Intro: Nitro RC Cars
Owning and operating a nitro powered radio controlled car or truck adds an element of excitement and realism to this hobby above and beyond that provided by the electric RC counterparts. Unfortunately, it also poses some unique challenges. The one question that is posed to me the most often is 'how do I start a gas powered RC car'?
Well, first of all, you need to assemble a few necessary items. These can be obtained either individually, or purchased as a package with or without your radio controlled car or truck. You will need the correct nitro fuel, a glow igniter, batteries for your radio transmitter and receiver, and a small screwdriver.
Have your glow igniter fully charged and ready to use. Make sure you have installed batteries in your controller (transmitter) and the car's on board receiver. Verify that they are functioning properly by operating the steering, throttle and brake. After all, you want to be able to control your RC car once it is running! Fill the car's fuel tank with the proper nitro fuel. Be careful fuel is extremely flammable and toxic! Check with your engine's manufacturer or your local hobby shop to make sure you are using the recommended nitro mix. 20% is the most popular. OK? Now we are ready to fire her up.
Clip the glow igniter to the glow plug located in the top of the engine cylinder head. Rotate the engine by whatever means your car or truck uses such as manual pull recoil, on board electric starter, drill operated shaft starter, or portable starter box. You may have to 'choke' the engine to initially supply fuel to the carburetor. You can easily do this by placing a finger over the exhaust outlet. Watch for fuel movement through the fuel hose so you know when fuel has reached the carburetor. You don't want to flood the engine!
Once the engine has started and is running smoothly, you can remove the glow igniter. Drive easy for a few minutes until the engine warms up a little. After warm up you may find it necessary to adjust the carburetor high speed needle, low speed needle, or idle speed set screw to maximize performance.
This might all seem intimidating to you, but it really isn't hard to learn with a little practice and patience. The sound of that high performance nitro engine springing to life makes it well worth the effort!
sources www.hobbiedown.com and actionvillage.com
Step 1: How to Drive You Gas RC Car.
I no most people think its easy to drive but most do not.
Realize that your controller works just like the steering wheel on your regular car. When you move it to the left, your RC car moves to the left and when you push the controller to the right, your car moves to the right.
Drive as fast as you can the first few times you take your RC car onto a new track. This will help you get a feel for the track without worrying too much about making a mistake.
Stick to the middle of the track instead of trying to hug the edges. Your lap times might not be as good, but at least you won't drive your RC car right into one of the track barriers.
Look for lines or the areas of the track where more experienced racers drive their cars. This should give you an idea on how to lower your lap times.
Draft with other cars just as you would if you were racing NASCAR instead of driving an RC car. Not only can you increase your speed, but you can also see where other cars are running and what spots drivers are avoiding.
Be consistent any time you drive your RC car. The more time you spend racing and practicing, the better you'll get.
ive but most dont.
Step 2: Gas Rc Car Safey
Safety Issues and Rules for Responsible RC Car & Truck Operation
Be a safe, courteous, and responsible RC car or truck owner and operator. Protect yourself, those around you, and your RC vehicles by using common sense and following certain guidelines for safe use of radio controlled cars, trucks, motorcycles, tanks, bulldozers, and other RC ground vehicles.
Control Your Controller
Before you run your RC: Controller on first, vehicle on second. After you run your RC: Vehicle off first, controller off second.
Choose a Safe Area to Operate Your RC
Choose a safe, open area to operate your radio controlled vehicle. Avoid people and busy streets.
Check Your Frequency
Check your frequency and make sure no one in your operating area is using the same frequency at the same time you are.
Check for Obstacles Before Operating Your RC
Survey the area that you will be driving in and make sure it is clear of undesired obstacles... i.e. stumps, large rocks, puddles of water, or other obstructions.
Avoid Spinning Wheels
Do not pick up your vehicle while the tires are still moving.
Handle and Store Nitro Fuel Safely
Nitro fuel is highly flammable. Avoid open flames -- including smoking -- around nitro containers. Mark your container for identification.
