Ernie
Wonder why no one else has jumped in ?
There are a number of factors as to how you manage or treat your engines;
1) experience
2) type of 337
3) mission or profile
4) wx
5) instrumentation........ etc. that affect or that should influence the way you manage the engines.
Simple....run full rich.
Easiest....... >ROP. Safest either/or.
Consider the POH...
Written by the manufacturer for "dummies". It would be yellow and black if written today "Engine management for dummies". Cessna did not design the engines... they are OEM and operating or performance specs should be published by TCM and NOT Cessna. It is based on the instrumentation and influenced by the profile of the 337 owner.
All that said the engines and INTSTRUMENTATION is 40 - 90 yrs old depending on the initial design. The original designers of the IO-360 aren't even around. If you have a JPI, Shaden etc. there is no reason you cannot go beyond the bounds set out in the POH as long as you understand the rules and play by the game. Somewhat more complex when dealing with turbo charged engines due to cyl temps, pressures and intake temps.
Preignition or detonation can destroy an engine in seconds if you are not carefull. Closer to Peak at higher power levels increase your chances of damaging your engine if you are not monitor the engine performance and react quickly. A lack of maintenance increases the risk as well including the unskilled or newbie pilot.
Sooooooooo.
Each case is different. Having proper knowlege and being able to monitor the engines (flying the ac has a higher priority) you can "tweak" the engines to obtain the desired affect.. ie. lower fuel consumption, less carbon, or higher oil temps.... even longer life.
As I said each case is different.
I do run LOP at cruise if I need to stretch a run and I do lean to keep the unburned fuel to a minimum. If I am in the middle of a IFR flight I may just run rich and not worry about the engines.
I DO NOT run between Peak and 60 ROP !!!!
I do run at peak using lower power settings and LOP during cruise at 65% power when I consider it worthwhile. I never run less than 65% power at any time even on most of my long descents. It is important to keep up the oil temps and keep condensation to a minimum.
I won't say how long I have been flying cessna products....
but I can say that I would never go beyond the POH unless I did have some form of advanced instrumentation that I can TRUST. The guages in the 337 is like measuring wind with a wet finger. The "economizer" guage in the 337 is RELATIVE TIT or last cyl EGT and does not represent what other cylinders are doing.. A FALSE POSITIVE indication things are doing fine while the engine can be destroying itself.
now you have my opinion which has not changed since day one. None of this applies to those running around the berry patch on a sunday afternoon. In this case you just need to make sure you have lots of fuel to keep the fires lit.
Wouldn't it be nice to have a Honda VTEC engine with turbos and then you would be totally bored and this thread would not exist.
Bob
