I’ve heard that just a NACA scoop feeding the front oil cooler will make for a chilly ride when its <20F. What is needed is cabin air recirculation across the oil cooler to get reasonable cabin temperatures. So, I modified the NACA scoop and put a baffle in that can be used to shut off outside air flow, and added ducting to accept recirculated cabin air (via a hamster wheel fan). I still need to figure out a place to mount the recirculating fan and route a control cable to actuate the baffle, but it turned out to be a relatively easy modification.
