SOLD Air Compressor from a Land Rover. Common 12V -ground; easy to wire up. Can fill a 10L tank to ~200psi in 7-15 minutes. 3 rubber-bushed mounting tabs. 7.25Lx5.5Hx3"W (5"W across the mounting bracket; 10"L including filter & rear bracket) @ 6 lbs. Some have 6" wires (shown); others have 12". Inlet & outlet are pipe-threaded, and the whole thing is sealed, so it can be plumbed to run underwater. Most include an intake filter & all include an outlet compression fitting. They also have a built-in thermal switch (orange wire normally grounded; open when hot) that you can wire up if you choose, but it doesnt interfere with the motor - its just an output signal. The motor pulls 3A @ 0 pressure; 8A @ max pressure.
This shows one way of wiring it up:
http://www.supermotors.net/vehicles/registry/media/280959 
