If you build a proper air tight plenum you should solve all your heat issues. Ever notice that Reno Air Racers running these mammoth engines have smaller cooling intakes on their planes then the kitfox has? Most peoples air cooling set ups waste a ton of air. A good air tight plenum uses every piece of air coming into your cowl to cool. A book that has a good chapter on this is Speed with Economy by Kent Paser.
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