Step 3: Nitro RC Operation and Maintenance
Nitro RC Operation and Maintenance
A nitro RC has many more parts than most electrics. There are also specific operational and maintenance requirements from engine tuning, to break-in, to after-run maintenance. Learn how to keep your nitro RC glow engine at peak performance levels. And when your nitro engine won't run, do some troubleshooting to isolate and fix the problem.
Nitro Troubleshooting @
Nitro Engine Break-in Procedure
Proper nitro engine break-in is critical for long-lasting performance of your RC. Every new nitro engine should undergo a break-in procedure. If you do nitro engine break-in properly, the up-keep on your RC vehicle is less costly than if the procedure is done hastly and incorrectly. Be patient.
Adding After-Burn Oil
After running your RC for a while you have to perform after-run maintenance. Part of that after-run maintenance includes lubricating the pistons and all the internal parts by adding after-burn oil to the engine cylinder head.
Step 4: Carb Ajusting.
How does the carburetor work and how do I adjust it?
We got the theory part of the engine under control. We can't really tune a piston or adjust a crank-shaft, at least not in your every-day engine maintenance and adjustment. So without further delays lets dive into the 2nd phase of this project& The Carburetor. What good is a 1.2 HP engine if you can't keep the dam thing running? That's exactly my point, it does not matter how little horse power your engine has, if it can stay running for the entire duration of the main then you will have a real good change to at least get one of the top three positions. They say that before you can win a race -first you must finish. The first part of finishing a race it to have a well tuned engine. In this article we will go over how a carburetor works and how to adjust it. Without any further delays lets get busy!
The carburetor has one main function, to regulate engine speed. It accomplishes this by metering the amount of air and fuel as required, to sustain combustion per the input of the throttle servo. Thus for a low-speed idle you would have a small amount of air and fuel entering the engine. This would in effect lower the chemical energy entering the combustion chamber and thus lessen engine power and subsequently lower the RPM. As we open the throttle the carb will allow more air and fuel into the combustion chamber, thus increasing engine power and RPM's (revolutions per minute). Now that we know what the carb. has to do lets explore the underlining fluid mechanic properties that allow the carb to function effectively at different throttle settings.
What allows the carb to pull fuel from the fuel tank is the venturi-effect. This states that in a converging funnel the entering fluid velocity increases as it passes through a reduction in the funnels throat diameter. This increase in fluid velocity decreases the localized pressure at the venturi throat to below atmospheric pressure. This low pressure region is precisely where fuel enters the carburetor throat. This is what allows the engine to "suck" fuel from the gas tank. The truth is that the venturi-effect is all that is needed for the engine to get fuel. Pressurizing the fuel tank is really only done to decrease the effects of fuel level on the mixture setting of the carburetor.
Fuel Metering Devices
The venturi-effect draws fuel from the tank but does little to regulate it's flow. It's true that as the engine accelerates the amount of air that moves through the engine increases. The increase in air velocity also increases fuel flow into the induction port, this helps the engine self regulate the fuel up to a certain point.
This is not the only means for the carburetor to meter air and fuel. Engines need a metering device to help regulate the amount of fuel that enters the carburetor. This is accomplished with an adjustable orifice, typically we call them needles or jets. Most engines have a second adjustable needle that helps regulate fuel at low throttle settings. By adjusting these two needles we can control the transition from low to high speed operation of the engine.
How do we adjust a carburetor?
The carburetor is typically adjusted with a long flat-head screw-driver. Carb adjustments are then done by rotating the needled in, our out of the needle seat. The idle speed is adjusted by a screw at the base of the carburetor. This allows the throttle barrel to only close to a preset position.
The carb has three main adjustments that allow you to set the following:
1. Set the idle speed.
2. Set the mixture at idle (Adjustable on 2-needle carbs only).
3. Set the high speed needle mixture and control engine temp
How to make carburetion adjustments:
The throttle stop screw or idle-speed screw (same thing) determines how far the carb barrel will be able to close when the servo is in the neutral position. Typically you set the servo/throttle linkage so that the carb will go from fully open when the trigger is fully pressed to fully closed when the trigger is in neutral. Then you would adjust the idle-stop/speed screw so that there is a 1-2 mm gap when the servo is in the neutral position. You might need to readjust the spring collars on the throttle linkage to force the throttle arm against the idle speed screw.
