Firewall refers to the metal sheet installed engine compartment and passenger cabin.
- It s the part of the vehicle that separates the engine compartment from the passenger compartment (drivers and passengers) It is most commonly a separated part of the vehicle body or in a monocoque construction.
- Separate steel pressing but may be continuous with the floorplan. or its edges may form part of the door pillars, The name is originated from steam powered vehicles wherein the firewall is separated from the driver from the fire heating the boiler.
The floorpan refers to the large metal shaping that is incorporated with the several smaller welded stampings to form the vehicle floor and the position of its external and structural panels. In the case of the monocoque designs, the floorpan is the most important metal part featuring the body, underchassis, and car size.
It serves as a foundation of most of the structural and mechanical components of a unibody automobile to which the powertrain, suspension system, and other parts are attached.