Is it really hard on a engine to run in cold temps?
12-05-2008, 03:53 PM
#16
Interesting.... I disagree. Actually, this is really backwards. An engine needs more fuel on a cold day. Since the air is denser, the engine needs more fuel to find the optimal fuel/air ratio. The air is denser and so it will need more fuel to operate well.
I really think you are just pulling a forum prank here. Otherwise, let us know how this works out for you.
12-05-2008, 03:54 PM
#17
Being that I am from the midwest, we see a wide variety of temperatures and race in all of them. In the summer, it can reach upwards of 100 degrees and in the winter months can get below zero. I think the main thing is to keep the engine tuned to the temp that you are running in. I also believe that pre-heating the engine is a great thing to do.
12-05-2008, 04:14 PM
#18
losi_racer,
You can believe, and tune how you think its best for your motor to achieve maximum performance/lifespan. But your philosophy on how motors should be tuned for atmospheric change is wrong, but there your motor's. Best of luck....
You can believe, and tune how you think its best for your motor to achieve maximum performance/lifespan. But your philosophy on how motors should be tuned for atmospheric change is wrong, but there your motor's. Best of luck....
12-05-2008, 06:05 PM
#20
Let's put this to rest. I keep on hearing it is tough on a engine to run in cold outside temps (30*-50*f). I am having a hard time buying this unless you are unable to get the engine to reach its good running temp. I heat my engines up before starting them, and my running temps seem to always get up to 220*. I run snowmobiles all winter and those are two strokes, why would it not be hard on them and hard on nitro engines? I am just curious to some ideas, I got a great os speed that I am running and I am getting a bit worried about hurting it.
I ususlly see 200F quoted as minimum temp for running. At some ambient temps thats hard to maintain - this is where you use something like tin foil to block cooling air so the engine can keep the heat and stay above this minimum temp. Even if you're tuned perfectly, running at 155F is going to load the rod excessively and cause premature wear to the pinch zone. Even if you're preheating to start, if you can't maintain that min temp while running, you're wearing parts prematurely, pinch will disappear quickly.
Two stroke engines (motorcycles, snowmobiles) have less taper in the piston/cylinder fit and use rings, not pinch, to provide seal. This is why they don't have probs running at low temps given that they're tuned correctly.
12-05-2008, 09:30 PM
#26
Tech Regular
iTrader: (7)
Somehow this seems to have turned into tuning for hot and cold temps. Def need to know what to do for ambient temp changes, but what's bad about running a nitro engine in the cold is if the engine can't get to some minimum operating temp so piston/sleeve expand enough, the rod is getting hammered, slamming into a tight pinch all the time since P/S haven't expanded proper amount.
I ususlly see 200F quoted as minimum temp for running. At some ambient temps thats hard to maintain - this is where you use something like tin foil to block cooling air so the engine can keep the heat and stay above this minimum temp. Even if you're tuned perfectly, running at 155F is going to load the rod excessively and cause premature wear to the pinch zone. Even if you're preheating to start, if you can't maintain that min temp while running, you're wearing parts prematurely, pinch will disappear quickly.
Two stroke engines (motorcycles, snowmobiles) have less taper in the piston/cylinder fit and use rings, not pinch, to provide seal. This is why they don't have probs running at low temps given that they're tuned correctly.
I ususlly see 200F quoted as minimum temp for running. At some ambient temps thats hard to maintain - this is where you use something like tin foil to block cooling air so the engine can keep the heat and stay above this minimum temp. Even if you're tuned perfectly, running at 155F is going to load the rod excessively and cause premature wear to the pinch zone. Even if you're preheating to start, if you can't maintain that min temp while running, you're wearing parts prematurely, pinch will disappear quickly.
Two stroke engines (motorcycles, snowmobiles) have less taper in the piston/cylinder fit and use rings, not pinch, to provide seal. This is why they don't have probs running at low temps given that they're tuned correctly.
12-06-2008, 07:37 AM
#28
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
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
Somehow this seems to have turned into tuning for hot and cold temps. Def need to know what to do for ambient temp changes, but what's bad about running a nitro engine in the cold is if the engine can't get to some minimum operating temp so piston/sleeve expand enough, the rod is getting hammered, slamming into a tight pinch all the time since P/S haven't expanded proper amount.
I ususlly see 200F quoted as minimum temp for running. At some ambient temps thats hard to maintain - this is where you use something like tin foil to block cooling air so the engine can keep the heat and stay above this minimum temp. Even if you're tuned perfectly, running at 155F is going to load the rod excessively and cause premature wear to the pinch zone. Even if you're preheating to start, if you can't maintain that min temp while running, you're wearing parts prematurely, pinch will disappear quickly.
Two stroke engines (motorcycles, snowmobiles) have less taper in the piston/cylinder fit and use rings, not pinch, to provide seal. This is why they don't have probs running at low temps given that they're tuned correctly.
I ususlly see 200F quoted as minimum temp for running. At some ambient temps thats hard to maintain - this is where you use something like tin foil to block cooling air so the engine can keep the heat and stay above this minimum temp. Even if you're tuned perfectly, running at 155F is going to load the rod excessively and cause premature wear to the pinch zone. Even if you're preheating to start, if you can't maintain that min temp while running, you're wearing parts prematurely, pinch will disappear quickly.
Two stroke engines (motorcycles, snowmobiles) have less taper in the piston/cylinder fit and use rings, not pinch, to provide seal. This is why they don't have probs running at low temps given that they're tuned correctly.
These two post are dead on.........
