[Walter Atkinson]

Kyle and Kevin:

Good questions.

1) The data suggests that Kevin is right about not pulling the mixture back on the TC'd engine in the climb. You will find much cooler CHTs during the climb if you do not pull the mixture back. Leave it rich. This is very helpful during the time that you have very poor cooling from low airflow. It will cost you about one gallon total during the climb.

This is different than the NA engines where we recommend leaning to a Target EGT in the climb. Remember, as far as MP is concerned, your engine always thinks it's at sea level. Keep it sea level rich!

2) At 65%, you can play fooseball with the mixture and not hurt anything. Set it anywhere you like as long as the CHTs remain under 380dF.

3) The presence of poor F:A ratios is costing you performance and options. If I owned a turbo Skymaster, I would want to get the F:A ratios balanced so I could use the advantage of the turbo and go FAST. I could operate those engines at much higher power settings in cruise on low FF and go fast while keeping the CHTs cool. That's how we operate the big TCM engines and they do quite well like that.

4) You are giving up only about 2 knots from best power while operating at peak. You save a bunch of fuel. CHT's at peak are almost exactly the same as best power CHTs. Sounds like a good idea to me if it will stay cool.

5) IF it will run smooth LOP, it means that the F:A ratios are balanced and in that case, there is absolutely no reason not to run it LOP--even without an engine monitor. Again, the real reason to have an engine monitor has little to do with ROP/LOP choices. You REALLY need and engine monitor if you run ROP, not LOP. The data on this is very compelling once you see it.