RC Nitro Engine Tips

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RC Nitro Engine Tips

Nitro Engines Database



RC Nitro Engine Tuning Tips

This page is dedicated to answering frequently asked questions about nitro engines and how to tune them. First, may I suggest you download a copy of the free e-book "Secrets of Nitro RC Cars." It contains a section on how to tune and troubleshoot nitro engines.

Maximum Engine Power
Running Temperature
Overheating Problems
Overheating Problems Despite a Rich Setting
Too Lean
Too Rich 
Glow Plugs

Maximum Engine Power

To get the maximum power from a new engine, just follow these basic tips:

1. Ensure no air leaks - Make sure there are no air leaks by using high-temperature gasket or silicon sealants. Apply to areas such as the carburetor to the engine block, the exhaust manifold to the exhaust port of the engine block, and the back plate or pull-start mechanism against the engine block. 

2. Proper motor break-in procedure - Run at least 3 tanks of fuel through the new engine, maintaining temperatures between 140 - 160 degrees. Vary the speed of the engine while running, but avoid going for top speed. Keep the body off during the break in process to keep the engine cool.

3. Proper running temperature - Basic guide is to keep engine temperatures between 200 - 210 degrees. But for more power you can lean out the engine a little more, and keep the temperature between 200 - 225 degrees.

Running Temperature

Hello i have a bv1 and it has the os .15 engine. the running temp is 150F. what i cant seam to do is take of quick. it will always gurgle and then go. do i need to make it run hotter or should i tune the low end needle. i have seen peoples running temps at 230F is this alright. should i lean the high end needle more or lean the low end. im not sure if 150F is a low temp. is it? 
any help would be great. thanks lachlan

Answer: Hi Lachlan, 150F seems to be on the cold side. Gurgle (a rich sound) may indicate a "rich" low end. Tune the low end, then readjust the high end. With the temperature, I myself just use the spit test. If spit sizzles when put on the cylinder head fins, then it is too hot. - Joel

Overheating Problems

HI i have just bought a Traxxas 4tec nitro and am shocked at the speed of this thing but i am concerned by what others are telling me about it such as over heating problems also that the engine wont last if that is the case what other engine can fit on and will it be just as fast. thanks andrew 

Answer: Hi Andrew, If you follow the tuning guide that comes with your engine you should be ok. Just make sure that the engines get enough cooling air to prevent overheating (usually cutting holes in the windshield). Also tune the engine carburetor to be on the slightly "rich" side. - Joel

Overheating Problems Despite a Rich Setting

joel maybe you my have answer i have a thunder tiger tsn-4 with .15 have probs with over heating no matter how rich i have the fuel. have the car at max rpm tune in to max rpm then rich it 1/8 of turn as i have been told runs great but will only go through about 1/2 a tank then will stop motor to hot with or without the body on getting very pissed off with it have taken it back to place i got it from they so it ok can you suggest anything mate. waiting your reply. thanks joe

Answer: Hi Joe,

I used to have those motor problems when I first started, but over time it becomes easier to troubleshoot.

I would take a guess and that the problem is either:

1. There is an air leak somewhere.
2. Maybe the low end needle setting (if it has one) is set too lean.

Just keep in mind, a hot engine is one that has too much air and not enough fuel in the mixture entering the engine. So check anything the might increase air (air leaks) or decrease fuel (dirty fuel, pinched air hose, weak backpressure coming from the tuned pipe). - Joel

Too Lean

Here are some symptoms of an engine that is running too lean:

1. Dies or "flames out" at full throttle.
2. The glow plug wire or "element" turns white.
3. A drop of water or spit on the engine heat immediately sizzles. Too hot.
4. Dies while just idling.
5. Dies while accelerating from idle. Note this can also be caused by a rich engine.

Too Rich

Here are some symptoms of an engine that is running too rich:

1. A lot of blue smoke from the exhaust pipe.
2. A lot of unburned fuel exiting the exhaust pipe.
3. Idles properly, but bogs down an dies when the throttle is full applied.
4. Never reaches full top speed.
5. Engine temperature is too cold (e.g. below 200 F degrees)

Glow Plugs

Glow plugs are very important to the performance of your engine. You can also read your glow plugs to determine if you are running too rich or too lean.

A brand new glow plug has a wire or filament that is shiny. If after running the wire is still shiny and the bottom of the plug is wet, then you are running too rich. You are probably getting only 85% of the maximum engine power.

If the wire turns starts to turn gray, and the bottom of the filament is slightly wet, then you are almost near the peak engine power.

Once you have a gray wire, and the bottom of the plug is dry, you are at 100% maximum power.

Once the glow plug wire starts to distort, you have exceeded the maximum power and are running too lean. Adjust to a slightly rich setting.

Hot plugs are used for hot summer days, while cold plugs are designed for cold "winter" days.

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