DICTIONARY OF AUTOMOTIVE TERMS - "Sm"

SM

API SM category

An API designation of engine oil that provides improved oxidation resistance, improved deposite protection, better wear protection, and better low-temperature performance over the life of the oil than previous designated oils. Some SM oils may also meet the latest ILSAC specification and/or qualify as Energy Conserving. It replaces API Service Category SJ and SL.

Small bayonet cap

Bayonet

A 16mm diameter base of a light bulb used in automobile lighting.

Small-block engine

During the '60s and '70s, GM, Ford, and Chrysler made two types of V8 engines of the same displacement e.g., 350 cu. in. small-block and 350 cu. in. Big-block. The small-block engine was an enlarged smaller displacement engine (e.g., GM enlarged the 283 to 327 then to 350 by boring the cylinders). The big-block engine was a completely different basic engine size even though it displaced the same as the enlarged small-block engine. Thus, as vehicles grew smaller and more equipment was stuffed into the engine bay, the small-block engine was favored over its larger brother.

Small end

The top of a connecting rod, attached to the piston pin

Small end bearing

The smaller bearing of the two on a connecting rod and through which the piston is attached; usually fitted with a plain bearing or a needle-roller assembly

Small pickup truck

A pickup truck weighing under 4,500 lbs GVW.

SMC

Acronym for Sheet molding compound

SMEC

Acronym for Single Module Engine Controller (replaced with PCM)

Smell

See
Rotten-egg smell
Stink-bomb smell

SMMT

Acronym for Society of Motor Manufacturers and Traders

Smog

Fog made darker and heavier by chemical fumes and smoke. A fog-like layer, often brown in color, that hangs over many areas under certain atmospheric conditions. Smog, a contraction of the words smoke and fog, is compounded from smoke, moisture and numerous chemicals produced by Combustion (from power plants, automotive engines, etc.) and from natural and industrial processes. Formation of smog is aided by the presence of sunlight which reacts with many chemicals and Combustion products such as Hydrocarbons and oxides of nitrogen to form other more noxious Compounds.

Smoke

The visible product of combustion; a common problem with diesel cars when starting or pulling hard, caused by too much fuel (Black smoke) or oil (Blue smoke).

Smoke meter

An instrument which measures the density of exhaust smoke, especially in diesel engines

Smoke test

Test made to determine completeness of combustion.

Smokey on four legs

Trucker slang for a horse-mounted police as in "There's a smokey on four legs at the next corner."

SMPI

Acronym for sequential multi-point electronic fuel injection.

Smut

See
Sealing smut