Diesel-Chapter 6 Basic Engine Terminology and Operating Principles

compression ratio

A comparison between cylinder volume and clearance volume

horsepower (hp)

A measure of engine power, which is function of both torque and engine speed

two-stroke engine

An engine that uses an operating cycle that is completed using two piston strokes and one crank rotation

reciprocating engine

An engine that uses pistons moving up and down in a cylinder. A crankshaft converts the up-and-down motion into rotational movement

crankpin

The crankshaft journal which attaches the connecting rod to the crankshaft

peak torque

The engine speed where cylinder pressures are highest

cylinder block

The largest structure of an engine which encloses the cylinders and provides a rigid frame to support the cylinders or cylinder liners, crankshaft,oil and coolant passages, and in many engines the camshaft

valve overlap

The number of degrees of crankshaft rotation when both the intake and exhaust valves are open.

rated horsepower

The power output of an engine measured at the maximum engine speed

total cylinder displacement

The volume of all of the cylinders in an engine

combustion

a chemical reaction between fuel and oxygen that releases heat

torque

a measurement of rotational force, or twisting force, transmitted from the crankshaft to the flywheel

supercharged

an engine that pressurizes the air intake system to charge the cylinders with air

naturally aspirated

an engine that uses only atmospheric pressure and not pressurized air to charge the cylinders with air

idle

an engine's minimum operational speed

crankshaft

the component that converts the reciprocating action of the pistons to a rotational movement and revolves inside the crankcase portion of the engine block

main bearing journals

the crankshaft surfaces located along the crankshaft centerline supported by the main bearing caps

bore

the diameter of a cylinder

stroke

the distance traveled by the piston from the top to the bottom of the cylinder

clearance volume

the space remaining in a cylinder when the piston is at top dead center