I recently read on a different forum that the reason these inferno and ice crusher heaters have such a wide range of heat output. Is due to basically adding a second radiator to the mix... Also you'd never realize the temp swings without a heater unless you had a gauge. I read blocking some of the air supply to the radiator with cardboard would help get the temps up more consistently. So I made some plastic inserts for the grill. Let me know what you guys think. It seems to work better.... Have more heat from the heater. Especially when stopped at stop signs etc etc.