The Jacobs R-755 (company designation L-4) is a seven-cylinder, air-cooled, radial engine for aircraft manufactured in the United States by the Jacobs Aircraft Engine Company.

With a bore and stroke of 5.25 in × 5 in (133 mm × 127 mm) the displacement was 757 cu in (12.4 L), power ranged from 200 hp to 350 hp (150 kW - 260 kW).

The engine features steel cylinders with aluminum-alloy cylinder heads.

An R-755E variant was developed for use in helicopters.

Data from Jane's fighting aircraft of World War II,[4] Jane's all the World's Aircraft 1938[5] Comparable engines Related lists