185 Lean of Peak on Floats

[Durango skywagon]

I'm curious about the experience of float operators out there stretching their fuel. My 185 has an 0-520, and I've got 6 place EGT and CHT. Last summer I flew numerous cross countrys lean of peak, it seemed with floats in order to keep the nose down I'd end up flying at relatively high power settings (25 squared). The gami folks say thats fine. I keep CHT's well out of the red and my engine seems happy.

I'm wondering how you guys stretch your fuel especially looking for advice on Lean of Peak. What power settings are you typically using? Any advice on the actual leaning process or finding best endurance power settings?

It seems like avgas in some remote seaplane bases is gonna be high this year a guys gotta do all he can to stretch a dollar.

-Brad

[robertsailor1]

I've been out of this for years but it used to be OK to run Lycomings lean of peak but not Continentals

[trey kule]

Are you looking for endurance or range? 25 squared will not give you endurance I dont think.
I am not sure exactly why you should have to be running a 185 at 25 square in crusie, and you might want to back off the power a bit. Remeber an increase in speed requires a square factor in power. If you plane flies excessively nose high or low it may be a cof g issue caused by rigging or something. 185s have a much different attitude on floats than they do on wheels.

If you have a GEm monitor or similar, they usually come with CD's and manual explaining how to use them properly. It is worth the time to go over these to understand exactly how they work, particularily if you are running lean of peak. There is so much argument, misundersatnding and ignorance on this subject that it is best to avoid it here and go to those who really do know.
Also, the engine manufacturers have exceelent technical departments. Call them and discuss it with them. That way you getting it from the horses mouth and not the other end.

[Adam Oke]

Just recently I've been starting to read more and more into lean of peak operation, and flying over square. Here's the video that sparked my attention. I have yet to fly anything equip with proper instruments to fly lean of peak safety -- so I'm still a rich of peak operator.

http://www.aopa.org/members/files/pilot ... c_sect=gan

[Durango skywagon]

I hear what you are saying Trey. I know LOP is controversial, I've done the research and I do believe in it though and was wondering if there were any other believers out there who operate on floats. As I recall last summer I tried all sorts of power settings and maybe I was at 25 squared or maybe 24. If I ran it any lower though I would get into a nose high wallowing attitude. I even found that with full tanks at gross I'd have to run ROP for awhile before it would cruise at the lower LOP settings.

Also, again if I remember at 25 squared LOP my percentage horsepower on my monitor was right around 75%.

Also, I know Continental doesn't publicly allow it, but when you talk to their technicians they'll tell you they are slowly coming around to it. And further it seems to me they are a poor source of information about their own engines (my opinion).

Again, if there's any other LOP believers out there who have experience heavy on floats I'd love to hear what works for you.

-Brad

[trey kule]

Talk to the technical people at progressive air..I have used them as a base for years, and they are helpful and knowledgable...and for this service, let me put a plug in for them, and say they also offer excellent prices and service.

I think the problem stems from an number of historical issues. Many moons ago, engineers understood two thngs..First pilots are stupid. So if they were flying at altitude and forgot to enrichen the mixture they might just have a problem,if not on the descent in the go around.
Secondly the hardware to accurately lean was not there and EGT guages were a bit simplistic. As a result if you tried to lean past peak you just might have one cyl that was way to lean and burn up valves.
Somehow, over the years that all got morphed. Pilots nowaday are taught to have the mixtures full rich on the final approach to land..None of these wizards ever seem to wonder why the immediae action for an engine failure on a twin is to put the power, props AND mixture controls forward..
Anway, now that we have those nifty little monitors that tell us what is going on in each cyl, we can lean accurately so that the leanest cyl is within limits (no more valve burning), and good CHT/OIL guages so we can monitor it...Voila..time to be efficient.

I did not want to get into detail, but the simple truth is most newly licensed pilots do not really have anyunderstaninding of leaning, or single probe vs. multi probe, or any of the real knowledge necessary to form an opinion. You will note that those who say they are interested all seem to be pro-lean

The real key is your CHTs. and knowing accurately what your cyls are doing.

something still sounds odd about you attitude on the 185 but it has been many years since I flew a 185 on floats. Have you had a tach check recently? It only take a couple of minutes to confirm your tach is correct.

