I was fixing the pilot light on someone's boiler and got to thinking. Pilot lights are standalone controlled little propane burners. No wires, no external stuff just gas pressure and the voltage generated by the thermocouple. Looked it up and guys say they put out 900-1500 btu of heat. Call it 1000 btu, and that's 300 watts. Better than a lot of factory engine heaters.
Old ALH EGR cooler heat exchanger, oriented vertically underhood, pilot light assembly underneath, thermosiphon providing pumping. Get the gas valve from an old water heater that has the spark igniter. 20lb tank in the car somewhere, turn on the pilot and light it when you park to keep the engine warm-ish overnight
no 400' extension cords needed
Old ALH EGR cooler heat exchanger, oriented vertically underhood, pilot light assembly underneath, thermosiphon providing pumping. Get the gas valve from an old water heater that has the spark igniter. 20lb tank in the car somewhere, turn on the pilot and light it when you park to keep the engine warm-ish overnight
no 400' extension cords needed