This text is machine translated.
What was the distinguishing feature of an off-road combustion model car?
An off-road combustion model car is best equipped for the rapid drive on uneven and loose surfaces. The reason for this is the following properties:
1. Large wheels with handy profile
To master the ground waves, terrain transitions and potholes perfectly, off-road car models are equipped with unusually large wheels. In combination with soft tires, which offer maximum grip even on loose surfaces with their rough profile, the drive power can be converted perfectly into propulsion.
2. All-terrain chassis
To ensure optimum contact with the ground when accelerating, braking or cornering, the chassis are designed for extreme loads. Individually suspended wheels, extremely long spring travel and progressive shock absorbers equalize even the most violent unevenness playfully and ensure that the chassis plate does not break through to the ground when jumping.
3. Powerful drive
Whether it is a high-revving nitro engine or a high-capacity petrol engine, the drive concepts are always designed in such a way that the driver has more than sufficient power. In combination with four-wheel drive, this results in an unbelievably light-footed acceleration on top speed. And in vehicles with rear-wheel drive, a sensitive handling of the throttle is sufficient to take long-drawn curves in spectacular draft-glass pins.
4. Core sound
In an off-road combustion model car, power and sound go hand in hand. This means that the driver receives an impressive audible feedback on how the gas control commands are implemented in the model. On the other hand, the spectators also register very quickly at the engine noise, in which section of the road the driver pulls the gas fully through.
Electric or combustion drive, where are the advantages and disadvantages?
It is undisputed that electric drives as well as combustion drives have their advantages and disadvantages. For a better overview, we have summarized the main arguments in a table:
| Advantages: | Quiet operating sound | Long driving times thanks to low fuel consumption. |
| No combustion residues or oil on the vehicle. | The duration of use is limited only by the tank volume or fuel supply. | |
| Easy to use. | No expensive drive batteries and chargers required. | |
| Simple mechanics, because the brake function is realized via the motor. | Ready to use immediately after refueling. | |
| Reverse drive function possible via drive controller. | Engine sound matches the power output. | |
| Disadvantages: | Travel time limited to battery capacity. | Operating noise is sometimes perceived as loud and unpleasant. |
| Additional batteries are required for longer driving times. | Combustion residues or oil on the vehicle. | |
| Battery charger required. | Carburetor adjustment requires expertise and experience. | |
| Before use, the drive batteries must be charged. | Mechanics are more complex, because disc brakes are used. | |
| Engine sound does not match performance. | Reverse gear only possible via a manual gearbox. |
As can be seen from the overview, both drive types have advantages and disadvantages. Ultimately, every user has to decide for himself whether a combustion or an electric off-road model car is the better choice.
Where can ich drive with an off-road combustion model car?
With full throttle through the gravel pit makes a good mood!
Due to the not insignificant noise emission, it is unfortunately not so easy to find a suitable terrain for operating an off-road combustion model car. The undisputed best place is and remains the specially built race track of an association.
Many clubs offer the possibility to use the route as a guest driver for a small fee and to gain the first experience in dealing with a combustion-engine car model. Club membership is therefore not necessary, but nevertheless one has the possibility to profit from the know-how of the club members.
In addition, driving on a delimited racetrack is much more demanding than driving on a large open area without specific direction guidelines. Finally, the model car should be moved as close as possible to the ideal line. Even slight deviations from the ideal line mean that the next curve will not be optimally crossed, was immediately recognizable to the driver. The emotional handling of gas and steering is learned intuitively.
If you don't have a club in the vicinity, you can of course also search for a suitable area, such as a sand or gravel pit. However, the owner/operator should be asked for permission before using the model for the first time. In this context, it is also possible to clarify at which times and in which areas the site may be used. It should also be clarified, however, that the operation of a combustion model car does not violate any provisions of environmental, nature and animal protection.
Which fuel is used to drive off-road combustion model cars?
Off-road model cars in the scale 1:6 or 1:5 are usually driven with a petrol engine. The fuel used for these engines is a commercially available mixture of two-stroke oil and super petrol with a ratio of 1:25, which is available at every petrol station.
If the engine is new and needs to run in, it is recommended to use 2-stroke mineral oil. When the engine has burned 5 – 10 l of fuel, it is possible to switch to full synthetic 2Takt oil, with some petrol engines the mixing ratio can be changed to 1:50.
For further information on the fuel mixture ratio, refer to the documents of the model vehicle.
For petrol model engines, there is fuel at the petrol station.
Methanol fuel is available in a wide variety of containers.
Off-road model cars on a scale of 1:8 are usually operated with glow-ignition engines, which are also referred to as nitro engines or methanol engines. The special feature of these engines is the operating principle, which is based on a diesel engine. Instead of a spark plug, a glow plug is used in these engines, which must be pre-annealed before starting.
These engines require methanol as fuel, which is mixed with synthetic or castor oil for lubrication andnitromethane for ignition improvement or performance enhancement.
This fuel is completely mixed in different containers and with different nitro shares offered.
Our practical tip:
A fuel with a 15 – 16% nitromethane content is perfectly sufficient for beginners. A higher percentage of nitromethane makes the fuel unnecessarily expensive and increases the load on the engine. The associated performance gain is primarily of interest to competition drivers.
Important:
The combustion of methanol and nitromethane produces acid combustion residues which must be neutralized with special "after-run oils". Otherwise, there is a risk that the crankshaft ball bearings will start to rust.
Was it necessary ich when operating off-road combustion model car
Important:
The operation of model cars with combustion engines is associated with a certain risk potential. For this reason, children and young people should only operate a model with a combustion engine under the supervision of an adult.
