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Dial

An instrument with an analog-gauge indicator.

Dial In

1. To set the Christmas tree for drag racing events, with the interval between starting times for vehicles with different indexes. 2. To set up a car with the right combination for maximum performance for any particular racing condition.

Dial Under

A practice allowed under NASCAR rules in handicap eliminations for Stock and Super Stock classes where the breakout rule is in effect.

Diameter

The cross-section measurement of a round or circular object.

Diamond Plate

An aluminum plate that features a raised design to provide skid resistance and increased strength. Often used for pickup truck accessories, including running boards, bed caps, tool boxes and even tonneau covers.

Diaphragm

1. A flexible membrane in a speaker or microphone where electrical signals are converted to sound vibrations and vice versa. 2. The flexible membrane found in a temperature- or pressure-control device that seals in an inert fluid from the atmosphere while allowing a mechanical movement.

Diaphragm Clutch

A clutch having a shallow, cone-shaped spring disc to provide pressure to the plate.

Diaphragm Spring

1. A spring shaped like a disk with taped fingers pointed inward. 2. A spring shaped like a wavy disk.

Diaphragm-spring Clutch

A clutch in which a diaphragm spring applies pressure against the friction disk.

Diatomacoeus Earth

(Kitty Litter) An absorbent material containing an abundance of diatoms or their siliceous remains.

DIC

Driver Information Center.

Dice

A tight contest between two cars on an oval track or road course generally battling for a specific position.

Dichlorodifluoromethane

The proper chemical name for Refrigerant-12.

Die Out

To stall or stop running.

Dielectric

1. An insulator. 2. A term referring to the insulation between the plates of a capacitor.

Dielectric Grease

Lithium or silicone based grease used to lubricate, protect from moisture, and dissipate heat while acting as a non-conductor; applications include light bulb sockets, spark plug boots, distributor caps and under ignition modules.

Dielectric Strength

The ability of an insulator to insulate; to resist carrying current without damage. 2. The resistance to electron penetration.

Diesel Cycle

An engine operating cycle where the air is compressed and the fuel is injected at the end of the compression stroke, causing ignition.

Diesel Engine

A compression-ignition engine.

Diesel Engine

An engine that relies on the heat generated by a high compression ratio about 23