Firewall (engine)

In automotive engineering, the firewall (American English) or bulkhead (British English) is the part of the automobile body (unibody or body-on-frame) that separates the engine compartment from the passenger compartment (driver and passengers).

The name originates from steam-powered vehicles, where the firewall separated the driver from the fire heating the boiler.

For example, a typical conversion of a production car for rallying will include a metal firewall which seals the fuel tank off from the interior of the vehicle.

In regular stock cars, the firewall separates the engine compartment from the cabin and can, at times, contain fibreglass insulation.

In single-engine aircraft, it is the part of the fuselage that separates the engine compartment from the cockpit.

Firewall in an automobile illustrated by a red line
Cutaway drawing of the 1934 Citroen Traction Avant, showing the firewall
Firewall of an aircraft's engine nacelle