Back in the 1970s I had a Ford Escort 1300 GT, the air cleaner had an intake that you positioned over the exhaust manifold in winter and rotated away for summer driving. Hot Car magazine were doing tests on cars to see if they could improve the BHP for no spend. With the Escort they removed the rotating section of the air cleaner but, critically, left the round rubber connector in place for air flow. They also removed the radiator fan and, combined, gained a 5 BHP increase which was noticeable on a 75 BHP engine. There was only one occasion where the engine started to get too warm, on a particularly hot day in traffic.
Wish I still had the Escort...
Derek.