Engine settings / Cold weather

[inspectortag]

I am interested in how to properly set fuel mixtures for cold weather flying .
I have a raptor with a hyper 50 in it , it was 46 degrees last time I flew and leaned out the mixture 2 clicks and still the engine ran quite cool .
Could hold my finger on the back plate till I got back home if I wanted to .
Temp gun read 86 degrees , in the summer it will read 105 to 110 .
I am still new to this hobby and just want to make my hyper happy .
inspectortag :confused:

[heli-cuzz]

You should richen up your fuel mixture as it gets colder and lean it out in the warmer weather. I don't bother with a temp gun, I go by sight{exhaust trail} and sound of the engine, usually you can tell if to rich or to lean. To rich will have a gurgling boggy oversmoky run to it. To lean it will sound high pitch screaming attitude with little or no exhaust trail eventually to an overheating, flameout, possible ruined engine..

[superflyer]

Yep if you gonig to fly winter richen up. I dont reccomend it. But thts your choice. If you going to fy it richen it up for the winter! Brrr! :p

[inspectortag]

I wont likely be flying when it gets really cold , thats when the rex comes out to play and I will spend alot more time on the g3 .
For the next month or so I can still get some stick time in .
I used to race snowmobiles and have become very good at reading piston wash to obtain correct jet settings for any given weather conditions .
These nitro engines are a little hard to get my inspection light to read piston wash ;)
Just kidding thier guys , Following all the forums that I check I have seen both ways to set the mains up and down so I am a little confused .
By the way the temps that I mentioned ar all from the back plate cover .
inspectortag

[heli-fan]

If you're going to use a temp gun you should take the temp from the head not the back plate. I know some guys go by the back plate temp to set up there engine, I can tell you if mine is running hot or cold from the back plate but I can't tune the engine for weather from the back plate. I like to use a temp gun or my Venom temp gauge which is mounted to the side of my raptor. Back to the original question go lean as the temp outside cools rich as it warms up. My O.S. 50 (not hyper) likes the temp between 180 ~ 210 deg f .

[heli-cuzz]

Back to the original question go lean as the temp outside cools rich as it warms up. My O.S. 50 (not hyper) likes the temp between 180 ~ 210 deg f .


You are wrong about that.^^^^^^^^^


Temperature. Hot weather requires a leaner mixture setting; cold weather requires a richer setting. Most people assume the opposite because they treat the mixture needle like a thermostat. It is wrong to assume that colder weather requires a leaner setting to keep heat in the engine and vice versa. Cold air is denser than hot air. The denser, colder air packs more oxygen into the engine, so going from hot weather to cold needs a commensurate increase of fuel to balance ratio of fuel-burning oxygen and the fuel itself. The opposite is true in hotter weather. Going from cold to hot weather requires a leaner mixture setting.

[heli-fan]

You are wrong about that.^^^^^^^^^


Temperature. Hot weather requires a leaner mixture setting; cold weather requires a richer setting. Most people assume the opposite because they treat the mixture needle like a thermostat. It is wrong to assume that colder weather requires a leaner setting to keep heat in the engine and vice versa. Cold air is denser than hot air. The denser, colder air packs more oxygen into the engine, so going from hot weather to cold needs a commensurate increase of fuel to balance ratio of fuel-burning oxygen and the fuel itself. The opposite is true in hotter weather. Going from cold to hot weather requires a leaner mixture setting.

OK so why do my engines run better in cold weather when I lean them out. Must just be because I have special engines.

[Cncguy]

heli-cuzz is correct. I worked for a race engine machine shop for almost 15 years, we measured the altitude density of the air before a race because as the night cooled it could make a border line lean engine burn a piston, even though the engines would show to be running cooler.
The cool air makes the cooling system more efficeint which will mask a lean condition.
The safest thing to do is to over richen your engine on very cool days and take a few minutes to test fly and lean the engine untill it starts to run well.
Also it is not a good idea to run non ringed engines on very cool days because they relly on interferance for compression and on a very cool day the piston is being heated and the cylinder is being abnormally cooled which will cause too much interferance and premature wear. The next time you fly on a hot day it will have too much clearance.
Ringed pistons are more forgiving.
Also on non ringed engines you want to avoid reving the engine until it has warmed to running temperature because the piston heats more quickly than the cylinder.

[heli-cuzz]

OK so why do my engines run better in cold weather when I lean them out. Must just be because I have special engines.

You make think they run better, but your most likely doing more harm than good. Sure a lean engine spins faster, that doesn't make it run better.

[inspectortag]

cncguy
That is the same thoughts i have on the settings .
The only time I have ever seen engines survive a little over the edge is when they have been cryogenically froze , we have won a world series in sno mo drags in january and believe me jetting them is easy when you know what to look for .
But these heli`s are a little more tempermental to tune correct , probably due to the higher rpm`s they turn . I thouroughly understand teardowns and dont want to do it due to a stupid mistake on my part .
Thanks for all the reply`s on this thread , been real helpful .
inspector :D :D :D