Capri Definitions

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z



    Paint Cleaning Clay

Polishing is the traditional method of removing paint contamination. Recently, a new consumer product, called paint cleaning clay, has emerged as a better way to clean paint. Paint cleaning clay is a soft, pliable bar of abrasives suspended in a clay. Used with a spray lubricant, 3-4 light passes over your paint is all that's needed to make it perfectly smooth.

    Pressure Washer

Water applier under pressure is a good cleaner. Some detailers use high pressure washers to clean engines and undercarriages. Be careful. Too much pressure will damage paint, remove trim, and penetrate under coatings or delicate electrical connections.

    Panhard Rod

Long lateral link that provides lateral location of a rigid axle. It usually sits roughly parallel to the axle, with one end attached to the body and the other attached to the axle

    Passenger Vehicle

Four wheeled motor vehicle that also includes mini-vans and sport utility vehicles.


A combustion chamber whose upper surface resembles a shallow peaked roof. Usually used with four valves per cylinder.

    Personal Transport (PT)

The initials used by Chrysler for the PT Cruiser. PT stands for Personal Transporter.


The phaeton term was often applied to convertibles built in the1930's and earlier. A phaeton is a sleekly styled car (usually 2-door) with a convertible top. The conventional body has 4 doors with convertible top and side curtains rather than roll-up windows. The four-seater was called a double phaeton, and the six- or seven- seater a triple phaeton.


A small diameter gear with a small number of teeth designed to mesh with a much larger gear wheel or a toothed rod (rack). Used in rack-and-pinion steering and for speed reduction with an increase in power.


A partly hollow, cylindrical metal engine part that is closed at one end and fits into the engine cylinder. Connected to the crankshaft via the connecting rod and usually fitted with rings to seal it in the cylinder.


The rotation of a car about a horizontal axis, which causes its nose or tail to bob up and down. Dive and squat are pitching motions.

    Planetary Gears

A gearset in which all of the gears are in one plane, grouped around each other like the planets around the sun. The central gear is called the ""sun gear."" In mesh with it is a circular grouping of gears, called ""planet gears,"" mounted on a rotating carrier. The planet gears also engage teeth on the inner periphery of the ""ring gear."" By holding any one of the three gear elements motionless, different ratios can be produced between the other two. Planetary gearsets are common in automatic transmissions.

    Plastic Moulding

A process that converts organic-based materials, by means of a general-purpose press and purpose-built tooling under controlled heat and pressure, and injects the hot material into a die cavity shaped in the final form of the intended part.

    Plenum Chamber

A chamber, located between the throttle body and the runners of an intake manifold, used to distribute the intake charge evenly and to enhance engine breathing.

    Pneumatic Tire

A circular tube of rubber or synthetic rubber and fabric, and sometimes also steel, attached to the rim of the car's wheel, having resilience due to its containing air under pressure.

    Polar Moment of Inertia

The resistance of an object to rotational acceleration. When the mass of an object is distributed far from its axis of rotation, the object is said to have a high polar moment of inertia. When the mass distribution is close to the axis of rotation, it has a low polar moment of inertia. A mid-engined car has most of its mass within its wheelbase, contributing to a low polar moment of inertia, which, in turn, improves cornering turn-in.


A specially formulated blend of components designed to remove minor paint surface imperfections, such as fine scratches, light oxidation, water spots, and swirl marks left by the use of rubbing compounds. Polishes may or may not contain waxes or silicones.

    Port Fuel Injection

A type of fuel injection with at least one injector mounted in the intake port(s) of each cylinder. Usually the injector is mounted on the air intake manifold close to the port. Port fuel injection improves fuel distribution and allows greater flexibility in intake-manifold design, which can contribute to improved engine breathing.

   Positive Displacement

If a charger is a positive displacement compressor, it simply means it displaces a certain amount of air per revolution, assuming that it is 100% efficient. Roots, vain and screws are all examples of positive displacement compressors. Centrifugal blowers rely on the inertia of the air to make boost, so the efficiency increases as rpm rises, therefore they are not positive displacement compressors.

    Pound Feet

The unit of measurement for torque. One pound-foot is equal to the twisting force produced when a one-pound force is applied to the end of a one-foot-long lever.

    Pounds per square inch (PSI)

The common unit of measurement for pressure. Normal atmospheric pressure at sea level is 14.7 psi.


The rate at which work is performed. Power is proportional to torque and rpm and is measured in horsepower.

    Power Band

The subjectively defined rpm range over which an engine delivers a substantial fraction of its peak power. The power band usually extends from slightly below the engine's torque peak to slightly above its power peak


An engine and transmission combination.

    Production Engineering

Planning and control of the mechanical means of changing the shape, condition of materials toward greater effectiveness and value.


The aspect ratio of a tire.

    Progressive-Rate Spring

A spring with an increasing spring constant. For example, if the first inch of spring motion requires 100 pounds of force, the second inch would require more than an additional 100 pounds, and the third inch would require still more. Progressive-rate springs become stiffer as they are compressed, unlike single-rate springs, which have a fixed spring rate.


The test model of a new car design that is intended to be produced in quantity.


A slang term for under steer.


A metal rod that transmits the motion of the camshaft to the valve actuators. Pushrods are used by non-overhead cam engines to open and close valves. Pushrod A metal rod connecting the valve lifter or camshaft with the valve rocker arm on overhead-valve engines. Pushrod A general term for any rod that transfers force in compression. In a valvetrain, pushrods are used to transfer reciprocating motion from the cam followers to a more distant part of a valvetrain, typically the rocker arms.

Back To Top