The 9Ea was an air-cooled nine-cylinder radial with a 2:1 Farman reduction gear, 115 mm (4.528″) bore, 120 mm (4.724″) stroke, 11.218 l (684.6 in³) displacement and 5.75:1 compression ratio that was rated 250 hp at 2,600 rpm and capable of 280 hp at 2,700 rpm. Dry weight was 583 lb, or 2.33 lb/hp. Fuel consumption was 0.5 lb/hp/hr and oil consumption was 0.033 lb/hp/hr. Outside diameter was 42″ and length was 46″.

The 9Ea cylinders used steel barrels with integrally turned cooling fins that were screwed into cast aluminum alloy heads. Two inclined valves were operated by fully enclosed push rods and rocker arms driven by a cam ring at the engine front. A full-floating piston pin, two compression rings and two scraper rings were fitted to each aluminum piston. The two-piece forged steel crankshaft included a crankpin integral with the front section. The master connecting rod big end was fitted a floating bushing. The four-section crankcase inner sections were joined in the cylinder plane. The forward inner section housed the timing gears and distributors, and the rear section contained a mixture distribution fan driven at four times crankshaft speed. The nose section enclosed the propeller reduction gears, and the rear cover supported the oil pumps, generator and starter. The mixture was supplied by a Claudel carburetor, and the ignition by battery and coil. Lubrication was a force-fed dry-sump type using gear pumps; oil was scavenged from both crankcase ends.

The 9Eb, introduced in 1929, had a 115 mm (4.528″) bore, 135 mm (5.315″) stroke, 12.62 l (770.1 in³) displacement and 5.4:1 compression ratio. It was rated 250 hp at 2,150 rpm and 270 hp at 2,200 rpm. Dry weight was 550 lb. The mixture was furnished by a Stromberg carburetor, and dual ignition by Ducellier magnetos. Fuel consumption was 0.53 lb/hp/hr and oil consumption 0.0265 lb/hp/hr. The 9Eb diameter was 41.76″ and its length was 47.28″. Farman continued to improve the 9Eb and produced other 9E models through the 1930s.