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.

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What you need to get started

So if you have read this far and still are interested, I will explain what you will need to get and do to get started in this hobby. Everything that you need are as follows:

-Actual nitro R/C car (you can order them online, but if you live near a hobby shop, I recommend going to that first)

-Nitro "starter kit" (contains basic tools and things you have to have for the car)

-Nitromethane fuel (same thing, easily bought online or in hobby shop)

-After run oil (used in the engine after its been run to keep it lubricated and running strong)

-Spare glow plugs (in case the one you have burns out, it needs to be replaced)

-AA batteries (usually 8 or 12)


The actual nitro car usually comes with: the car, transmitter, 1 glow plug, and a manual and sometimes some other small miscellaneous parts such as stickers. (usually $120-$300+)

The starter kit usually comes with: 2 cross wrenches that fit every bolt and nut, as well at the glow plug on the car, the glow plug igniter, a charger for the igniter, a fuel bottle to get the fuel into the tank, and 2 screwdrivers, one flat-head and one phillips head. (usually $15-$25)

The nitro fuel has a whole bunch of different prices, based on where you get it from and how much you get. Online, I paid $35 for a gallon (I will include links), but if you get a quart, it can be about $25 so i recommend buying in gallons so you get the best deal. I'm not sure how much hobby shops charge, but I imagine it will be cheaper online.

After run oil is cheap, I got a 2oz bottle for like $5 off eBay.

Spare glow plugs are also cheap, I got one for about $6 off eBay.




Okay now for some recommended sites....

To get the car, I really recommend NitroRCX. They have a pretty decent array of nitro, as well as electric cars. They also sell R/C boats. But what really makes them stand out to me is how they have the best prices around. I got the 1/10 scale Exceed RC Hyperspeed buggy, it cost $120, which is very cheap for a nitro car. Despite the cheap prices, this car is very durable and very fast. NitroRCX also has free shipping, if you put the coupon code "rcxfreeship" into the box. (the code may not work forever, but it works as of right now)


For the starter kit, if you buy from NitroRCX, it will automatically include one with your purchase for $15. This is the best price I have found for a starter kit.
 

 

starter kit

I got my nitro fuel from Torco Nitro, as they have good prices, and free shipping. Nitro comes in %, determining how much oil is in the mixture. For the buggy I got, it uses 20%. Street racing cars use a lower number I think, but the website you get from will tell you which to use.
 

 

20% nitromethane from torco

After run oil is pretty much all the same. Glow plugs come in different heat ratings, Hot, med, and cold. For an off road buggy, use a Med or preferably a hot one. For on road racing, its usually a cold one that is used.


 

 

This is the after run oil i use.

 

 

Here is a glow plug. The copper washer is important.

 

 

 

 

 

 

 

 

Thats basically all you need to get started. I bought everything i needed for about $180. Which is actually a good price for all I got.

Starting your nitro car for the first time

Okay, now if you are interested enough to buy one of these, I will explain what you need to do when you first get the car. The first thing you need to do is open up the starter kit, and charge up the glow plug igniter. You need to charge it for at least 8 hours or so the first time. Without it, you will not be able to even start the car. Once that is on charge, take out the glow plug from the engine and add 2-3 drops of after run oil into the piston. Pull on the pull starter cord a few times to get the oil all over the engine. This puts an initial film of lubrication into the engine so it will not wear out quickly when you go to start it. Replace the glow plug now. The next thing you have to do is go over the entire car and tighten any screws that happen to be loose. Not too tight, just snug. Only tighten the screws that hold stuff together, not the needle adjustment screws on the carb.

Next you can put batteries into the transmitter and receiver. There will most likely be a door you have to unscrew on the car to get to the battery pack. Once the batteries are in, first turn on the transmitter, then the receiver. If you ever turn on the receiver on the car first, it won't have a signal from the transmitter to follow, and may go out of control. The two units should already be synced from the factory, but if they are not, there will be instructions on how to sync them. Usually you just have to press a button.

The next thing you can do is program the failsafe, if there is one. I know the buggy I ordered has it, but I'm not sure about any other ones. If it has a failsafe, start by pressing the "F/S set" button on the receiver, while doing nothing with the transmitter. Now, while the LED is flashing, engage the brakes all the way with the remote. Then push the button again. What this does is if the car goes out of range, or if the battery power drops too low, it will automatically put the brakes on so your car doesn't go flying down the street and smash into anything in its way.

 

 

2.4 GHz receiver with failsafe

Once the glow igniter is all charged up, you are ready to start your car for the first time. Begin by going outside, and pouring some fuel into the starter kit's fuel bottle. Fill up the fuel tank with nitro, and make sure all fuel lines are connected to their ports. Now you have to prime the engine. This is simple, just put your finger over the exhaust port and pull the chord a few times until you see the fuel go through the line and into the carb. Once the fuel reaches the carb, stop or you will flood the engine. You also need to oil the air filter. Simply pull the whole thing off the car, and pull the foam pieces out of their rubber housing.     
Then take some basic vegetable oil found in your kitchen, and put a few drops on the foams and rub it in to spread it around. Don't make it dripping wet, but make sure it is oily. The oil particles trap dirt and dust from reaching the engine, which will break it if they enter.

Now that it is primed, its ready to run. Clip the igniter onto the glow plug and pull on the cord. Make sure you do short, quick pulls, as the chord isn't very long. The first time you start it, chances are it will not stay running. I will explain how to tune it to run in the next post. Also, for the first 3-5 tanks of fuel, you can not run it like you want to. You have to "break it in", which makes the engine last longer. That will also be explained in the upcoming post(s).Posted