Variable WAI and CAI.
 

There is a thread running currently on the effects of ram air and WAI which prompted some memories of a set up used on a Citroen of 1950's vintage.

In essence the Citroen arrangement used a metal funnel situated just behind the radiator. There was a cable operation to allow the funnel to move sideways at the driver's choosing. At the trailing edge of the funnel (which was also the pivot point) a tube connected to duct air into the cabin. The air temp depended on the position of the funnel (laterally) as chosen by the driver.

With the funnel pointing directly ahead all air was ambient temp.
To add warmed air flowing through the radiator the funnel was moved by a cable to take some warm air and add it to the ambient temp air.
Moving the heater control to full warm meant no ambient temp air was taken in since the funnel was fully moved over to take all air from that flowing though the radiator. It was also fan assisted by this stage since the funnel was now angled around far enough to have radiator fan air being pushed in as well.

No idea if this is of any use to anyone here but it is an interesting take.

Cheers , Pete.

I think it would be interesting to control this kind of system thermostatically to a particular intake air temperature. Isn't there an efficiency peak associated with intake air temperature?

Chuck,
I am not sure about the optimum intake temperature but yes I agree a thermostat regulator would be a great improvement.

Citroen I suspect had a cost incentive in mind given the huge development costs of the vehicle this arrangement was fitted to !

Pete.