Normally we use three openings to passive coolling the engine :
1. front windshield, 6cm diameter
2. right and left front windows ( driver + front passanger's windows )
3. rear windshield, as big as you like.
Most importantly, tune your engine so it gets maximum operating temperatures around 115C.
On Road : Xray NT1 , RX8 , T4 || Mugen Seiki MRX4-R , MTX4 , MTX3 prospec || Tamiya M03 , M04 || Top Racing Sabre FD2
Off Road : Xray XT8 || Hobao Hyper 8
Radio : Futaba 3PKS || KO propo EX-10 eurus