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Old 09-02-2010, 12:42 PM   #31
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You can still have smoke and be too lean. The smoke coming out might be because its extra rich after refueling. After i refuel i get lots of smoke, not just a normal amount. And then after a couple blips it cuts back down to where it should be in terms of smoke. The smoke also changes based on the oil % you are running in the fuel. But some smoke is better than no smoke, thats for sure


oh well when i take it off the track my engine always runs at 230 to 245 .
yea i know the extra smoke does come out when refueling.
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Old 09-02-2010, 12:49 PM   #32
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oh well when i take it off the track my engine always runs at 230 to 245 .
yea i know the extra smoke does come out when refueling.
Well thats good, in this area i tend to run in the 260s range, but thats just what the engine seems to like. Go engines seem to like the hotter part of the spectrum for some odd reason. Ahh well, its all good, as long as we are having fun
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Old 09-03-2010, 07:41 AM   #33
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I allways thought and have personally found the engine leans out after re fueling not richens.. Many people think it richens as they have just filled there tanks but as i understand it thats not the case just a common missunderstanding. The car will bog down a little on the 1st lap or two because you dont have enough pressure over the fuel to push the fuel towards the engine therefor it leans out


It is a bit like when using a presurized oil filler like for car or marine gearboxes.. if the unit is full of oil you cant get much air pressure to push the oil as there is no room for the pressure to build up and what does is a very small percentage of the overall volume and wont do much


Here is something i copied from another site that explains it better perhaps


If you've done much gas racing, you've probably encountered the dreaded lean bog that occurs right after a pit stop with a full tank of fuel. Right after the tank is filled, for about the next 3 or 4 laps the engine sags (lean bogs) when accelerating off of tight right-hand corners. On most tracks this happens when accelerating onto the straight. Seemingly, the lean bog magically goes away after a few laps but sure enough, after the next pit stop, it frustratingly returns-slowing lap times for several laps once again.
The key to eliminating full tank lean bogs is pressure tube position or adding a pressure reservoir as shown.

To solve this frustrating issue, it's important to understand what's causing it.
Here's the scoop. As the throttle is released entering a turn, the pressure in the tank is now greater that the reduced pressure in the pipe. When the tank is full, some of the fuel sloshes up into the pressure line. The centrifugal forces encountered in a right hand turn further pulls the fuel into the pressure line, causing reduced pressure in the tank. When the throttle is cracked open to accelerate, the engine goes lean because of this reduced tank pressure and hence the dreaded lean bog occurs. The reason it only lasts for a couple of laps is first, as the fuel level goes down in the tank it's less likely to slosh as much into the pressure line and second, as the fuel level goes down there is a larger open space in the tank that's pressurized, maintaining adequate pressure long enough to prevent the low pressure lean bog problem. (If your exhaust system is mounted on the left side, as with some of the latest monster trucks, then this phenomenon will occur in left hand turns.) ,




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Old 09-04-2010, 08:16 AM   #34
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Thank you for all your replies!

I'll try to tune it again and we'll see what happens. It doesn't have too much smoke and for sure is not being flooded at the bottom so i'll try richening it up a little bit.

Also, have you heard about stopping the engine by dropping fuel on the pipe? If it's true what do you do to prevent fuel gun from dropping fuel on the pipe right after refueling? I was thinking about adding an extra spring what should make the gun to close faster and tighter - what do you think?

Last edited by Donat; 09-04-2010 at 10:01 AM.
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Old 09-05-2010, 12:43 AM   #35
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I run a ninja...What is a flameout?
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Old 09-05-2010, 02:56 AM   #36
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Quote:
Originally Posted by rc skyline View Post
I allways thought and have personally found the engine leans out after re fueling not richens.. Many people think it richens as they have just filled there tanks but as i understand it thats not the case just a common missunderstanding. The car will bog down a little on the 1st lap or two because you dont have enough pressure over the fuel to push the fuel towards the engine therefor it leans out


It is a bit like when using a presurized oil filler like for car or marine gearboxes.. if the unit is full of oil you cant get much air pressure to push the oil as there is no room for the pressure to build up and what does is a very small percentage of the overall volume and wont do much


Here is something i copied from another site that explains it better perhaps


If you've done much gas racing, you've probably encountered the dreaded lean bog that occurs right after a pit stop with a full tank of fuel. Right after the tank is filled, for about the next 3 or 4 laps the engine sags (lean bogs) when accelerating off of tight right-hand corners. On most tracks this happens when accelerating onto the straight. Seemingly, the lean bog magically goes away after a few laps but sure enough, after the next pit stop, it frustratingly returns-slowing lap times for several laps once again.
The key to eliminating full tank lean bogs is pressure tube position or adding a pressure reservoir as shown.

To solve this frustrating issue, it's important to understand what's causing it.
Here's the scoop. As the throttle is released entering a turn, the pressure in the tank is now greater that the reduced pressure in the pipe. When the tank is full, some of the fuel sloshes up into the pressure line. The centrifugal forces encountered in a right hand turn further pulls the fuel into the pressure line, causing reduced pressure in the tank. When the throttle is cracked open to accelerate, the engine goes lean because of this reduced tank pressure and hence the dreaded lean bog occurs. The reason it only lasts for a couple of laps is first, as the fuel level goes down in the tank it's less likely to slosh as much into the pressure line and second, as the fuel level goes down there is a larger open space in the tank that's pressurized, maintaining adequate pressure long enough to prevent the low pressure lean bog problem. (If your exhaust system is mounted on the left side, as with some of the latest monster trucks, then this phenomenon will occur in left hand turns.) ,




Dave
The fat running of an rc car engine at startup or after refueling is due to the fuel being cold, thus denser, as the fuel heats up from the pressure line heat the molecules expand giving you less fuel to air and the engine runs right, after refueling the cold gas in the engine causes it to run rich for half a lap...
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Old 09-05-2010, 04:32 AM   #37
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