multi-cylinder engine
reciprocating internal combustion engine with multiple cylinders
radial engine
reciprocating engine with cylinders arranged radially from a single crankshaft
flat-twin
horizontally-opposed two-cylinder piston engine
inline engine
reciprocating engine arranged with cylinders in banks aligned with the crankshaft
W engine
reciprocating engine with three banks of cylinders
V engine
internal combustion engine with two banks of cylinders at an angle resembling a 'V'
straight engine
engine configuration
rotary engine
internal combustion engine with cylinders rotating around a stationary crankshaft
flat engine
engine configuration with horizontally opposed cylinders, usually a flat-V or boxer configuration
H engine
inline engine with four banks driving two crankshafts
Y engine
internal combustion engine with three banks of cylinders at an angle resembling a 'Y'