Yes, it is like the plate from Stovebolt (Tom Langdon). I have one. The plate on eBay was machined differently.

I use water with mine because it circulates throughout an Offenhauser intake and the intake will never get hotter than the coolant temperature.

It seems to me that by using exhaust air the heat transfers by diffusion and not by circulation. Don't know if that is good or bad or neutral. The hot-air hookup sure looks nicer and is easier than running hoses to the water pump and/or thermostat housing.

There was a comprehensive discussion on heated air vs coolant in this forum during this past year.

Tim