ORIGINAL: BobH
Remember you need an exit for the incomming air. If it's not sufficient your engine will over heat. I ended up cutting an area behind the engine in the firewall that lets air exit out of the cockpit. Before doing that my engine was running hotter. Even when baffeled.
Great idea about the hole in the firewall. Look at the plans that I have posted. Which is best; hole up top (heat on servo) OR hole down low (heat on the fuel tank). Or is the hot air not a problem to either?