The engine, the silencer or other vehicle parts such as the brake discs can become very hot when the vehicle is in operation. This poses an acute risk of burns. For this reason, allow the model to cool down to ambient temperature before carrying out installation or adjustment work.
- Let engine run
Probably the most important point when operating a combustion car model is the fact that a new engine has to run in.
Experienced engine engineers in the automotive industry say quite clearly that all rotating or sliding parts of a new engine are rough and uneven when you look at them more closely. There are also the manufacturing tolerances and deformation through thermal and mechanical load.
This clearly makes it necessary for a model engine to allow this engine to run in so that the moving parts can be adjusted to each other. The following points must be observed:
• Low speed
• very rich fuel/air mixture
• the running-in time with pauses interrupt
• the engine to run in for at least 30 minutes
After this time, the engine can be made leaner so that the vehicle model can be operated. The final running in process may take several hours depending on the motor and the fuel. During this time the drive should always be operated with a rich carburettor setting and only gradually feel your way to maximum performance.
A drive unit with a rich carburettor setting will, under certain circumstances, not achieve maximum potential performance. However, it will not suffer any damage as a result. An engine with too lean a setting will overheat very easily and can cause considerable damage within a very short period of time.
For Nitro motors, the running-in process is extremely important.
Operation only with air filter
Without air filter, it is not possible in the terrain.
During a wild ride through the terrain, dust and dirt are stirred up in large quantities by the rough-studded tires. That is how it should be. However, the combustion engines are very sensitive to dirt that enters the engine compartment via the air drawn in. The dust-grain-sized stones then act like emery paper and destroy the running surfaces of the piston and the ball bearings within a very short time.
For this reason, air filters are an absolute must! To increase the filter effect, the paper or foam filters are still soaked with a special air filter oil. Even the finest particles are filtered out of the air and the engine thanks to this with a long service life.
Adjust carburetor correctly
The driving pleasure with an off-road combustion car model stands and falls with the setting of the carburetor. The best model with the most powerful engine will not spread any driving pleasure, if the engine only reluctantly gets to speed due to a wrongly adjusted carburetor and the performance breaks down completely at full throttle.
For this reason, you have to familiarize yourself with the technology and the function of the carburetor adjustment screws. Only then will the driver be able to adjust his engine perfectly, in order to maintain a reliable engine running in every speed range.
The maximum motor power is set with the full throttle adjusting screw (1) and there is a separate idle speed adjusting screw (2) for idle speed.
The model vehicles are usually supplied with extensive operating instructions, which also show the exact adjustment of the carburetor needles. But regardless of this, it is important for every user to develop a certain sensitivity for the adjustment of his motor.
Classic 2-needle carburetor of a nitro engine.
Warm up the engine
Let the engine run warm first, then apply full throttle.
If you want to enjoy your model engine for a long time, you can give it enough time to reach the operating temperature. When the engine is warm, the lubricating film of the oil is stable and the carburetor setting fits perfectly, since the carburetor needles are always adjusted when the engine is warm. Now you can safely apply full throttle and the motor will quickly implement the speed changes.
If full throttle is already applied when the engine is cold, a heavy-duty lubricating film has not yet been developed. Increased engine wear up to the major engine damage can be the consequences.
Not too much at the carburetor screws
If a model engine has always run well and suddenly does not start or runs unsmoothly, it is most likely not due to the carburetor setting. Experience has shown that if you now turn the setting screws for idle speed and full throttle, it only makes it worse.
It is better to look for possible other causes, such as a leaking petrol hose, dirt in the fuel system or a faulty ignition/spark plug or glow plug.
Our practical tip:
Once you have found the perfect setting of the carburetor adjustment screws, you should make a detailed note of the setting. To do this, turn each adjustment screw completely in as far as it will go and count the turns. If you¼ were able to screw in the adjustment screw by e.g. 2 turns, open the screw again by exactly this value so that the adjustment screw is back on the originally perfectly fitting setting value. Carry out this procedure with the full throttle and idle speed adjustment screws and note down both values.
If you later have to disassemble the carburetor for service or cleaning and remove the adjustment screws, you can set the carburetor back to the perfect values without much effort using the values noted.
FAQs on the topic of off-road combustion model cars
What was the exact meaning of fat or lean carburetor setting?
A "fat" setting is used when the fuel content is high in the air sucked in by the engine. If the carburetor setting screws are changed so that the engine receives less fuel, this is referred to as a "lean" setting. Since the model engine also receives the oil for lubrication via the fuel, it is dangerous to operate the engine too lean. Poor lubrication can result in major engine damage. Therefore, it is better to set the carburetor to "richer".
Where do you get the fuel for combustion model cars her?
You get the fuel for a model with petrol engine at every petrol station. It is important to pay attention to the mixing ratio. Fuel for glow-ignition engines is obtained at Conrad Electronic branches or at the local model construction dealer. Since the fuel components are toxic substances, the charge is only made from 18 years of age and upon presentation of the ID card.
My 1:8er model car with nitro engine smokes very strongly. Was there anything broken?
No, quite the opposite. The strong exhaust smoke indicates a rich carburetor setting. This means that the fuel proportion in the gas/air mixture is very high. This setting is good if the engine is still new. Over time, the carburetor can be made leaner, then the exhaust will not smoke so much anymore.
How can ich check the function of a glow plug?
Simply connect the glow plug in the removed state to a PowerPanel or a glow plug connector. In the hollow hand you can see very well whether the spiral glows orange to light red. However, caution is required as the glow plug will become very hot in a short time.
Can a combustion model car be put into operation without any prior knowledge?
Without prior knowledge, it becomes difficult, as you can do a lot wrong. Either you read in the matter and use the necessary basic knowledge, or you can turn to a model builder who already has extensive knowledge in the handling of model engines.