F. Lefevre was a sports car builder under the “La Perle” brand until he decided to build his aviation engine.

-He named it D-4 and it was a horizontally-opposed twin-cylinder giving 33 hp at 3,750 rpm. It was the year 1936.

-The D-4 displaced 760 cc and had a 2 to 1 reduction box, so when the crankshaft rotated at 3,750 rpm, the propeller did so at half revs.

“Lefevre, 33 CV”

-Tests were carried out on a "Pou-du-Ciel". But it was also installed on other aircraft such as the Microplan LT-51.

“Microplan with Lefevre”

-Below, an exploded view in which we see the crankshaft, pistons and connecting rods as well as the crankshaft gear, smaller than that of the propeller shaft.

“Lefevre engine parts”

-According to an article about this engine builder from Villeneuve-Loubet, in the Maritime Alps, who is also very fond of aviation, he used gears from a truck for the gearbox and the connecting rods were from the six-cylinder "La Perle" engine.

-The valve lifters were from Citroën. He built the engine with the machinery of his workshop.

From appendix 12: Below we show the boxer engine, partly assembled and partly exploded.

"Illustration on the engine details"

-This engine gave 22 CV and was geared. It was built by Lefevre-Villeneuve-Loubet. The bore was 75 mm and the stroke 85 mm.