Power, prop and mixture for Cruise flight

[Brenton C]

Ok, this is a topic that's been bugging me for a while. I was planning on getting an engine monitor straight away, but thats probably gonna have to wait a while.

So in the meantime, how do you guys manage your power, prop and mix for cruise?

[John Ashcroft]

Brenton
I could not be regarded as an authority, if i am just stooging around 20"23mp
In cruise generally 23/23 m5235c

[Brenton C]

Thanks John,

That'll probably get me pretty close, as I have the M5-210.

[Steelroamer]

I was just going to ask that question.

I am going on a long trip next week to the shores of Hudson Bay in Northern Ontario and fuel is going to be an issue. There is a really good post that I just read on back country pilot.org website that raised a few questions
https://www.backcountrypilot.org/forum/ ... 95#p245295

I normally fly my 0-540 at 23/23 and full rich below 5000' as per my lycoming manual and what I have read (I could be reading it wrong)

Does anyone fly over square 23"/2000 rpm?
Does anyone lean their big bore below 5000'? providing EGT stays around peak and CHT stays below the red line?

thanks
Roamer

[Brenton C]

Roamer,

Sounds like a nice trip! I'll read that link with care and interest.

I read a bunch of stuff on the web by Deakin, and by Mike Busch, as well as Busch's webinars on the EAA website.

My shaky understanding is that so long as you're below . . . I think it's 70% power on Lycomings, 65% on Conti's . . . (might have those numbers wrong), then you can lean to where ever you want, and you'll be ok so long as you keep a 380 degrees as your max operating CHT, and consider 400 (not 500) as "red line."

One thing Busch said about the carbed 540 engine is that with throttle to the max, the engine runs just a little extra rich to assist in full power take off and climb, so when cruising, you should back off from full throttle just a tad, before turning your attention to leaning.

[Rezrider]

I was just going to ask that question.

I am going on a long trip next week to the shores of Hudson Bay in Northern Ontario and fuel is going to be an issue. There is a really good post that I just read on back country pilot.org website that raised a few questions
https://www.backcountrypilot.org/forum/ ... 95#p245295

I normally fly my 0-540 at 23/23 and full rich below 5000' as per my lycoming manual and what I have read (I could be reading it wrong)

Does anyone fly over square 23"/2000 rpm?
Does anyone lean their big bore below 5000'? providing EGT stays around peak and CHT stays below the red line?

thanks
Roamer

You need to be leaning that thing back. You're not doing anything any favors by flying full rich, just using more gas than you need to.
Forget about EGT's and focus on CHT's if you have an appropriate engine monitor.
Read Mike Busch's articles on CHT's.
Go up and experiment with various settings to see what works.

[Steelroamer]

Thanks rezrider,

It certainly is a learning curve. Read everything I could find that mike Busch has on the subject

How about running over square?

Roamer

[Mountain Doctor]

This article has a section on how thee in no harm on running oversquare:

http://www.avweb.com/news/maint/182849-1.html

[TomD]

Don't know if this helps or not but saw this on Backcountrypilot.org site.

Too long to copy and paste. If you cannot read it let me know and I will copy and paste.

https://www.backcountrypilot.org/commun ... lies-17775

[UP-M5]

i typically run around at 22/22 with my -j1A5D. and i have to lean just after first power reduction (in the summer- not so in the winter) and anywhere above about 2000' MSL i will need to lean more.
at work we use oversquared for cruise, a 300hp cherokee 6, for example, with IO-540 we climb at 25/25 and then go to 2300/24". i replace the engine every 4 years- because it makes TBO just fine. usually with no oil leaks and no cylinders having been changed.