Pivotal Engineering Ltd has made a series of engines that cannot be said to be precisely piston, although they have a crankshaft and connecting rods.

“Pivotal system”

-An articulated plate oscillates on a pivot point (Pivotal) making curved strokes, which do not affect the alternative system of connecting rods and crankshaft. In addition, this plate is cooled by water inside.

"Light range"

-Pivotal has made 264 cc engines running at 7,000 rpm. and 400 cc engines for motorcycles running at 11,500 rpm.

-The 1 liter (1100 cc) was presented at Oshkosh-EAA in 2002. It ran on Diesel and JP5. It delivered 120 HP.

-There is also the 1050 model that has been made for aviation, with PSRU gear and Airmaster propeller.

“Model 1050”

-The 2 liters (2.1 lts), had four horizontally-opposed chambers (note that “opposed cylinders” has not been said).

“Three views of the 2.1 ltr engine”