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All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> Exceed RC Support - Nitro Cars >> Running in heat
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Running in heat - 8/11/2007 12:03:38 AM   
BackYardRacer


 

Posts: 381
Joined: 7/17/2007
From: Greer, SC, USA
Status: offline 		Me and my friend have been running our cars the past 2 weeks and they ran fine. This week a heat wave came through and its been like 95-105 degrees. Our cars would run fine a minute or too but loose power and start to bog here and there. We've have our needle valves out from 2-3 turns out. There pretty rich but there still getting hot. We've only ran them twice this week because of the heat. Can you run these cars in over 100 degree weather even if there rich. Nothing broke on them they just get really hot and loose power so we end up shutting them off. During the heat wave we havent got passed 1/2 tank of gas. Its supposed to be much nicer tomarrow and be around 70 degrees in the morning. Hopefully it will work tomarrow.
       Post #: 1

RE: Running in heat - 8/11/2007 3:32:49 AM   
AllAboutFunHobbies



Posts: 2732
Joined: 12/5/2006
From: , TX, USA
Status: offline 		Ya need to cut a hole in the front window of the body in line with the engine so air can flow through to the engine, unless you have buggies. Also you need to tune leaner for hot weather. this is from an RCU thread that one of the RCU guys did for tuning your engine.

This is the part about tuning for weather:


It’s a simple fact: for optimum performance, you must retune your nitro engine every time you run it. Anyone who assumes that the needles can be left alone once they have been set is sadly mistaken. An overnight change in weather conditions may prevent an engine from running or may put it at risk of some damage if adjustments aren’t made to the fuel-mixture settings. Ignoring an engine’s tuning needs compromises its ability to make horsepower. In response to certain changes in weather, equipment and other variables, nitro engines must be regularly retuned.

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.

Humidity. Humidity is the amount of moisture (water vapor) in the air. Moisture in the air takes up volume that would otherwise be occupied by fuel-burning oxygen. Less oxygen means less fuel is required to maintain a proper ratio of air and fuel. High humidity requires a leaner mixture setting than dry conditions.

Barometric pressure. A barometer measures the atmospheric pressure (generally listed in the local newspaper or on the local weather forecast on TV). Higher barometric pressure readings mean more air is getting into the engine, requiring a richer mixture setting to balance the air/fuel ratio.

Altitude. Altitude is an important factor that most of us ignore, yet it affects the engine’s performance possibly more than any other element. The general formula for power loss with increases in altitude is 3 percent for every 1,000 feet above sea level. If you race in Colorado at 5,000 feet instead of in California at sea level, you can expect to lose about 15 percent of the engine’s potential power output, if the engine is tuned properly.
Air is thinner at higher altitudes, which means there’s less fuel-burning oxygen than at sea level. You might sense a common theme here: less air (oxygen) means less fuel to maintain the proper air/fuel ratio. So, running at higher altitudes requires a leaner mixture setting than running at sea level.

TUNING
This chart indicates the direction in which you should adjust the fuel mixture when faced with changing weather and other conditions. It assumes the engine is currently well tuned. You could face any combination of conditions listed in the chart; knowing which way to go with the mixture adjustments is half the battle.
Higher air temperature Lean
Lower air temperature Rich
Higher humidity Lean
Lower humidity Rich
Higher barometric pressure Rich
Lower barometric pressure Lean
Higher altitude Lean
Lower altitude Rich
Higher nitro content Rich
Lower nitro content Lean
Higher oil content Lean
Lower oil content Rich
Hotter glow plug Rich
Colder glow plug Lean


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RE: Running in heat - 8/11/2007 3:11:55 PM   
BackYardRacer


 

Posts: 381
Joined: 7/17/2007
From: Greer, SC, USA
Status: offline 		WoW thanks

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RE: Running in heat - 8/11/2007 4:04:27 PM   
AllAboutFunHobbies



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Status: offline 		Anytime.

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RE: Running in heat - 8/11/2007 8:02:52 PM   
BackYardRacer


 

Posts: 381
Joined: 7/17/2007
From: Greer, SC, USA
Status: offline 		Yea i forgot to ask what the temp of the motor should be it doesnt say that in any of exceeds manuels??

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RE: Running in heat - 8/11/2007 8:13:29 PM   
{GBI}Harryball



Posts: 1232
Joined: 7/14/2006
From: lansing, MI, USA
Status: offline 		210-230 should be right.


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RE: Running in heat - 8/12/2007 12:34:32 AM   
BackYardRacer


 

Posts: 381
Joined: 7/17/2007
From: Greer, SC, USA
Status: offline 		I still cant get my truck running good. I think the low speed needle is fine because when i pinch the fuel line it shuts off inbetween 3-4 seconds. But im geussing its the high speed needle. No matter what i do it still bogs when i hit full throttle. It will go for a second then bog. I've had it from 3-2 turns out and it does the same thing everytime. Please help.

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RE: Running in heat - 8/12/2007 1:00:56 AM   
BackYardRacer


 

Posts: 381
Joined: 7/17/2007
From: Greer, SC, USA
Status: offline 		also im having a little fuel spraying out. not a whole bunch, just about half as much as you would during the break in process.

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RE: Running in heat - 8/12/2007 2:09:22 AM   
AllAboutFunHobbies



Posts: 2732
Joined: 12/5/2006
From: , TX, USA
Status: offline 		lean it out some more on the high side.

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RE: Running in heat - 8/12/2007 2:14:52 AM   
BackYardRacer


 

Posts: 381
Joined: 7/17/2007
From: Greer, SC, USA
Status: offline 		The leanest i had it was 2 turns out. I should go lower?

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RE: Running in heat - 8/12/2007 2:59:50 AM   
AllAboutFunHobbies



Posts: 2732
Joined: 12/5/2006
From: , TX, USA
Status: offline 		If it's still spitting fuel out then I would say yes a little at a time though.

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RE: Running in heat - 8/13/2007 12:33:33 AM   
BackYardRacer


 

Posts: 381
Joined: 7/17/2007
From: Greer, SC, USA
Status: offline 		alright i've gotten the needle valve down to 1 1/2 and its running no better. The temp is going up tho. Right when it shut off i put a digital meat thermometer next to the glow plug and it said it was 216 degrees. The temp keeps going up when i lean it but im not getting any less smoke like i should be when i lean it. From 2 1/2 to 1 1/2 im getting the same amount of smoke. Kinda weird. From 3 turns out to 1 1/2 turns it runs the same. Could it be an air leak?? I dont know if air leaks could happen over time because it ran fine the first weak i got it. i just dont know

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RE: Running in heat - 8/13/2007 1:41:00 AM   
BackYardRacer


 

Posts: 381
Joined: 7/17/2007
From: Greer, SC, USA
Status: offline 		Wow what a difference. All i did was reset the low end even with the silver collar and screwed it back in only 1/8 turn. That made all the difference. I kept thinking it was the high end being to lean but it was the low end that was to lean. way to lean. Now i can help my neighbors because they were having the same problem. One of them havent even gotten to drive theres yet because of major tuning problems. LOL and he's had it for 2 weeks. I think i got it figured out now. Thx again

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       Post #: 13

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