SrTelemaster150

If it were me, would only run 1 true exaust stack W, the other as hollow tubes to promote airflow. 3 exhaust stacks total, 1 @ each scale location W/hollow tubes simulating the additional "scale" pipes. I might consider that myself.

If anything, the increased velocity/volume of the exhaust gases combined W/the cooling gases (hot air) rushing past the louvers should cause a pressure drop & promote even more flow from the chamber behind the louver panel. If you are worried about the heat damaging the fiberglass itself, make an aluminum shield plate & extend it rearward to the louvers. It wouldn't be noticable. You will need to fill in the hole where the fake stacks are cut out anyway. Just make it long enough to reach the louvers where a seam won't be as notceable.

I think that the cooling louvers & hollow fake exhaust stacks combined W/a prop hub driven cooling fan forcing airflow past simple baffles to concentrate the airflow over the fins, will eliminate the need for large holes in the cowl. I'm still thinking about some of the louver panels on the bottom of the cowl, but only after testing shows a need for them. They won't be that noticable when the plane is on the gear or flying.



For my 3-cylinder Radial, I'm thinking that a pair of un-cut, full louver panels where the exhaust outlest are located in the example above might help airflow further. That's if the other modification don't yield satisfactory cooling.

BTW: Congatulation to n8622t for a great looking & performing Wurger. I'm a died in the wool 4-stroker myself.