Tip#1: If you completely mess up the carb setting and you want to go back to the factory recommended needle setting then you must have the carb fully (Yes I mean fully closed) before you can set the low-speed needle to whatever turns the engine manufacturer suggests. Before you close the carb fully back the low-speed needle a bit to make sure you wont put un-needed stress on the needle seat.
Tip#2: There should be no speed change whatsoever when the car is in idle and when you hit the brakes. If the engine's RPM drop either your linkage isn't set right or the idle-speed screw is set too loose. Tighten clockwise until the carb barrel doesn't move when you go from neutral to full brakes.
Tip#3: Some RTR kits have servo horns that are too small. There is not enough servo throw to open the carb barrel, if you use servo trim to be able to open the carb fully, then when you go to neutral the carb doesn't close enough. To compensate for this the novice engine tuner opens up the low speed needle to drop the engine RPM so the car will stay still when at idle... The drawbacks of correcting the linkage problem with the mixture control is that now the low-speed is too rich and the car won't idle for more than a couple of seconds before the engine sputters and dies.
To fix this problem you need to get an after market servo horn that is larger yet still fits your particular servo brand. Now you can go from fully open to fully closed, without using trim. Now you wont have to compromise the carb settings because of lack of servo throw.
At this point you would start the engine warm it up and commence tuning. Adjust the low-speed needle clock-wise until the engine doesn't sputter when at idle. You want a fast idle, if the car wants to move forward a lot, then turn the idle-speed screw counter clock wise to lower RPM until the engine just barely want to engage the clutch. It may take a little time to get the settings right.
Remember you want the fastest idle you can get away with. It will make the engine more stall proof. Some engine will overheat if the idle isn't rich enough, you need to experiment to determine what's the right setting for your particular engine. When every thing is set right the engine will be able to idle through an entire tank without missing a beat.
The high speed needle will control fuel flow into the carb from 1/2 to full throttle. Typically the high speed needle is set to allow the engine to reach it's peak power point, then you open the needle slightly and go racing. On very hot and humid days you will probably have to make a compromise in the tuning department. For most this will mean you will richen up the high-speed needle to lower engine temperatures to acceptable levels. Everyone has their own interpretation of what an acceptable engine temperature is, for me anything under 260 is acceptable. Going higher will typically mean shorter engine life-span and less reliability.
Step 5: Glow Engine Tuning Basics
The first and foremost consideration when attempting to tune your glow engine is understanding the basic parts and their functions. By understanding the fundamentals, you can better tune your engine for maximum performance while at the same time, expanding the life of your engine.
The carburetor is the mechanism that mixes fuel and air in very specific proportions and passes it on to the engine through the vacuum intake. The natural operation of the engines causes of flow of gases to pass through the engine (through the carburetor) and out the exhaust manifold and on to the pipe or muffler. The exact mechanism for this is unimportant for the scope of this tutorial, however it is important to realize that air and fuel pass into the engine by this vacuum method. Depending on how you adjust your carburetor, you can either adjust how much of this gas/air mixture reaches the engine and to what proportion of gas to air passes on to the engine. By reducing the amount of fuel per volume of air, you are making the mixture "lean" and by increasing the amount of fuel, you are making the mixture "rich".
The two types of carburetors are slide and barrel. The old-style barrel carburetors still dominate the market because of their simplicity in design and because of the tendency for designers to hang on to legacy design. These have been around since the beginning of glow-fuel planes. They control gas/air flow by rotating a barrel with a hole cut in either side that allows varying amounts of gas/air mixture to flow through the carburetor as the hole opening enlarges to the venturi (air shaft down the center of the carb body).
This is the most basic and easy to understand part of tuning your carburetor. This spring-tensioned screw limits the closure of the barrel aperture. Although this doesn't affect the mixture of the fuel it does affect the idle speed. The more closed the aperture is, the slower the idle, the larger the aperture, the faster. As you close this aperture up and the idle speed decreases, you will eventually (sooner than later) stall the engine out. In order for the engine to run, it must have enough inertial energy built up in the engine and flywheel to carry it through the entire ignition cycle. Generally speaking, you want to adjust this down to the slowest idle, just before it begins to stall.
