Hello ODK History Lovers
The Briggs & Stratton Sonoduct Series of engines were revolutionary when
introduced in 1960. They were a commercial flop ... in the vain of the Ford
Edsel and the Bristol Brabazon. It wasn't a fault of the design.

Perhaps too radical for the day, the design would prove its worth decades
later, and was a design inspiration to the Victa Power Torque engine. The
radical feature was the moving of the ignition flywheel and recoil starter
to the under-deck.

There is scarce information on these engines. There is certainly miss-
information on them. Some comments I have read say they were designed as
a cheaper engine, or they were designed for a lower centre of gravity.
That is nonsense.

The name gives it away. 'Sonic' relates to sound. This was an early attempt
to make a quieter engine. A spin-off advantage from this was in styling potential.
Lawnmower makers could make a lower silhouette rotary lawnmower.

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TO BE CONTINUED ...