12-inch long e-shaft. BTW, most of the diameter
is cooling fins--- the rotor chamber oval is only about 7 inches x 5 inches, with a rotor width of
just under 3 inches. Only one spark plug is used, and the rotor uses no oil-control o-rings, only
conventional side, corner, and (single-piece) apex seals. Both end housings and the rotor housing
are aluminum (even the wear surface of the rotor housing is aluminum, not plated), with an iron
rotor and solid-steel e-shaft. All bearings are non-tapered roller type, including those inside
the rotor where it rides on the e-shaft eccentric. I'm not sure if the apex seals are carbon
steel, cast iron, or some other steel material. Beyond that I don't have any other specs on this
engine.
Do any of you know what the displacement, rated horsepower, and torque of this engine is? Also
does anybody have an idea as to the proper running clearances and wear tolerances of this engine?
Just wondering, because I'm thinking it just might be suitable as a powerplant for a basic
ultralight, if and when I ever decide to build or purchase one.

Displacement can be calculated knowing the housing long axis, short axis and width. Rolf

 
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