What's This "Nitro" Thing?

"Nitro" in the context of RC means nitromethane (not nitrous oxide!). Nitro fuel is actually mostly methanol (methyl alcohol) mixed with usually about 1/5th nitromethane and 1/5th lubricating oil. RC nitro engines are two-stroke internal combustion piston engines similar to those that power dirt bikes and weed wackers. They burn fuel and produce exhaust, creating power on every second revolution. RC engines, however, do not use spark plugs, but instead have glow plugs like diesel engines -- there's no spark involved, there's just a wire fillament that stays red-hot to ignite the fuel-air mixture. They are sometimes mistakenly called "gas" engines. They are not, however, and can not be powered by gasoline.

Fuel & air is mixed in a carburetor that generally has between one and three adjustment screws for idle speed and fuel-air mixture tuning. Spent exhaust travels through a header and into a "tuned pipe" that looks & acts as a muffler and also sends pulses of pressure back to the engine to help its internal plumbing work properly.

To start a nitro engine, you have to preheat the glow plug by attaching a hand-held probe called a glow igniter to an exposed plug on the top of the glow plug, which is an inch or so down a hole in the center of the head heat sink. Then you have to physically start the engine turning. On dirt bikes, there's a kick start for this. With the Nitro XRC vehicles and some hobby-level nitro RCs, there's a hand-held starter unit that looks and works like a cordless drill. You insert the end, push a button and wait for the engine to fire up. On some other hobby-level RCs, there's a pull starter like you'll find on lawnmowers and weed wackers.

Because they work off of internal combustion, nitro engines they make a lot of noise, more noise the faster you go. They expel exhaust gasses that are somewhat noxious and can cause eye irritation and coughing. The exhaust also contains some oil in aerosol form, and this can soil things it comes in contact with. Nitro vehicles should always be started and run outdoors. Because of the very loud noise, care should be taken to respect other people, and you should not run them in quiet, peaceful parks or residential areas and you should never run them during hours that people rest or sleep.

Here are more pages with straightforward info about nitro RCs:

• Nitro or Electric? - Differences, pros & cons
• Nitro RC components - power systems
• Nitro RC components - other