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Comprehensive Component

Any component, other than a main monitor, that has any effect on vehicle emissions

Comprehensive Components

Any component, other than a major monitor, that has any effect on vehicle emissions.

Compressed Natural Gas

A gas, primarily methane, used as a motor fuel.

Compressibility

The ability of a gasket to conform to surface irregularities "soft" gaskets are more compensable than "hard" gaskets.

Compression

1. The process of squeezing a vapor (gas) into a smaller space. 2. The upward stroke of a piston that compresses the fuel/air mixture into the combustion chamber prior to ignition

Compression Braking

The slowing of a vehicle utilizing a diesel engine, such as that provided by a Jake brake. It is a misnomer that a gasoline engine will slow the vehicle by compression braking; actually, vacuum causes the braking effect.

Compression Gauge

A gauge used in the spark plug hole of the cylinder head to measure cylinder compression pressure

Compression Height

A distance, as measured from the crown of the piston to the center of the wrist pin.

Compression Ignition

The operating system of a diesel engine, where heated air is used to ignite the fuel.

Compression Intake Valve

A term used for compression valve or intake valve.

Compression Pressure

The highest pressure developed during the compression stroke in an engine, as checked with a compression gauge.

Compression Ratio

Each engine has a specific compression ratio that refers to how much the piston compresses the air and fuel mixture in the combustion chamber during the combustion cycle. If a particular engine has too little compression (or too low a compression ratio), it will not produce optimum power. It it has too much compression, it will suffer from preignition and/or detonation (commonly referred to as pinging), which can cause severe engine damage. The ratio literally refers to the difference between the volume of the cylinder when the piston is at bottom dead center and the volume of the cylinder when the piston is at top dead center.

Compression Ratio (CR)

1.A measurement of how much the air/fuel mixture is compressed inside an engine cylinder. If compressed to 1/10 of its original volume, the compression ratio is 10 to 1. 2. The ratio of the volume in the engine cylinder with the piston at bottom dead center compared (BDC) to the volume at top dead center (TDC)

Compression Ring

A piston ring that seals pressure during the compression and power strokes. There are usually two compression rings per piston.

Compression Seal

A metal seal found in a direct fuel-injection system, to resist compression pressures.

Compression Stroke

The movement of the piston from BDC to TDC, immediately after the intake stroke.

Compression Testing

A test of the engine compression through the spark plug hole to determine if the cylinder is sealing adequately

Compression Valve

A calibrated valve, located at the base of the shock absorber, providing variable resistance to fluid flow during compression.

Compression-loaded Ball Joint

A suspension ball joint, mounted above and resting on the knuckle, so the vehicle weight forces the bal into the joint.

Compressive Strength

The maximum compressive stress that a material can withstand without significant plastic deformation or fracture.