[Durango skywagon]

My Tach is good, though I just tracked down a leak in my MP line. It affected readings at low power (indicated high), not sure what it did at high power. That could be screwing up my numbers.

[CLguy]

Flew a 185 many years ago and 25 squared was the magic power setting for it. Prior years the company had tried lower settings and it was a hangar queen. Higher power settings were used and it hardly ever saw the hangar. If my memory is correct we used to lean to the top of the green on the fuel flow. Of course fuel was much cheaper then but the hangar time was minimal.

[fish4life]

we always fly our 185 at 24 squared and lean it to between 15-16 gph she seems to really like that

[BGH]

I've tried running my 185 at various power settings on both wheels & cap 3000 floats & ended up settling on the 24 squared with book fuel flows.I have a ei 6 cylinder cht & egt monitor.

Not a fan of progressive - bought a factory reman from them & they wouldn't honour the warranty so I had to pay to have the top redone,was told it was soft exhaust guides - a continental quality problem.Didn't matter to progressive though.I could go on but it isn't worth the trouble.

I have experimented with 100 lean of peak & the engine runs fine,with lower temps I might add,but I lost speed when lean of peak so went back to book values.

Daryl

(stock injectors)

[trey kule]

OK. We have obviously had different experiences with Prograssive. How about we leave it at that?

As to your speed reduction yes. You will. The plan however is that for a 5 or 10% speed loss we have a 25 -35% fuel savings. On a 185 on floats, that speed loss does not usually make a huge difference in the block times for a typical flight (think a couple of minutes on every hundred miles), but the savings in fuel at todays prices is significant. Think $22.00 - $25 an hour, for 100 hours a month during the summer. Pays for all the fancy monitoring stuff, which have some other real benefits besides fuel savings, in the first part of the first summer alone.

Now as to the MP guage. Maybe that is the problem, or part of the problem. If you were not developing power at the top end you should have noticed on takeoff, as a bit less than full poser makes itself very noticable.

[BGH]

I paid $1.73/litre yesterday after coming back from Anahim Lake in my 185.I would think that at 100 lean of peak it would have showed about 1 gallon us/hour less on the fuel flow had I chose to run it 100 lean of peak,my memory could be off a bit but if it is close then that would only be 3.78 litres/hour;or about $6.54 savings/hour.Yep that could add up to a significant amount for the year.A friend of mine is replacing his top end because of burnt valves & he told me that he was experimenting with lean of peak on amphibs,don't know if it's related.

Done properly I would think that runing lean of peak would have it's benefits,less fuel flow/hour & cooler running engine,but the big continentals like to be run hard & kept warm for the least amount of troubles.

Daryl

[trey kule]

There are some caveats to this leaning thing you know. Proper instrumentation , and knowing how to use it.
It has been a while, but it seems to me the fuel burn drops from about 17 USGPH to about 13..
thats roughly 14 litres an hour difference depending on altitude, leg distance etc.
As to the valves, with the proper instrumentation in it that should not be happening, and I would hesitate to say it was a result of proper leaning to lean of peak . I did it for years after we got GEM monitors installed without any problems whatsoever. But then neither of our experiences may be typical.
The biggest problem is people not knowing how to do it properly and kind of faking it.
The little video someone posted here is quite good, as are the CDs that come with the monitors..BTW which also give advance indicatin of valve problems and a few other things if you use them properly.

[Durango skywagon]

Thanks for posting this video: http://www.aopa.org/members/files/pilot ... c_sect=gan

It Rocks. And it backs up what the Gami folks had said. I had been looking for backup of the high manifold and different RPM settings in cruise, and wanting to make sure I remembered it right.

Get things set up in cruise with throttle either all the way in or at 25"
Dial back RPM until around 75% power.
Slowly lean until all have peaked, my spread was usually 30 LOP on the richest and 50 LOP on the leanest, I may try and go a bit further in the future.

Thanks for the good discussion.

-Brad

[xsbank]

Once upon a time you could get 100/130 gas and the 185s loved it, loaded with lead and leaning was a breeze. Now that the fuel is "low lead," leaning might be more problematic. I know if you ever tried to run 80/87 (emergency, whatever) you would blow the engine very quickly. That is probably a propos nothing, but one of my synapses fired and I had to get it out!