Low-End Mixture Adjustment
This adjusts the fuel mixture at or near idle. Some engines lack this low-end mixture valve for reasons of simplicity, however this makes accurate tuning difficult.
For barrel carbs, this mixture valve is generally found where the throttle-arm pivots. Some are countersunk, others are clearly visible from the outside. On slide carbs, they are generally found on the opposite side of the carb from the throttle slide shaft (has an accordion billow type rubber boot over it) next to, but below the fuel-inlet and high-end mixture valve.
High-End Mixture Adjustment
Also known as the Main Needle adjustment, this is the primary fuel mixture adjustment. This is generally found on the top end of the engine, typically next to where the fuel line goes into the engine. Some are flat-head screws like the low-end mixture, others are hand adjustable valves.
It's important to understand that there is a reputation for glow-engines to be difficult to tune. This is a common error in thinking. With a little bit of know-how, tuning a glow engine can really be a simple, pain-free process. People that don't properly understand the basics can easily become frustrated by what should be a simple, straightforward process. Here's how you do it:
Dialing it In
For the purpose of this tutorial we are going to make some basic assumptions. First, we're going to assume that the rest of your car or truck is properly functioning and that you have everything ready to go. Second, we're going to assume that you are able to start your engine and that it at least runs for a second or so.
The first place to start with dialing in your engine is to make sure that you have your idle-speed properly adjusted. Your engine manual should give you specific instructions on setting the aperture gap to the minimum size. It's important that we get this resolved before continuing on. If your engine can't get enough air/gas flow then it won't start/run. A clockwise rotation opens the aperture and increases the idle RPMs, a counterclockwise slows it down.
Second, you should tune the low-end mixture valve. This is done before the high-end (main needle) adjustment because an improperly adjusted low-end can affect the high-end performance. Like most mixture valves, clockwise rotation will "lean" the mixture and a counterclockwise will "richen" the mixture.
To determine whether the low-end mixture requires tuning, allow the engine to warm up completely, and then allow it to idle, uninterrupted for one full minute. If the engine continues to run after the minute is up then your low-end mixture is correct and you're ready for the high-end adjustment. If it dies on you then there are two possibilities; either you are running too rich or too lean. To determine which is the case you must listen for how the engine dies in its idle test.
If the engine's RPM's rev up at the last second and then the engine dies than you are running too lean. To correct this, turn the low-end mixture screw counterclockwise (out) 1/8 of a turn (always make adjustments in 1/8 turn) and retry the idle test.
If, on the other hand, it begins to wind down and you notice a change in how the exhaust sounds in the last few seconds, then your engine is running too rich. To correct this, turn the low-end mixture screw clockwise (in) 1/8 of a turn and then retry the idle test.
Once you have passed the idle test and are able to idle for one full minute (after first warming the engine up, of course) you are ready to continue on. You may have to repeat the above process a few times until it is properly set. Remember, only adjust the screw 1/8 of a turn. It's far too easy to go too far with the adjustment. Setting changes don't always take effect immediately. You may have to run your engine for a few minutes for the full effect to take place.
Now that you have dialed in your low end, any carb mixture problems can be isolated to the high-end (main) mixture adjustment.
Acceleration is the tell-tale sign of how to tune your high end. If you hit the throttle and it takes off suddenly but then suddenly dies or loses power then you have your main mixture set too lean. Try backing (counterclockwise) the main mixture needle out 1/8 of a turn and retry. If it bogs immediately when you hit the throttle (sounds like it's choking), then it's most likely running too rich. Try leaning the mixture out by screwing the main mixture valve in (clockwise) 1/8 of a turn.
The more accurate way of really dialing in the top-end is to take the engine's temperature. A properly tuned engine should run between 210� and 220� Fahrenheit. This can only really be ascertained by using and infra-red thermometer such as the type used by automotive mechanics. On-board or direct-transfer types that measure the heat from the head are inaccurate because, assuming the head is properly dissipating heat, it would reflect a lower than accurate temperature as a majority of the heat energy would be dissipated from the exposed surface of the head. By "looking" at the temperature near the core (actually, area immediately surrounding the glow plug) the temperature can be more accurately read.
