Gearhead [geer-hed] Noun
A person who is into all things motorized. This can be cars, motorcycles, machines, planes, or boats, but specifically relating to the engine and power delivery. Knowing how to weld and machine metal are also traits of a gearhead.
Dude, she’s such a gearhead. Go show her that old lathe and tools in your grandfather’s garage and she’ll be in heaven.