Qs nitro vehicle
05-16-2010, 05:06 PM
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Qs nitro vehicle
ok i have nitro truck and cars and the other day me and my brother was bashing and we took the hose off that goes to the exhaust pipe and they was running alot quicker and stayed alot cooler so my Q is has anyone ran theirs like that before and will that cause any problems? i have the axail 28 in my mgt and they motor got to 260 without overheating but if i put the hose back on the exhaust i could not get to 220 without overheating any ideas? i dont have air leaks because i just sealed my engine the other day and checked my hoses
06-04-2010, 01:15 AM
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RE: Qs nitro vehicle
Erm.... you removed the hose that runs from the exhaust pipe to the fuel??
Well - what you did was remove the force-feeding of fuel into the engine.. the exhaust provides pressure to the fuel tank, pushing the fuel through, in cooperation with the engine's natural suction.
On a smaller engine, you wouldn't even be able to remain running...
it was running quicker because you essentially leaned it out. When tuning - leaning out will make more power, but shorten the life of your engine.
The reason it was running hotter is the same - running leaner will get the temps up because the fuel acts to cool the engine as well - two strokes are designed to have a significant amount of unburnt fuel pass through, when compared to 4 stroke, or "real car" engines. The fuel in a nitro car acts as coolant and lubricant all in one.
With that said - you should put that hose back on, and tune your car properly. 220 seems a little rich for the axial 28 - you can get that baby to purr all day long at 250.
frankly - you dodged a bullet.. i wouldn't run that engine like that for long - you're fortunate that its a larger engine and has enough suction to draw in the fuel by itself... a .21 or smaller would barely run if at all, and if you tried to throttle it up to force it, you'd be running way too lean.
Well - what you did was remove the force-feeding of fuel into the engine.. the exhaust provides pressure to the fuel tank, pushing the fuel through, in cooperation with the engine's natural suction.
On a smaller engine, you wouldn't even be able to remain running...
it was running quicker because you essentially leaned it out. When tuning - leaning out will make more power, but shorten the life of your engine.
The reason it was running hotter is the same - running leaner will get the temps up because the fuel acts to cool the engine as well - two strokes are designed to have a significant amount of unburnt fuel pass through, when compared to 4 stroke, or "real car" engines. The fuel in a nitro car acts as coolant and lubricant all in one.
With that said - you should put that hose back on, and tune your car properly. 220 seems a little rich for the axial 28 - you can get that baby to purr all day long at 250.
frankly - you dodged a bullet.. i wouldn't run that engine like that for long - you're fortunate that its a larger engine and has enough suction to draw in the fuel by itself... a .21 or smaller would barely run if at all, and if you tried to throttle it up to force it, you'd be running way too lean.
06-04-2010, 01:57 AM
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RE: Qs nitro vehicle
thank you for your input but also i cant get the engine to go over 220 without over heating i dont have any air leaks but if i put the hose back on then 220 will over heat the engine and its pretty much new less than a gallon so can you tell me why that is? i really would like to know.. maybe i just need to replace the piston and sleeve what do you think?
06-04-2010, 10:34 AM
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RE: Qs nitro vehicle
well - what do you mean by overheating? I'm assuming its showing some behavior that makes you say that.
It's likely a bad tune.. you can take two engines that are running 220 degrees, and the one with an okay tune will be running fine, but the other one with a bad tune will be sputtering, popping, or have uneven spots in the throttle delivery, etc...
everything from your mixture set screw to the HSN and LSN can affect the way the car runs independantly from eachother, and yet all need to be tuned together to get a decent running truck.
got any vids of what it sounds like when its acting up?
It's likely a bad tune.. you can take two engines that are running 220 degrees, and the one with an okay tune will be running fine, but the other one with a bad tune will be sputtering, popping, or have uneven spots in the throttle delivery, etc...
everything from your mixture set screw to the HSN and LSN can affect the way the car runs independantly from eachother, and yet all need to be tuned together to get a decent running truck.
got any vids of what it sounds like when its acting up?