The cheap but easy alternative would be to drop a bead of water down the head on the glow-plug and see whether it boils off. If it slowly simmers than it probably is running right around 212�. If it boils to quickly then it's probably too lean and needs to be richened. If it just sits there and doesn't boil at all, then its running too rich and needs to be leaned out.
An engine that is running too lean will run hotter and exceed the 220� degree limit. This can significantly reduce the life of your engine. Although it may be tempting to run your engine as lean as possible (does give a short-lived performance boost), this should only be done if you are very wealthy and like swapping engines out every race. There is no quicker way to kill and engine, honest. This is simply because as you lean the engine out, it gets less fuel to the engine, and more importantly, less lubricant. Since glow fuel is the only means of lubrication for your engine, the lack of it means certain death to your powerplant.
A few final do's and don'ts...
- Give your adjustments time to take affect. Remember that most adjustments won't be immediately noticeable. You need to drive your engine through it's full range for at least a minute. Make sure you make adjustments in 1/8 turn adjustments only!
- Always run on the rich side. It's far better to take a slight performance hit than to turn your engine into a paper weight. Running too lean may give you a temporary thrill, but it's short lived. Your engine must get the proper amount of lubrication at all times.
- Changes in temperature affect your tuning! Whenever the outside temperature changes you will most likely need to re-adjust your engine. Warmer temperatures require a leaner setting where colder temperatures require a richer setting.
Step 6: Engine Maintenance.
There are three basic steps one should take on a day-to-day basis to ensure you continue getting the most from your engine:
1. Keep your engine clean on both the inside and outside. By keeping pariticles of dirt out of the workings of your engine, the operating surfaces will remain smooth and therefore less wear and better performance will result. Always use a fuel filter between your tank and the engine to catch any particles in the fuel. When operating in dusty conditions, use an air filter on your carb to keep particles out of your air intake. When done for the day, use a motor spray to clean off the dirt from the outside of the engine, especially the carb and linkages.
2. Use an after run at the end of the day. Since fuel contains elements that are hydroscopic (they abosrb water), any fuel left in an engine will attract moisture and therefore contribute to rust. It is important that you run the engine dry after your last flight or run to remove the last of the raw fuel. This can be done by simply pulling the fuel line from the engine and letting the engine run out. Apply several drops of after run oil into your carb and turn the engine over to ensure the oil gets distributed throughout the inner workings, coating the metal and protecting it from rust.
3. Ensure all of your nuts and bolts are tight. Between flying or running sessions, check that all of your bolts, such as the head bolts, backplate bolts, muffler bolts, engine mounting bolts, and carb mounting screws, are tight. Also, check that prop nut to ensure you won't be launching a spinning prop on your next flight. An over revved engine, particularly a four stroke, can cause damage without the load of a prop or flywheel.
End of Season Maintenance
When the flying season is over, a small amount of engine care can ensure a successful beginning to the following season.
Clean Engine with Motor SprayRemove your engine from the model and give it a visual checkessentially perform the same checks you would do at the end of a day. Make sure that all bolts are in place and tight. It is not necessary to disassemble the engine unless you feel that there is internal damage or that the bearings require replacing. Replace any stripped bolts or rough running bearings. Clean the entire engine with motor spray to remove all dirt. Finally, load up the engine with after run oil, turning it over to ensure that all moving internal parts are covered. This will go a long way to reducing the chance of your engine rusting in the off season. Store the engine in a baggie to keep the dirt out and the oil in!
Beginning of the Season
The first thing to do before re-installing your engine is to replace the plumbing in your model. Remove the fuel tank and take out the rubber stopper and all brass and silicone tubing. There are components in the fuel that break down brass over time and if left, the tubing will eventually crumble or at the least allow air to enter the line. Clean the residue from the tank itself with a bit of isopropyl alcohol and then install a new rubber stopper assembly with new brass and silicone tubing. Reinstall your tank.
Take your engine from its baggie and use spray motor cleaner to get the after run off the outside of the casing. Re-install your engine to the model. When you are ready to run your engine, remove the glow plug and flush fresh fuel through the engine, turning it over with your thumb over the carb. This will clear out the storage oil. Replace the plug and start your engine as normal.
Step 7: Works Cited