Firewall (automobile)

automotive engineering Automotive engineering, along with aerospace engineering and naval architecture, is a branch of vehicle engineering, incorporating elements of mechanical, electrical, electronic, software, and safety engineering as applied to the design, manufactu ...

, the firewall (American English) or bulkhead (British English) is the part of the automobile body (

unibody A vehicle frame, also historically known as its '' chassis'', is the main supporting structure of a motor vehicle to which all other components are attached, comparable to the skeleton of an organism. Until the 1930s, virtually every car ha ...

or body-on-frame) that separates the

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...

compartment from the passenger compartment (driver and passengers). It is most commonly a separate component of the body or, in

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

construction, a separate steel pressing, but may be continuous with the

floorpan The floorpan is a large sheet metal stamping that often incorporates several smaller welded stampings to form the floor of a large vehicle and the position of its external and structural panels. In the case of monocoque designs, the floorpan ...

, or its edges may form part of the

door pillar The pillars on a car with permanent roof body style (such as four-door sedans) are the vertical or nearly vertical supports of its window area or greenhouse—designated respectively as the ''A, B, C'' and (in larger cars such as 4-door s ...

s. The name originates from steam-powered vehicles, where the firewall separated the driver from the fire heating the boiler. In aviation, a firewall on an aircraft isolates the engine(s) from other parts of the

airframe The mechanical structure of an aircraft is known as the airframe. This structure is typically considered to include the fuselage, undercarriage, empennage and wings, and excludes the propulsion system. Airframe design is a field of aerospa ...

. In single-engine aircraft, it is the part of the

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

that separates the engine compartment from the

cockpit A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft. The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...

. In most multi-engine propeller aircraft, the firewall typically divides the

nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...

from the wing of the aircraft, or divides the nacelle into two zones. Aircraft components Automotive body parts {{Aviation-stub