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Back in 1969, Rupp used German-made Sachs engines in its sleds. Power ranged from 12 to 20 hp in three different size engines. Sachs had a 736cc that was used as a water pump or in utility service. It was large, but it had enough horsepower and a lot of torque that might work for snowmobiles. All snowmobile manufacturers were crying for bigger engines to make the sleds go faster.
I have a letter that was sent by Sachs to Trail-A-Sled (the makers of Scorpion snowmobiles) on July 30, 1968. It states that approximately 45 of the Sachs SA740 engines would be available around December 1968 if Trail-A-Sled wanted them.
It’s rumored that Sachs sent 30 engines to America, and that Rupp, Skiroule and Scorpion each received 10 of them. I heard that Polaris received one to try out. Alouette might have tried some out too. I think there was a picture taken of one with megaphones.
The Sachs SA740 is one large engine. I would guess it weighs 120-135 lbs. Each cast-iron cylinder weighs 15 lbs. without piston or head. It was designed with large axle blower fans on the front of the engine, and it used standard 368cc pistons that came with two rings, aluminum rods and massive crankshaft bearings.
When the Germans built engines, they were built to last. Power was around 35-40 hp. The intake came with an upside-down HR-size Tillotson carburetor on top and an HD-size carburetor under the HR. It had one manifold for both carburetors and both cylinders.
For the exhaust, Rupp just curved twin pipes out and then downward through the tunnel. With no muffler, it had a deep, loud sound. The SA740 was just too large and heavy for the power it put out, but back then bigger engines were “the best.” This engine came in the Rupp GTX 740, and it came with a speedometer that read 80mph. I still don’t know how many GTX 740 owners buried the speedometer needle. If you see one, look it over well. It’s a cool sled.