But, you are just trying to heat up a quantity of air, enough for a rev or two... once it fires at all, it doesn't need the extra heat. Even so, with a 'cold blooded' IDI, I doubt it would work. With a cummins grid heater, I'm not sure it's actually needed - I think it's just to try to reduce smoke/emissions on startup. That being said, I think you might have a shot if you were using one of those propane shop heaters, you know, the 50,000 btu type. Alternately, why not just heat the block/coolant? We know that works, and that you can get a diesel-powered coolant heater for when you have no electricity(webasto makes them).