Manifold. A pipe with a number of inlets to, or outlets from, the
several cylinders of an engine.
Manometer. A U-shaped glass tube, partly filled with a liquid, water
or mercury, employed to measure pressure.
Mean effective pressure. The mean or average pressure which, acting
on lie piston, would do the same work as does the actual variable pressure
in the cylinder. Abbreviated mep.
Mechanical efficiency. The ratio of brake horsepower to indicated
horsepower.
Mechanical injection. Injection with the fuel-valve operated mechanically
from a cam. Sometimes, although wrongly, used to indicate airless injection
in general.
Motor. A mechanism doing work by means of a ready source of energy,
such as electric current, compressed air, or oil under pressure. Incorrectly
applied to the combustion engine in an automobile.
Muffler. A device used to diminish noise of the intake or exhaust.
Sometimes referred to as a silencer.