Leaning AT peak ... not ROP or LOP

Ed Haywood said:
Please note I am talking about at peak, not lean of it.
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I run 65% max in cruise. Below 9,000 or so I do LOP, at 11 I'll usually be at peak (with the cylinders straddling peak like @azure says), and up higher I'll be ROP because I can't develop enough power to hurt the engine that high.

Ed Haywood said:
The Lycoming field service rep at Oshkosh was asked about LOP, and gave a very good engineering answer why they do not recommend it.
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"It'll hurt our cylinder sales"? ;)

RyanB said:
My mechanic doesn’t recommend it either. Saving a few bucks on fuel isn’t worth replacing a cylinder or two down the road.
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:rofl:

In the 1200 hours or so that I've had my plane and run it LOP, I've likely saved $30,000 in fuel by doing so. That'd buy a lot of cylinders...

RyanB said:
Serious question - why is Mike Busch so romanticized? Is his opinion more credible than the other thousands of well seasoned IA’s?
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It has nothing to do with him being an IA, though he's not just an IA, he's an IA with access to more engine data than even the manufacturers are likely to have (via Savvy Analysis).

It has more to do with him spreading the knowledge of his friends John Deakin, George Braly, and Walter Atkinson of the former Advanced Pilot Seminars... And their knowledge was primarily gained via actual testing of engines at Braly's companies (Tornado Alley Turbo, GAMI, etc...)

It's not just random dudes who made something up, an awful lot of testing went into it.

geezer said:
The chemistry and operating practice of huge steam boilers for 500 million watt generators have some food for thought on lean of peak.

They have near perfect control of air and fuel flow, typically 32 or more co-axial fuel and air injectors. They have about 8 color TV screens showing the color of the fireball at all crucial areas. The final guide is the redundant stack gas oxygen meters. They read to hundredths of a percent free oxygen. They regulate to as near zero as possible. At the temperatures in the boiler, free, or excess oxygen is at high temperature, and looking for anything to combine with. The boiler tubes and walls are attacked.

Oxygen present shortens time to overhaul "TBO" . Their overhauls cost many millions of dollars, so they give up a tiny bit of unburned fuel to extend TBO.

This means that they are running right at peak, with any error on the rich side.

For your aircraft engine, is there anything inside the cylinders including valves and exhaust ports, that could be attacked by super hot free oxygen?

How much are you willing to give up on time to TBO for a little more miles to the gallon?

Edited to add: Consider the thin film of oil that is left n the cylinder bore as the piston goes down on the power stroke, how much will be oxidized by that super hot free oxygen?
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I don't think a continuous combustion engine is particularly relevant to a reciprocating one. The "free oxygen" isn't going to get superheated fast enough to cause damage because it's also getting pushed out the exhaust. If anything, free oxygen would cause your exhaust to corrode faster.

baboss said:
I believe that while Mike Busch may have popularized LOP operations via AvWeb and then his webinars, it was George Braly/GAMI, John Deakin, and Walter Atkinson that really started the movement via their Advanced Pilot Seminars on the subject. Deakin also spread the gospel via his Pelican’s Perch articles on AvWeb.
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This!!! And if you really want to learn lots of great things about how to operate your aircraft engine, you should read the entire Pelican's Perch series. It is fantastic. In particular, I still send people to read "Manifold Pressure Sucks" when they begin operating with constant speed props because it makes so much more sense than anything else I've read on the subject (glaring at the FAA here...)

WDD said:
As some have already mentioned, LOP is fine to save fuel at the expense of going slower. My purpose of flying is not to save money on fuel, it's to get places. I'm running ROP for those extra 10 kts or so. I pull back until it stumbles, richen it until the EGT comes down to 1325 which will make the cylinder temp 380. If it gets higher, I richen a bit to bring it down; if it falls below 380, I lean it a bit to bring it up. Seems to work.

I do need an EIS. Played with a few at Oshkosh, will probably go with another third GI 275 for the EIS function.

(Skylane running a Continental 0 470 R).
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It's pretty hard to get a carbed engine like the O-470 to run LOP smoothly anyway.
 
Mike Busch is mainly repeating stuff from GAMI. George Braly, John Deakin and Walt Atkinson brought LOP out of the closet and into GA. The piston airlines were run LOP and did over 3000 hours between overhauls.

To REALLY learn about LOP operations take the APS course. I wish they would do in person ones again. https://www.advancedpilot.com/onlinecourse.html

BTW, UND issues with valve recession has been traced to running 94UL at 75% power and peak EGT.
 
If and when 100 UL comes out, 94 UL goes away IMHO so the UND experience is somewhat moot.

Was in the Swift seminar / update at Oshkosh. Will require each person to pay a $100 STC. And 100UL isn’t going to cost less, or make the FBO more money. Their plan is to have pilots demand the 100UL from their FBOs, or else pilots will buy gas somewhere else.

IMHO this is an engineering company with a limited view of the real world and limited to zero marking / business / sales awareness.

A successful product that meets the objectives is necessary but not sufficient. Their business model is a non starter. Unless the government bans 100 LL, there’s little chance 100 UL will be available to folks. Even with a ban, how will the STC requirement be enforced?
 
WDD said:
If and when 100 UL comes out, 94 UL goes away IMHO so the UND experience is somewhat moot.

Was in the Swift seminar / update at Oshkosh. Will require each person to pay a $100 STC. And 100UL isn’t going to cost less, or make the FBO more money. Their plan is to have pilots demand the 100UL from their FBOs, or else pilots will buy gas somewhere else.

IMHO this is an engineering company with a limited view of the real world and limited to zero marking / business / sales awareness.

A successful product that meets the objectives is necessary but not sufficient. Their business model is a non starter. Unless the government bans 100 LL, there’s little chance 100 UL will be available to folks. Even with a ban, how will the STC requirement be enforced?
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As an aside, I was reading the Lycoming oil change recommendations recently. If you use UL, the oil change interval doubles.
 
Ed Haywood said:
As an aside, I was reading the Lycoming oil change recommendations recently. If you use UL, the oil change interval doubles.
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Yeah - really looking forward to getting 100 UL. 100 LL makes a mess of the oil, plugs, etc. Nasty stuff.

As another aside, I’ve lost track of where the other guys are at with the paint damage, etc.
 
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Pinecone said:
Mike Busch is mainly repeating stuff from GAMI. George Braly, John Deakin and Walt Atkinson brought LOP out of the closet and into GA. The piston airlines were run LOP and did over 3000 hours between overhauls.

To REALLY learn about LOP operations take the APS course. I wish they would do in person ones again. https://www.advancedpilot.com/onlinecourse.html
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Kinda difficult as Walt and John are no longer among the living, and George is busy trying to get G100UL moving.
 
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