Mogas in a 185? Is that even possible?

[trey kule]

Once upon a time, long ago, we also were taught, as part of the ppl curriculum what grade of car gas to use when we could not find AvGas...that was a long time ago.

Anyway, just to ad to thread drift, all the STC's I have seen for Mogas (actually about 4) all made it clear that the mogas was not to contain any ethanol. I think all mogas in Canada now contains ethanol so it is not suitable. ( I have never had the need to check anything but the octane ratings..Husky has a 94 octane rating fuel..maybe it is pure gas.). Some people were sharing in a tanker of it brought up from the US which did not have ethanol.

As to the 185, I cant recall every trying mogas in one. It is stinky dirty gas anyway, and it has some altitude limitations in the STCs.
A a matter of fact,in my old fading memory, I dont recall using mo gas in anything other than carborated engines..The old radials ran just fine on car gas years ago.

[nutbutter]

Ive got lots of professional time on the 520. It likes to be operated at 2300 square or 2400 square. I always try and keep in mind RPM's and detonation kills engines, therefore the lower the rpm you run it at, the longer she lasts. As for detonation, a rich motor is a happy motor, lean of peak causes detonation. That said, all the commercial operators ground lean by about two finger widths for the 520, or wherever your engine happens to have its ground lean spot, be very careful not to add takeoff power with the engine still leaned as it will cause detonation. Always stage cool her, they like to have the throttle pulled back an inch per minute or so for about 7 mins prior to inspection pass (From 23" MP that brings you to 16 or 17"). The float equipped 185 is an absolutely wonderful machine if u approach at about 11-12 inches, 80kts, and 20 degrees of flaps she practically lands (From 500ft all the way to the ground) herself and is very docile in the process even in gusty winds. Enjoy

Edit: Reduce to 25 squared as soon as safe after take off (Flaps to 0 first), moving throttle first then prop lever. Always keep that throttle setting lower than the RPM setting. Also, be very careful with the cowl flaps on a hot day, I wouldn't even close them on a short haul flight, and don't have the oil and cylinder temps cool at different rates (make sure those two needles cool together). PM me if you want some more info.

[photofly]

As for detonation, a rich motor is a happy motor, lean of peak causes detonation.

That's a contentious statement, to say the least.

[nutbutter]

As for detonation, a rich motor is a happy motor, lean of peak causes detonation.

That's a contentious statement, to say the least.

Obvious troll. Look I don't care how anyone operates "their engine," its none of my business, but I will point out that most commercial operators out there use that exact prescribed procedure I gave, or a variation thereof for operating an IO-520. Also I will point out that the laws of physics don't suddenly change when you put "Gami" injectors in an airplane, which still uses a mechanical fuel injejection system that was designed long before I was born in an air cooled engine. I'm not sure how the general aviation market became convinced that operating leaner than rich, especially with such ancient technology (Its not even sequential fuel injection, nor does it use throttle by wire that cars were using 20 years ago), is acceptable just b/c u spent all that money on a fuel totalizer and a matched set of injectors. I don't particularly care either.
But what I do know for fact is that in a 100 years, the billions of dollars, and hundreds of people sacrificed in the name of motorsport, Ferarri's, and Honda's still to this day run rich of peak in the pursuit of 15000rpm, peak horsepower, and maximum reliability.
Ask those engine builders in California who build 12000rpm 300hp from bone stock Honda 4 cylinder engines how they map their fuel, or pick up one of the many text books written on the subject and read how to do it yourself.
Engines are mapped a bit rich of peak for the purposes of running balanced, valve cooling, and preventing detonation.
If you don't believe me, ask an operator who has about 10+ IO520's in their fleet, they probably go through multiple engines per year, and can enlighten you on the subject.
Again, I was just trying to help, don't take my word for it, figure it out yourself.
gfy photofly

[GoinNowhereFast]

Flying LOP won't hurt an engine if you use low power settings. For higher compression, normally aspirated engines like the IO-520, I'd be scared to go above 23" and be LOP. That works great in little over-powered rocket-ships, but in a C185, run it 24 squared, and 100 degrees rich. If you want to save a little gas, try 23 squared.