Monday, December 28, 2099

How a nitro engine works

You may be interested in purchasing a nitro R/C car, but you may want to know how it works first. This post will explain how.

First off, with the purchase of a nitro R/C car, you will receive a 2.4GHz transmitter. It comes in the "pistol-style" format, with a throttle/brake lever, a steering control, and some other small dials that aren't important right now. The transmitters usually take 4 or 8 AA batteries. Once you get that hooked up, it will send a signal to the receiver on the car itself. The receivers usually take 4 AA batteries, and it tells the car what to do based on what you do with the transmitter.

Typical R/C transmitter

Once the receiver gets the signal from the transmitter, there are 2 basic motions that are controlled: steering and throttle/brakes. The steering is controlled by a servo, and the throttle/brakes are controlled by another servo. When you turn the steering wheel on the transmitter, it tells the servo on the car to turn which turns the wheels. Unlike a "toy-grade" car, it is not a 3 position system (100% left, center, or 100% right", but it can turn at any angle in between, based on how far you turn the wheel on the transmitter. Just like a real car.

Steering servo

Now for the throttle/brakes, it is somewhat similar. When you pull the throttle lever on the transmitter, its signals the throttle servo to turn, which opens up the throttle. When you push the lever out, it engages the brakes. Most cars (at least off-road) have 4 disc brakes, which do a VERY good job of stopping the vehicle, even at high speeds, in just a foot or two, depending on the surface type.

Throttle/brake servo

Now for how the engine runs. You start out by putting some Nitromethane into the fuel tank, and priming the engine (I will go into detail of the starting process later on). Next you put the "glow plug igniter" onto the glow plug, and pull on the pull starter. A "glow plug" is just like a spark plug in a car, but instead of sparking every time, it is heated up once with the igniter to get the engine going, and compression keeps it running after that. Anyways, once the engine is running, you can control it with the  transmitter. When you apply the throttle, it opens up the carburetor, which is a device that mixes the air and fuel together. The wider the carb is opened, the more fuel and air that can get in, which makes the engine run faster, making the car go faster. When the brakes are applied, the carb is closed almost all the way, and the brakes are then engaged, slowing the car down.

Fuel tank
Nice little diagram of the nitro engine setup

The engine is hooked up to the crankshaft, which rotates all 4 tires when the throttle is applied. The tires have very high-torque for the car's small size, which makes them go very fast, with really snappy acceleration. The carburetor has some adjustments that have to be adjusted. They are called the "high, low, and idle speed needles". I will go into further details about them later, but the high speed adjusts the air/fuel ratio at high RPMs, the low speed adjusts the ratio at low RPMs, and the idle needle adjusts the engine speed while it is at idle.