I thought with a small spread (e.g. GAMI injectors) and the right instrumentation ANY engine could be flown LOP. And I thiunk i have seen articles about flying the Lycoming version of the PA-46 LOP … might be wrong though
Almost all Conti PA46s are flown LOP.
Almost all Lyco PA46s are flown ROP, and can’t be flown LOP.
Why?
Because that’s what the respective POHs say.
Because that’s what the respective POHs say.
Isn’t that in the same category as Lyco “not saying LOP is OK” for any Lyco engine (with the possible exception of some TIO-540 variant, IIRC)?
This kind of thing ought to have been worked out of the system 5-10 years ago.
Certainly, with a 1+ USG/hr GAMI spread I would be doing the injectors ASAP because not only one is burning some 15-20% more fuel for the same distance but one is also bunging up the engine with deposits. And the engine will be running rough (vibration-wise) unless kept very rich on the richest injectors.
Isn’t that in the same category as Lyco “not saying LOP is OK” for any Lyco engine (with the possible exception of some TIO-540 variant, IIRC)?
Exactly, but many people learn (and never unlearn) to do things by the POH. Can’t blame them, really, since when you are still a beginner pilot, you have to stick to something.
Even if you are a seasoned pilot, it is very difficult to distinguish between those things which are in the book for a specific (and valid) reason, and those that are there merely as a result of some lawyer intervention, or those where the manufacturer was simply wrong (or was proven wrong 40 years later).
Re the Malibu: it was always said that the Conti in the Malibu was “designed” to be run LOP, whereas as Lyco in the Mirage was not designed to run LOP. That obviously comes mostly out the marketing department (these engines are very similar in the overall capability to run LOP), but still.
The 1.2GPH spread of denopa is certainly rather high, making that engine indeed “not OK for LOP”.
To be clear: the PA46 pilots I interact with (mostly via MMOPA) are knowledgeable enough to know better than just follow the POH blindly. Many have tried LOP in the Lyco, and most find their engines do not work well there, even with Gamis. There are many theories why…
There are many theories why
I wonder what they are…
Lycos run at peak EGT or (at least slightly) LOP in all other applications, where you have matched injectors.
If there is an inadequate air supply (the case in some tightly cowled installations) the two options are ROP or LOP. Both produce a cooler engine.
The main argument is the difference in ignition timing; the Lyco is set at 20BTDC which is too short for the slower combustion at LOP (the Conti is at 24BTDC).
I have no idea if that’s true for other installations.
That’s a very interesting point, because I can’t go very deep LOP (IO540-C4D5D) despite having very closely matched GAMIs (done in two steps) and very closely matched magnetos. So I fly between peak and about 30F LOP.
In your case you may need to go deeper LOP to get the CHTs down far enough for the level of engine cooling provided.
That’s in the “red box”, is it not?
