Onan P218 and P220 Differences

Subtle Differences

• The Cummins-Onan P218 and P220 engines are almost identical in their general configuration but have subtle differences reflecting their different uses. The P218 was engineered for quiet, economical operation in recreational vehicle AC generators while the P220 was engineered for maximum power output in garden tractors and other yard equipment. To ensure quiet operation, the P218 typically is set to run at half the speed of the P220 and as a result puts out half the horsepower of the P220.

P218 Engine

• The Cummins-Onan P218 is a horizontally-opposed two-cylinder, L-head, four-cycle, air-cooled aluminum gasoline engine with cast iron sleeves producing 10.3 hp at 1,800 rpm from a 47.7 cubic inch displacement. This engine has a 7:1 compression ratio, a 3.25-inch bore and 2.87-inch stroke, and has a 1.5 qt. oil capacity (3 qts. with oil filter). It is an electric-start engine using a 12 volt starter motor engaging a flywheel ring gear, similar to automobile engine starting systems. This engine was used mainly in generator sets.

Two Generator Sets

• Onan offered the P218 engine on two different generator sets for installation in recreational vehicles, the 4,000-watt BGE Emerald and the 5,600-watt BGM Marquis. These generator sets feature a revolving-field generator having a rotor with two slip rings and brushes. The BGE Emerald generator set weighs 216 lbs., consumes 0.6 gallons of gas per hour and puts out 33.3 amps of 120-volt AC current at 1,800 rpm. The BGM Marquis set weighs 258 lbs., consumes 0.7 gallons of gas per hour and puts out 45.8 amps of 120-volt AC at 1,800 rpm.

P220 Engine

• The Cummins-Onan P220 engine also is a horizontally opposed gasoline two-cylinder, four-cycle, air-cooled, L-head aluminum engine with cast-iron sleeves, but it produces 20 hp at 3,600 rpm from its 47.7 cubic inch displacement. Like the P218, the P220 has a 7:1 compression ratio, 3.25-inch bore and 2.87-inch stroke. It has a 1.5 qt. oil capacity (3 qts. with filter). It has an electric start with a 12-volt starter motor engaging a flywheel ring gear. This engine was offered to other manufacturers as part of the Cummins-Onan Performer series and was bought by several different yard equipment makers for installation in their garden tractors and riding mowers.