Old Akro,
In the past, the engines that I have run LOP have not had LOP prohibited by the engine operators manual. Using the Deakin / APS leaning techniques were not in conflict with the engine operators manual.
First, let me gently take issue your "Deakin / APS" comment. While I love the attribution, and I wish I could take credit, t'ain't so. Nor is it an "APS method" as we didn't invent it. The method has been described in the literature since as far back as Lindbergh's flight across the Atlantic. (I know you know this, but for historical purposes I feel compelled to mention it.)
Post WWII, the airlines re-discovered it, and put it to good use, as well described in "BASIC THEORY OF OPERATION," a 32-page booklet given to all pilots, flight engineers, and mechanics at American Airlines, along with very clear MANDATES similar to "YOU WILL OPERATE THIS WAY." Other airlines and the military got the idea, and the result was about 400,000,000 engine hours of operation on the R-3350 and R-2800. That was directly responsible for those engines going from a TBO of about 400 hours, to 3,600 hours. It was still improving when those wonderful engines were rudely knocked out by the jets, with their stinky fuel and awful screech.
But those engines had BMEP instrumentation, which shows the crew TORQUE directly (with a simple conversion to BHP) in real time. Move any lever (Throttle, Prop, Mixture, Carb Heat) and watch the BMEP needle move right along with it.
We lost that with the "flat" engines, for there is no "Nose Case Reduction Gearing" with the big "floating" ring gear of a big radial, not even on the geared flat engines. Additionally, there are lubrication issues on the Radials that don't apply to "flats," but otherwise, the parts of the engine that are involved in THE COMBUSTION EVENT use the same principles, the same metallurgy and the same processes. For that matter, they are identical in all four-stroke, gasoline engines.
However, the CMI TSIO360 engine operators manual specifically prohibits LOP operation.
Really? Does it say, "NO LOP OPERATION" in the LIMITATIONS section? It would be the first time I've ever seen that in any manual. There ARE POHs that say very specifically, "DO NOT CRUISE ROP," which would be the way to do it, if that's the intent.
What happened here is that the engine manufacturers and the industry discovered very early on that the "flat" engines will simply not run LOP, they shake too much! EVERYONE thought it due to an imbalance of AIR! Instead of fixing the problem, they stuck various notes into the documentation, with varying language from "Cabin Comfort" to "Undesirable Roughness," and over the decades it became accepted, and the lean side of the power curves were forgotten, and became "THE FORBIDDEN ZONE."
It's laughable now, but it took George Braly to discover it was THE FUEL that was unbalanced, and to develop the solution, which opened up the entire chart, and others had developed the "Engine Monitor," which made it clear to the average pilot. But we've still got those engine manuals first written in the forties, fifties and later with the original waffle-language, which will never go away. CASA making any claim otherwise simply makes them idiots.
That they do, and you fine folks must follow their idiotic rules is beyond reasoning, and I cannot address it.
Also, there is a thread on the Beechtalk forum about leaning solely according to TIT where George Braly says that leaning according to TIT is fine and that EGT's are not that important for leaning of turbocharhed engines.
Absolutely true. It has the additional advantage of keeping you out of trouble with TIT limits, which are far more important than EGT, which have NO LIMITS (except for malfunctions.)
However an APS branded seminar delivered to the EAA (by I think Mike Busch - available on the EAA website) condemned leaning by TIT.
As pointed out, there is no connection between APS and Savvy. I've known Mike for more than 35 years, and normally he puts out much better than average information, but on some of it, he's simply out to lunch.
I can't see any reason why you wouldn't lean by TIT. Surely TIT and EGT have a direct relationship? The numbers might be different, but the curves should be the same shape?
Good thinking. What's more, you're correct.
My third question is leaning in the climb. The engine operators manual and the POH say to climb full rich. This is a pretty frightening fuel flow rate. I assume this is for cylinder cooling. But, I climb at 75% power and Carson speed (117 kts for the Seneca) not Best rate speed (89 kts). So, can I lean to best power settings as long as the CHT is within limits?
Not on most engines, which is one area where Busch goes seriously wrong. He's a HUGE man, and the only airplane he'll fit in is his own Cessna 310q, with TSIO-520s. It's probably the only airplane he's flown. That airplane has a peculiar setup, which makes it possible to use 400℉ CHT as the limit. I think it's a wonderful airplane, but it is NOT the model to use for THIS purpose. It MAY work - for you.
But with your engine, I'd suggest you use MAX RATED POWER, as listed in the LIMITATIONs Section, not the "how to fly" textual material. If there is no time limit on TAKEOFF POWER, use it! You'll get higher (and cooler) sooner, and spend less time. The engine is good for it - at full rich. You should see EGT around 1300℉ in the climb if your engine is properly set up. Which brings us to:
Out of curiosity, I overlaid the mixture / power graphs of the TSIO 360 and its normally aspirated brother. I was surprised at how different all 3 curves are (best econ, best power and full rich). Best economy and best power are not too different below about 80% power (the TSIO version uses a bit more), but full rich figure is about 50% higher. Is this just to provide fuel cooling? And shouldn't the turbo version be more efficient?
Good thinking, again. It's just for cooling. And turbos are not generally more efficient, they are meant to give you more power, higher, with very little penalty in efficiency.
How big can messages be in PPrune, anyway?
Best...
John Deakin