More details can be found at http://penngrovepower.org/mainexhibits/

The R4360 was a 28cylinder fourrow aircooled radial engine. Each row of seven aircooled cylinders possessed a slight angular offset from the previous, forming a semihelical arrangement to facilitate effective airflow cooling of the cylinder rows behind them, inspiring the engine's "corncob" nickname. A mechanical supercharger geared at 6.374:1 ratio to engine speed provided forced induction, while the propeller was geared at 0.375:1 so that the tips did not reach inefficient supersonic speeds.

The Wasp Major was maintenanceintensive. Improper starting technique could foul all 56 spark plugs, requiring hours to clean or replace.

Engine displacement was 4,362.50 cu in (71.489 L), hence the model designation. Initial models developed 3,000 hp (2,240 kW), and later models 3,500 hp, but one model delivered 4,300 hp (3200 kW) using two large turbochargers in addition to the supercharger. Engines weighed 3,482 to 3,870 lb (1,579 to 1,755 kg), giving a powertoweight ratio of 1.11 hp/lb (1.83 kW/kg).