It's that cowling if you ask me. It seems to "cup" around the head of the engine. The hottest part of the head is mostly covered up. I'd also say get creative with baffles. You almost need to make a radial baffle that goes around the prop shaft and angles all the air to the right side of you engine compartment. Not sure how to do that but the center of the front cowling is where all the air comes from. Just blocking the left half of the air entry would probably help. Make that block on an angle and you would have something. Light balsa painted black.