Car Tuning,Car Finance,Auto Loans

Posts Tagged ‘Rc Cars’

A Few Considerations

When choosing an RC car there are a few considerations you need to take into account first. Do you have open land or a large parking lot that is flat where an RC car can be driven? RC cars can quickly get destroyed if you race over uneven land – one bump and you may be out a hefty price! If you live in the city are there any rules restricting these vehicles or neighbors that may complain about the noise gas powered RC cars make? If so you may need a muffler on your exhaust or a lower-powered engine.

Picking A Kit Or RTR RC Car

Gas powered RC cars run on a nitro methane fuel that you can refill for unlimited running time and 80+ mph isn’t out of the question! These cars or trucks are typically powered by a small two-stroke engine burning nitro methane, giving them the moniker of a NITRO car or truck. Different engines burn different mixtures of fuel, however, so that’s something you want to watch for when purchasing your car. Speaking of purchasing your RC vehicle there are two big questions you need to ask yourself. Do I want to build the car myself or do I want to purchase a RTR or “ready to run” vehicle? The DIY kits are a lot more expensive and unless you know what your doing then a RTR RC car is probably more inline with what your looking for.

The Little Engine That Could

Can gas powered RC cars really go 80+MPH? Yes! Most nitro methane burning cars have what is called a two-stroke “glow” engine. The two-stroke engine is equivalent to a weed-eater motor which can pump out up to 5HP which is a LOT considering the size of an RC car. The “glow” refers to how the engine gets its spark to ignite the fuel. A “glow starter” heats up a “glow plug” which in turn causes the fuel to ignite and WHAM, you get your breakneck speeds.

Not All Fuels Are The Same!

The next thing that you have to worry about is what kind of fuel mixture you are going to be using in your car. The type of engine that you choose will dictate what kind of mixture the manufacturer will recommend. Typically in gas powered RC cars the mixture is between 10-40%. Once you have your car up and running you can experiment with different mixtures in your engine to get the kind of performance that compliments how you race your car.

When I first started racing Gas Powered RC cars, I used to struggle to get the engine into tune, while I was able to get the engine to start on a dime and it used to run fine for almost an entire fuel tank, it always seemed to over-heat near the end of the run. After many hours out on the track I can now finally say that I’ve got it down, tuning for me is now a 5 minute operation before I take my RC car out, and once it’s dialed in I only need to adjust one needle a fraction of a turn to get it back to it’s optimal settings.

I assume that your understand the basics of a RC Nitro Engine and how it works, if not please see my other articles which you can find on my website, see the resource box for details.

The Idle Screw
I always start with the idle screw, I adjust it so that the car will idle high when I’m first dialing in the engine. Once I get the engine up to temperature and with a tube that can keep it running without stalling I slowly adjust the idle down to the point where it’s about to stall, then I turn it back about 1/4 to 1/2 turn depending on the temperature. If your car stalls often it can be worth while increasing the idle to prevent this, it’s only a temporary fix while you sort out the other tuning issue, but it helps keep frustration levels down.

Low Speed Needle.
One of the great debates is which needle to adjust first, if your carburetor only has one needle adjustment screw then it’s not a problem, but if like most glow engines you have two you need to decide which to tune first. I always start with the low speed needle, this is because when you adjust the low speed needle you change the high speed needle. Once the low speed needle is dialed in you shouldn’t have to adjust it again. Make sure you keep it slightly on the rich side, when you RC Car idles the combustion chamber should start to fill up with fuel, this helps keep it cool. After a while the engine will stall, by measuring this you can tell if it should be richer or leaner. A good time is about 30 – 60 seconds before it stalls. The RC Car should pull off quickly from a standing start and should not bog down or flame out when you apply full throttle.

High Speed Needle.
Once you have your low speed adjustment needle dialed in it’s time to start getting the power out of the RC engine. This is done with the high speed needle, which adjusts the air to fuel mixture of the engine while it as high RPM (about 40% and up). Keep an eye on the trail of smoke as this is your first clue about the tune. You want to have a lot of smoke coming out of the engine at all RPM, if at some point there is little or no smoke then you are running too lean.

Hints, Tips and Tricks
Turn the needle clockwise to lean out and counter-clockwise to richen the mixture. A lot of smoke means you tune is rich. The sound can tell you about your tune. Reading your glow plug after a run will tell you a lot about your tune. Make sure to run your engine on the rich side, this will extend it’s life. A lean engine will always put out more power, but it will shorten the life of your engine. Temperature, air pressure and humidity play if big part in the tune, different days will need different settings.

For your RC cars suspension to absorb large impact or bumps, we must use a ”thicker” or more viscous oil. The more viscous the oil, the more denser it is. This helps to decrease the rate of body roll.

When tuning large RC cars such as the buggy or truck, one is to note that any impact sustained is to be absorbed by the chassis (framework) and not the suspension.

The thinner your shock fuel,the faster the body roll of your car. Hence it will have more grip on the road and a higher “turn in”.

There are two ways of increasing the grip of your vehicle. Firstly, you can soften the suspension at that particular end. This can be achieved by decreasing the tension of the spring, using a less viscous oil or using a shock piston with more holes. The last two steps allows oil to reach the carburetor and get burnt more quickly. Alternatively, you can change the position of the shock shaft relative to the chassis. If the shock absorber is mounted at the end of the arm, the tyre will experience a force equivalent to that of the entire spring.

Another thing to note is that when the shock is placed closed to the chassis, the car will have more suspension travel. This is because of the force exerted primarily by the spring.

There are also more complicated factors such as adjusting the angle of the shock to influence the resistance being applied to the arm. If the shock is in a more ‘layed down’ position, the shock will definitely be softer.

These are just some of the factors to consider when adjusting your suspension to suit the needs of your “over-sized” RC truck or buggies. Enjoy yourself and have fun!