sonex1374 wrote:Likewise, we also know that not overheating the engine is key to long life.
That's the key. And, running the engine too cool is not likely to be a problem for an Aerovee pilot. I think the best approach is to keep the engine as cool a practical. For my particular case, a Onex, there are two things I can do to keep engine temps down.
1) Optimize the geometry of the cowl exit.
2) Operate the engine at the appropriate mixture.
From Sonex LLC web site, here is a pic of Drew flying a Onex. Notice that there is no lip on the small cowl exit. Wisconsin is a wonderful place in the Summer.
The Onex prints have been revised to increase the size of the cowl exit and a lip is added to the enlarged exit. In the particular case of the Onex, since the nose of the cowl is already pretty much open, the cowl exit is really the only variable that can be "played with" to increase cooling. Again, I wish there was some reading material I could find that explains the effects of cowl exit geometry on pressure reduction (suck factor) vs. drag.
As far as mixture is concerned, most of us don't have fuel injection and will be running rich of peak to keep things cool. The only question is how rich. If you look at the graph shown in the article Graeme referenced, and ignore the numbers, it does explain the relationship between mixture, power, temperature, and fuel consumption.
Wes