The Truth is:
 

Ok, after so long time searching, and thinking about the importance of the issue, I came to this conclusion: Here is the Holly Bible, writen by Textron Lycoming itself for smal, normaly aspirated, four cylinder, flat opposed engines, like those found on most RVs.

There is no such thing as a Red Box, as long as you respect four very simple rules of thumb: 000 - 100 - 200 - 400 !!!

000: Peak EGT for best economy cruise under 75% Power

100: Degrees Fahrenheit ROP for max power cruise under 75% Power

200: Never exceed Oil Temperature

400: Never exceed CHT

Take off and climb (till 5000 feet): Full power and full rich...

Lycoming does NOT recomend LOP under no circumstances !!!

As simple as that !!! I will follow what the factory recomends ... Certainly the mother knows her Baby better than anyone else...

Here it is:http://www.lycoming.com/support/tips...Operations.pdf

That's the Lycoming IO360. 2001 model Cessna 172R with the conversion.

Not quite sure where you came up with these numbers. I scanned the document you referenced and didn't find anywhere an oil temp NEVER EXCEED of 200?.
Or a NEVER EXCEED cht of 400?.
Never exceed oil temp is 245?.
Never exceed cht is 500?.
I did see for a recommended oil temp of 165-220?, and recommended cht max of 400?. But these are NOT never exceed numbers.

Personal Use
 

I agree with you! Lets change these numbers to Max temp and Max CHT, they are rounded down for simplicity and for my personal use. (Easy to remember, that's all).
Never exceed (Max) numbers for my own use! I think you cant go wrong using these numbers.

More important is the never ending ROP - LOP issue. Lycoming simply doesn't recomends LOP, that's very clear for me now.

100 degrees ROP (avoid 50, could be a pink box) or just PEAK for economy. If jou want some more economy, just throttle back some more, and/or rew down RPM a little bit, do not go below 2100...

Rvs are such lightweight and fast flying airplanes, they don't need that much power anyway and it's easy to trade speed for economy.

What I'm trying to say is that the secrets about gas savings are not on the red knob, but on the black POWER KNOB.

Personally I like to see oil temp between 200? and 210?.
Oil does it's job better at the higher temps. Up to a point, of course.

But I would contend the "mother's" knowledge is based upon the motivation to avoid paying out big monetary judgments were they to release some instructional information on running LOP and then someone messes it up. The safest avenue for the company as a whole to take is to NOT give out any instructions on running LOP. They then have deny-ability as a legal strategy to fall back upon in the courts.

This is not necessarily a useful "authority" to rely on when analyzing what is the best mechanical, technical, practical method for using LOP operations with your engine. It is really the CYA method for Lycoming to protect their company.

The above opinions are just that. The author's opinion. The views expressed above do not represent anyone else's views, and most certainly, not those of Lycoming. Strictly my opinion only.

Lycoming ROP is Nonsensical
 

Interesting that you say you will follow what the factory recommends and then change the max numbers based on your opinion...

Here is the deal: Your engine will see greater pressures and temperatures following Lycoming's nonsensical 50 ROP dogma than if you go LOP...

Have you read Deakin's articles mentioned in this thread?


Hans

That's just all we are talking about. John Dankin advocates just that Dogma: bevare of the RED BOX, all between 150 ROP and PEAK is BAD. Better stay LOP to avoid detonation and melting your pistons...
Find PEAK crossing the RED BOX quickly doing the BIG PULL...

This may be true for the big bores, but for the smal 4 cyl, Lycoming says just the oposite. There is NO RED BOX at 100 ROP or PEAK,below 75% power, ergo NO DETONATION! Isn't that funny?

Why should Lycoming recomend to operate their smal engines that way, if there where any highly destructive RED BOX ? That's the point...

As Lycoming says: as soon as you lean beyong Peak, you loose power.And speed.So, why not just reduce power(MF) for economy? Fuel flow will reduce the same way as pulling back mixture...

I've operated an IO 540 235 for years operating between 100 ROP and PEAK, at 75% power and below, like the Manual says, and never had any issue.

Science is Key
 

Deakin backs his recommendations with science, Lycoming doesn't. That is why Deakin's recommendations are not dogma and Lycoming's are.

Hans

ROP
 

When I was doing my commercial flight training, we used airplanes with the AEIO-360-A1B6 and almost exclusively used 65% and 100 degrees ROP. Once I checked the logs to see how long the last engine lasted [School had an approved "on condition" program]. 2400hrs! That's with the abuse of simulated engine filures, continous circuits, etc.

Operating an angle valve, 4 cyl lycoming with 8.7:1 compression in the "red box", and it still lasted well beyond TBO.