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Old 12-04-2008, 11:15 PM   #1
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Default How to tune Engine for night driving

Hi all,

Can someone tell me how to tune engine at night when it is 20-25 degree cooler? Someone at the track say to rich it up and also run colder plugs? Is that ture? It does not seem right. I always thought you lean it out a bit becasue the outside temp is cooler. Also run a hotter plug to keep the engine a bit warmer.

Also what happens when the enviroment is damp/foggy? do you lean out or rich up the engine?
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Old 12-04-2008, 11:27 PM   #2
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Hi all,

Can someone tell me how to tune engine at night when it is 20-25 degree cooler? Someone at the track say to rich it up and also run colder plugs? Is that ture? It does not seem right. I always thought you lean it out a bit becasue the outside temp is cooler. Also run a hotter plug to keep the engine a bit warmer.

Also what happens when the enviroment is damp/foggy? do you lean out or rich up the engine?
yes at night when it's clear out, colder plugs, and or richer settings...
damp fogg hotter plug..
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Old 12-04-2008, 11:44 PM   #3
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Lower air temps..Rich
Higher air temps..Lean
Hotter glow plug..Rich
Colder glow plug..Lean
Lower humidty..Rich
Higher humidity..Lean
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Old 12-04-2008, 11:58 PM   #4
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Cold air contains a denser charge of oxygen in a given volume of air. As such you have to add more fuel.

When the temperature rises or the humidity is up there is a less dense charge of oxygen so you have to take some fuel away by tuning leaner.

Basically the engine can only burn as much fuel as the oxygen charge in the air will allow. Higher temps equal less oxygen, lower temps equal more oxygen.

I myself do not change glow plug temps at all. The typical temperature that we race our Nitro vehicles at around here is between 70 and 90. Spring to Fall. As such I just tune the needles for the air temp and humidity and leave it alone.

If I were to run in the 35 or 45 degree weather we are having now I would go to a different plug... but I believe it's too hard on the engine to run in this kind of weather so I just run electric indoor in the winter time.

Wish I could explain my explanation of Oxygen charge better.. Thats the best I can come up with though.

Hope it helped.
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Old 12-05-2008, 12:04 AM   #5
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To run at night, I need to lean out (from my daytime 225 setting) a little to keep running at 225. If I rich it up my engine won't run right it gets too rich.
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Old 12-05-2008, 04:20 AM   #6
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Originally Posted by DavidR View Post
Cold air contains a denser charge of oxygen in a given volume of air. As such you have to add more fuel.

When the temperature rises or the humidity is up there is a less dense charge of oxygen so you have to take some fuel away by tuning leaner.

Basically the engine can only burn as much fuel as the oxygen charge in the air will allow. Higher temps equal less oxygen, lower temps equal more oxygen.

I myself do not change glow plug temps at all. The typical temperature that we race our Nitro vehicles at around here is between 70 and 90. Spring to Fall. As such I just tune the needles for the air temp and humidity and leave it alone.

If I were to run in the 35 or 45 degree weather we are having now I would go to a different plug... but I believe it's too hard on the engine to run in this kind of weather so I just run electric indoor in the winter time.

Wish I could explain my explanation of Oxygen charge better.. Thats the best I can come up with though.

Hope it helped.
I wouldn't say it's hard on them as long as the running temp is kept at or above 200. Running it cool at full revs could be a problem though.
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Old 12-05-2008, 12:39 PM   #7
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i never change plugs just the needles a bit
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Old 12-05-2008, 03:44 PM   #8
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To run at night, I need to lean out (from my daytime 225 setting) a little to keep running at 225. If I rich it up my engine won't run right it gets too rich.


FINALLY someone sees it the way i do
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Old 12-05-2008, 04:12 PM   #9
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Don't tune to a temp! Some days it will run at 220 and others 260 and that is fine.
Losiracer you are going to blow some engines if we can believe what you have written in the other thread
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Old 12-05-2008, 09:22 PM   #10
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well when my motors will not start when its 50 degrees out because it cooled down then i would say im right to lean it out.
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Old 12-06-2008, 02:01 AM   #11
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LMAO...

I guess that everything I've (and almost everybody else on this forum have) ever learned about an engine is wrong...

Guess I'll throw all my automotive tuning equipment away and all my nitro engines for my R/C stuff... Cause I guess I don't know what I'm doing.

I urge the rest of you to do the same!! We're just gonna blow our stuff up!?!?

Cause according to losi_racer the majority of us are wrong and everything that we learned in middle school science classes about air density is wrong.

This kind of stuff is why I just keep to myself on these boards... There's always somebody who will just repeat over and over the same damn thing even though they're dead WRONG! If they'd just listen to reason and use their brain there wouldn't be an argument like this that spans two seperate threads!

losi_racer.... You need to brush up on your middle school level science bro. I wish you the best though in tuning your motors though.

As for the original poster who asked the question... A few of us have given you sound advice. Scientifically backed advice. Not just personal opinion. You choose who you want to believe.

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Old 12-06-2008, 02:22 AM   #12
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Thanks David. I was going to say that but I'm new here so I tamed mine down a bit ;-)
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Old 12-06-2008, 05:18 AM   #13
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elevation, and humidity have more to do with it than ambient temp.
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Old 12-06-2008, 07:05 AM   #14
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Originally Posted by DavidR View Post


LMAO...

I guess that everything I've (and almost everybody else on this forum have) ever learned about an engine is wrong...

Guess I'll throw all my automotive tuning equipment away and all my nitro engines for my R/C stuff... Cause I guess I don't know what I'm doing.

I urge the rest of you to do the same!! We're just gonna blow our stuff up!?!?

Cause according to losi_racer the majority of us are wrong and everything that we learned in middle school science classes about air density is wrong.

This kind of stuff is why I just keep to myself on these boards... There's always somebody who will just repeat over and over the same damn thing even though they're dead WRONG! If they'd just listen to reason and use their brain there wouldn't be an argument like this that spans two seperate threads!

losi_racer.... You need to brush up on your middle school level science bro. I wish you the best though in tuning your motors though.

As for the original poster who asked the question... A few of us have given you sound advice. Scientifically backed advice. Not just personal opinion. You choose who you want to believe.

</Rant>
Don't stop giving out good info., just because you got one person who don't take the time to do there home work before responding. Believe it or not people like you help more new and old racers and do more for the sport than he or she could ever do. Just keep doing what you doing and the sport will continuing to grow thanks and by the way you right. I used think like he do but did my home work years back and learned.
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Old 12-06-2008, 09:34 AM   #15
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itsshemp - I actually agree with you to a certain extent. I do feel that those "forces" are also the hardest to adjust for... Most of us don't have the equipment to tell us that the humidity is up, or the barometric pressure is down... or whatever. So you have to adjust for this by "feel".

So basically... for the same given air temperature... Humidity and barometric pressure can change and leave your tune all screwed up.

As for altitude... That's honestly a non issue as far as adjusting for the night time, since the altitude (obviously) isn't gonna change on you as long as you stay in the same location.

As for my rant last night... I'm sure I'd actually have a hard time not helping people with these kinda things... I enjoy sharing my hard earned knowledge.

I don't claim to be the smartest person in the world about this stuff.. but there are some things that I know to be fact! This is one of them...

But thanks guys for the kind words guys...
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