TSIO 360 leaning questions.

[Old Akro]

John

Thanks for the reply. I appreciate the effort.

Firstly, let me repeat my apology for mis-attributing the EAA presentation to APS. Its what happens when I work from memory.

Next, one of my trivial issues relates to the efficiency of Turbo's. If they aren't more efficient why do basically all modern European engines use them? They should be getting benefit from entropy. In my comments about the TSIO 360 vs the IO 360 I forgot the compression ratio difference. The IO 360 will have greater thermodynamic efficiency because of the higher compression ratio, but I would have thought that the better volumetric efficiency of the turbo - especially with such a crappy inlet manifold - would have more than compensated.

I understand your point about climbing at full power, but I'm having trouble getting over decades of habit. And I'm re-reading your article " Those fire breathing turbo's - part 4" . This article relates to the turbo normalised automatic waste gate TSIO 550. But the TSIO 360 generates so little boost that it can nearly be regarded as turbo normalised (the boost is certainly kidstuff compared with automotive turbo's). And it has a fixed wastegate - which really just means I have to do more work with the levers. Most of the time the engine operates with about atmospheric manifiold pressure (ie 28 - 32 inches). The TSIO 550 & 360 also seem to share the same design building blocks - although I make this assessment without much facts.

Back to the climb. Your article suggests WOT, which I can't do and remain below the 40 inch limit. But the TSIO is rated for continuous power at 40 inches, so I can run at that. You advocate full fine, but (like the your preference in the Bo) I prefer to run 2400 or 2500 rather than full fine (2575). It just feels less hectic.

If I climb at 40 inches and 2500 rpm, (from memory) I think the fuel flows will be above the "full rich" line in the engine operators manual. If I reduce mixture a little (once again from memory) I think the TIT will be maybe as low as 1100. In your article you are suggesting leaning to 1290 TIT below 10,000 ft. So, with the caveat of CHT limits, can I lean further to 1290 TIT?

I can generally climb with lower CHT than I get in cruise (especially in the flight levels). I don't expect CHT to be much of an issue.

Both Piper and CMI list 75% (31.5 / 2474) power as maximum recommended climb power, while 100% power (40 / 2575) is a continuous rating.

I'm a fan of Carson speeds. So I'd like to climb at 117 - 120 kIAS, not the best rate 89 KIAS or the Piper suggested 102 KIAS cruise climb. Once I've got the airplane cleaned up and sorted, 75% gives me a fairly solid 500 fpm through to the flight levels, which I've thought was good enough.

Now we get to the cruise.

Based on Carson's work, about 60% power should be optimal for the Seneca cruise. But, I'm growing to like the speed of about 65%. So far, I see bugger all actual fuel flow difference between 60 & 65%, but I do see a speed difference. For me this will typically be about 28 / 2400 at 8 - 10,000 ft. The 3 blade props seem to like 2400 rpm.

The Piper POH Normal Procedures section refers to the engine operators book for leaning. The CMI OM says to lean according to the power table & fuel flow figures. I truly find this bizzare.

But, the fuel flow / power graph that we are supposed to use as a leaning reference says:

" Continuous operation at fuel flows leaner than 25degF rich of peak TIT is prohibited for all conditions"

I know you will talk about the only mandatory part of the POH being the limitations section, but that is a pretty explicit statement.

In previous aircraft I have flown (mainly IO-540's) I can run a LOP regime that you would approve of (did you notice I avoided saying APS method?), without being in conflict with the engine operators manual. I don't like being in direct conflict with the engine operators manual.

So, I typically cruise at 65% power and 25 degF ROP. Its not what you teach, but at that power setting its not going to hurt and its consistent with the book. Typically this is about 1575 - 1625 TIT depending on the day. Frequently I find peak is about 1650 TIT (maybe 1625 - 1675). But, it uses a lot more fuel than it ought and has higher fuel rates than the CMI best economy table. I have a suspicion that the best economy table might actually be LOP, but CMI aren't admitting it.

In part I'm looking for courage to try "the big pull" and get to maybe 50 TIT LOP.

The TSIO 360 is a relatively uncommon engine that frequently has service difficulties and is typically excluded from the general advice articles. So, I'm being tentative.

Thanks for your interest in helping.