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Old 10-27-2002, 05:32 PM   #1
cox
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Angry Please Help!!!!! Engine tuning for dummies,


i have a problem with my novarossi engine, it always stalls. it runs fora few laps then the engine dies. i check the temp once in a while and there is no problem its just running 95 to100 deg. it frequently dies when my throtle is in the mid section and when i go to full throtle the engine dies please help.
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Old 10-27-2002, 07:40 PM   #2
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95-100 degrees! my car doesn't even get that cold the second it fires up. When mine fires up, it is already165.


wait, I think I figured it out, that is in Celsius no isn't it.

In that case, it is still a little cold, and from the sounds of it, your cars high end is either too rich or too lean. Without running it, that is my only observation that I can say with some precision.

There are soo many variables that affect microengines and it would be helpful, if you tell us the type of engine, the percentage of nitro, the glow plug, the weather and temperature, the humidity, and the size of your track that you race on.
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Old 10-27-2002, 07:42 PM   #3
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Sorry, I meant to put this in the last post.

Your problem seems to be the high end needle settings or your nitro percentage/plug type. so make sure you give these to us.
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Old 10-28-2002, 07:47 AM   #4
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well this is my engine, novarossi 3port s12, glow plug i use is #5 nitro percentage 25%. the weather temp is 33 to 35 deg C. the size of our track were 30 meters stretch and some some twist n turns that is quite small. hope you can help me with the tunning thanks in advance
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Old 10-28-2002, 08:53 AM   #5
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Quote:
Originally posted by cox
well this is my engine, novarossi 3port s12, glow plug i use is #5 nitro percentage 25%. the weather temp is 33 to 35 deg C. the size of our track were 30 meters stretch and some some twist n turns that is quite small. hope you can help me with the tunning thanks in advance
Ok, for 25% nitro, a number 5 plug is a little harsh to the engine especially in a weather condition (high temp and humidity) like ours.

Using too high nitro percentage with a hot plug and with the stock / standard 0.3 mm head shim (I assume) would cause detonation. If I were you, I'll check signs for it. Open your plug and observe the top of the piston and see if it looks rough / pitted or sand-blastered. Those are signs that your engine has undergone detonation. Another tell tale sign is to hear the engine with your ears. If you hear a crackling / pinging sound like an fryed egg, then your engine is detonating.

I suggest going with a colder plug. Number 6 or even 7 might do the trick. That may also cure your engine stalling problem.

If you mention that you have temperature problems, then I would advice you to add some shims (additional 0.2 to 0.3 mm more than the existing 0.3 mm shim). This will lower the engine compression and cool the engine down.

After changing the plug to a colder one, start the engine and make sure that you get a constant engine idle for about 15 to 20 seconds WITHOUT the engine RPM fluctuating.

If the engine RPM drops down after a good rev, your low end needle may be set a little rich. Lean it by turning the low end needle clockwise.

If your engine RPM goes higher and higher after a good rev, your low end needle is a little lean. Richen it by turning the low end needle anticlockwise.

Remember when changing the setting, do it little by little (i.e. 1 hour adjustments).
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Old 10-28-2002, 11:04 PM   #6
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i too is having problems with my engine... i have a fantom fr .15 engine.. my car stalls when i press on the brake. people told me to check if the thing closes all the way (notice i dont know the terminology yet) and i did and it doesnt close all the way.. another thing they told me to do is check the small needle or screw on the carb.. not the main one but the lil one... theres one lil thing that pops out right next to the filter (have to use a hex key for this one) and one that connects to the reciever... which one do i mess with and which way do i turn? please help...thanks...
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Old 10-29-2002, 03:11 AM   #7
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Its usually easier to go down to 20% nitro in my opinion. Plenty guys like to mess with nitro percentage, but problems like these occur. This problem, may not be necessarily based on nitro %, but I find that most people don't know how to correctly go about using higher percentage fuel. 25 is good, but too many people try 30+ in my opinion, b/c few have the knowledge that initialD has.

If it is humid where you race, I would suggest the #7, otherwise a six would be better. But realize, that this will raise your engines temps. Different fuels and plugs can change an engines temp by 20 degrees (farenheit, sorry )

Your high end needle setting was probably set to lean because your low end needle was a shade on the rich side, so this would compensate for the rich low end by giving more power in the lower rpm range. However, when going just before full throttle, that is when fuel demands are at its highest, so it makes obvious sense that your cutting out during heavy acceleration.

If it were your low end needle settings, then you wuold see your engine cutting out at almost any point in the rpm range. This is because a lean low end needle setting gradually overheats an engine anywhere after the three minute mark in a race generally, depending on how lean your carb is.

Just remember that if your settings were your problem, then it is quite possible your plug, fuel, head shim combo caused you to resort ot these settings. However, a problem like this could be many different things and try what you think is best.
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Old 10-30-2002, 04:04 AM   #8
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General rule of thumb

The hotter the engine runs the hotter the plug you need.

The colder the engine runs the colder the plug you need.

This seems to be a misconception with glow plugs. When an engine is running hot (considering top/bottom end are not lean) you need to switch to a hotter plug. Why? Its because the engine is running too lean to keep the colder plug lit!

If your talking celius, this sounds like the correct temp spec for the Novarossi S3. We run them here at about 100deg C and push them up to about 110C to 115c during major meets.

Knowing Novarossi engines, I'd say your problem lies with the bottom end!
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