The increase above atmospheric pressure produced inside the intake manifold by any supercharger. It is commonly measured in psi, inches of mercury, or bar.

The diameter of a gasoline or steam reciprocating engine cylinder. The displacement can be increased by increasing the diameter (reboring).

The front/rear distribution of a car's braking power. For the shortest stopping distance, brake bias should match the car's traction at each end during hard braking brake modulation: the process of varying pedal pressure to hold a car's brakes on the verge of lockup. Ideally, the brakes will unlock with only a slight reduction in the pressure needed to lock them. Typically, however, a considerable pressure reduction is required.

A device that uses engine vacuum or hydrualic pressure to multiply or boost the pedal effort of the driver while braking, thus adding more hydrualic pressure to the brakes for added stopping power.

A c-shaped device used with disc brakes. When a driver presses on the brake pedal, the caliper piston squeezes the brake pads against the rotor and causes the car to slow down or stop. Brake pads are mounted to calipers, which float next to the brake disc.

Drag is created when brake shoes or brake pads continually rub against a brake drum or disc. It can lead to break failure.

Brake drums are drum-shaped components which contain internal brake shoes, which expand and press against the drum, when the driver presses on the brake pedal, slowing or stopping the car. A type of braking system that utilizes a metal drum mounted on a wheel to form the outer shell of a brake. Drum brakes are usually mounted on rear wheels. Drum brakes are prone to fade, from heat buildup, which reduces their effectiveness.

A condition brought about by repeated brake applications, resulting in build-up of heat that cause a temporary reduction or fading of braking effectiveness.

A special type of hydraulic fluid designed specifically for brakes. Brake fluid transfers the motion of a driver stepping on a brake pedal directly to operate a brake caliper or wheel cylinder.

The measure of an engine's horsepower without the loss in power caused by the gearbox, generator, differential, water pump and other auxiliaries. The actual horsepower delivered to the driving wheels is less.

Metal tubing and rubber hoses which connects each brake caliper or wheel cylinder to the brake master cylinder.

The replaceable friction material which contacts the brake drum in a drum brake system to slow or stop the car.

A cylinder containing a movable piston activated by pressure on the brake pedal. The piston produces hydraulic pressure that pushes fluid through the lines and wheel cylinders. This forces the brake lining or pad against the drum or disc to slow or stop the car.

Brake pads are used specifically with disc brake systems. The pads fit inside the calipers, and create friction and stopping power when pressed against the brake rotor. In a disc system, they are the replaceable flat segments consisting of a rigid backing plate plus frictional lining that takes the place of the shoe and lining in a drum brake. When you have your disc brakes replaced, it is often just the pads that are being replaced. Brake pads are sometimes referred to as brake pucks.

The pedal to the left of the accelerator pedal that controls a car's brakes. When you step on the brake pedal, the car slows down or stops.

When a vehicle moves unexpectedly left or right as you press the brakes, that's pull. The brakes may be out of adjustment or the tires may need more air.

If you can feel the brake pedal, steering wheel, or the entire car vibrate as you step on the brakes, have the brakes serviced.

Brake rotors, or discs, are fitted to most modern cars. They are flat, circular plates that rotate with the wheel when you drive. When you step on the brake, the brake calipers squeeze the brake discs, slowing or stopping the car.

Brake shoes are used specifically with drum brake systems. The term is however, usually applied to the assembly of the brake backing and lining. It is the arc-shaped carrier to which the brake linings are mounted in a drum brake. Brake shoes fit inside the brake drum, and are pressed against the drum by a wheel cylinder when the brakes are applied, thus slowing or stopping the car.

A procedure generally used in performance tests to improve the off-the-line acceleration of a car equipped with an automatic transmission. It is executed by firmly depressing the brake with the left foot, applying the throttle with the car in gear to increase engine rpm, then releasing the brakes. Brake torquing is particularly effective with turbo charged cars because it helps overcome turbo lag.