Dictionary of Automotive Terms Abbreviations

DICTIONARY OF AUTOMOTIVE TERMS - "Sq"

Squab panel: A panel supporting the rear seat squabs, separating the passenger compartment from the luggage space

Square engine: An engine in which the Bore diameter and the length of the stroke are the same.

Also See
Over square engine
Under square engine

Square-four engine: A four cylinder engine in which each cylinder axis forms one corner of a square. This represents a way of doubling parallel twin cylinders to make a four cylinder unit, with two separate parallel crankshafts connected by gears or chain. This arrangement allows the engine width to be kept to that of a twin cylinder unit with only a small increase in length, thus providing the advantages of an in-line four without the problem of width. Applied in four-stroke and two-stroke motorcycles; in two-strokes mainly to permit rotary valve induction

Square jetting: Same size jetting in all four holes or same size in primary barrels with a difference same size in the secondaries

Square key: A small bar of any length but its height and width are the same.

Square tapered bottom bracket: The industry standard Bottom bracket shape until Shimano developed the Splined bottom bracket. Square tapered refers to the shape of the ends of the bottom bracket spindle.

Squat: The action of the rear end of the vehicle to point downward during hard Acceleration. Squat is caused by a load transfer from the front to the Rear suspension. Also see Anti-squat system.

Squeak: An expression used particularly with Two-stroke engines where the Pistons have run without sufficient lubrication. It is caused by a poor Injection system or a pre-mix that is too lean (not enough oil in the Gasoline).

Squid: Someone who rides a sportbike on the street as if he were on a racetrack.

Squirrel cage: Fan which has blades parallel to fan axis and moves air at right angles or perpendicular to fan axis.

Squish: An area in the Combustion chamber of some engines where the Piston squishes or squeezes part of the Fuel-air mixture at the end of the Compression stroke. As the piston approaches Top dead center, the mixture is pushed out of the squish area and this promotes turbulence, further mixing of the Fuel-air mixture and more efficient Combustion.

Squish band: A narrow section of a combustion chamber in which the fuel charge is more compressed by the piston than in the rest of the chamber; designed to help direct the flow of the fresh charge and to improve scavenging

Squish combustion chamber: Click image to supersize
Squish combustion chamber

The volume in the cylinder above the piston that can be a variation on almost any of the standard forms of combustion chambers. The squish area that gives it its name is the flat surface of the cylinder head that almost contacts the piston crown. When the piston rises on the compression stroke, it squishes, or sqirts, the gas from this area into the combustion chamber with a swirling motion. This mixes the air-fuel mixture thoroughly for more complete vaporization and combustion. At the same time, the mixture is cooled as it swirls past the chamber walls, which are kept relatively cool by the water passages.

Also See
Hemispherical combustion chamber
Bathtub combustion chamber
Wedge combustion chamber
Piston-crown combustion chamber

Squish zone: A narrow section of a combustion chamber in which the fuel charge is more compressed by the piston than in the rest of the chamber; designed to help direct the flow of the fresh charge and to improve scavenging