I thought this would be cool to post (did you catch that pun?)
When using a single inverted cylinder like so many of us do it is wise to make sure that it is adequately cooled inside the engine cowling. I have always known about this issue but until recently I never really did anything about it. This all started with an airplane that would die at idle in the glide slope on final approach...I tried everything from changing carb linkage geometry to removing the carb stack. Neither of the before mentioned worked so the only thing it could have been was that my engine was running too hot.
Here are a couple of examples. I used cat food carton card stock for the initial shape then simply laid up fiberglass over it then painted it. No more dead sticks-WOW.

Here are some more pictures, That first one is an EDGE 540 cowling. This one is on my PITTS Challenger. I know it's banged up a bit but the spinner covers up the rash. Again, cat food carton material was used. Curved segments were tack glued then laid up. Notice that in both cases the airflow is redirected to the inverted cylinder area within the cowling.

yes, it's cool

Steve, the late P.E started a good thread, have a look.
http://www.rcuniverse.com/forum/gas-...t-results.html

yes ducting in gassers is quite important. This is my current project.

For greatest effectiveness, dead spots within a cowl should be avoided. Also, hot air removal is just as important as cool ram air entry. I typically will build short dams or hoods in front of the exit holes to help suck out the hot air. My entry area to exit area is seldom more than 1:1.

On my Pitts Bulldog