Has any invention -- OK, short of the wheel -- changed human history quite so much as the engine? Consider its history: After millennia of using strong animals like horses and oxen to pull vehicles, or to power other forms of machinery, humans began dreaming of machines that would power themselves. They didn't, though, agree on what kind of fuel might power the earliest engines. One early effort used hydrogen (an idea we've come back to as fossil fuels lose their appeal). The first winner, however, was steam -- with coal being the raw fuel that boiled the water. Later, it was mainly a German, Karl Benz (his last name might be familiar) who was responsible for the ultimate choice of petroleum fuel (that's gasoline, to us everyday people) to power what became known as the internal combustion engine. "Internal combustion" means that the vehicle or machine has no external power source -- it's essentially a little power plant all its own.
Today, the internal combustion engine fuels not just cars but airplanes that take humans around the world in a matter of hours, the rockets that have sent us to space, and a variety of essential machines. Are you ready to find out how much you know about this vital invention? Our quiz is mostly on automobile engines, but not entirely -- we've slipped in a few questions about aviation and spacecraft engines. Test your knowledge now!
Though the name "engine block" makes it sound kind of inert, don't be fooled. This is where the real work happens.
The pistons in most engines have a four-stroke action. This means they go down twice and up twice. We'd go into more details, but we don't want to give away the answer to future questions!
The pistons move up and down in the cylinders. This is where compression and ignition take place.
"Ablution" means washing or bathing. The four parts of a four-stroke cycle are intake, compression, ignition (the one we left out) and exhaust.
Most directly, the pistons move the connecting piston rods, which move the crankshaft. The movement of the camshaft is synchronized to the movement of the crankshaft. So, like they say on Facebook, it's complicated. But if we had to name a key player here, it's the crankshaft, which carries power to the wheels.
While "fuse box" might have looked tempting, the fuses control the other electrical items in your car -- the fuel pump, for example, or the radio. It's the spark plugs that directly create the spark (hence the name) that ignites the fuel-air mixture in the cylinders.
An engine seizes when it overheats, and small parts fuse together. This sounds like a lack-of-water problem, but it actually overheats because of a lack of lubricating oil.
Engine oil is graded by its thickness, or "weight," which is a measure of its ability to lubricate under varied conditions, from cold weather to hot, for example. So an oil marked 10W-40 is also called "40 weight."
Most people know the main purpose of engine oil, which is lubricating the engine. However, it also keeps the temperature low (because friction, which it prevents, generates heat), and cleans the engine. This last part is why you need to change your oil regularly: It knocks loose and carries away crud on the engine parts, but these can build up in the oil in the crankcase.
There are cars on the road today which still have carburetors, but fuel injection is considered superior. Both are methods of mixing a fine spray of fuel with air, to be ignited in the cylinder.
OK, there were some high-performance cars that had fuel injection prior to the '80s. But that decade was when fuel injection went mainstream.
Back in the Rodney Dangerfield era, a lot of self-effacing comics used this expression for comic effect. "My wife's like the engine on my old Chevy -- on a cold morning when I need her most, she won't turn over!" (Rimshot).
When you hear your engine "cranking" but it won't start, what you're hearing is the sound of the starter motor trying to spin the crankshaft a few times. When it can't do that sufficiently to get combustion started, the car overall won't start.
A turbocharger shunts some of the cylinders' exhaust gases back into them, creating more compression on the next downstroke. And, as you learned in physics, that greater compression will create an "equal and opposite reaction" -- a more powerful exhaust stroke. Clever!
You'll hear this part referred to either as the timing "belt" or "chain." Either way, it keeps the pistons and valves in sync, or, more broadly, the crankshaft and camshaft in sync.
If you remember physics class, "torque" is rotational power or twisting force. In engines, the rotation is that of the crankshaft.
This is the last thing you want to do on a hot day when in traffic -- which is a common situation in which the engine might overheat! But it actually does help, by drawing heat away from the engine and into the passenger compartment. Which is actually what the heating system is designed to do, just not primarily as an emergency-overheating measure.
If "ring job" doesn't sound like fun to you, it also doesn't to the mechanics who had to perform them. This hard, time-consuming task was once the bane of mechanics, but nowadays, it's rarely necessary.
Diesel engines do cause fuel to combust. However, they do so strictly through compression of the fuel-air mixture, with no spark plugs. This requires a special kind of fuel.
They're named for Rudolph Diesel. Yes, it really is a last name -- but don't let actor Vin Diesel off the hook; his given name is Mark Sinclair!
If the fuse that supplies electricity to the fuel pump blows, the pump will die. If the timing belt breaks, the crankshaft and camshaft won't turn. Either way, it's game over, right there in the street. Engine knocking, on the other hand, you can put up with for quite some time.
Green has long been a common color for coolant, but really, it can be any color. The dye is added to a colorless base, to differentiate it, and yellow and pink are among the possible choices. Really, why does going to Pep Boys have to be as hard these days as going to Sherwin-Williams?
Surprised? Even fuel can be used as a coolant, and this is often done in airplane engines. It helps that at altitude, the air outside the fuel tanks is quite cold, so the chilled fuel can cool down the hot engine oil, while the engine oil heats up the fuel for use in its main capacity -- to power the plane.
Motorcycles often have air-cooled engines; it's easier to use air cooling on smaller engines that larger ones. However, they're also noisy -- another reason is they're not popular for passenger cars.
This name is fairly self-explanatory. A belt that powers multiple accessories wends its way up and down and all over the engine.
Occasionally, they might mean a turbocharger, but usually this refers to a supercharger. The difference is, a supercharger doesn't just recycle exhaust gases, but uses the engine's powertrain to force air into the cylinders.
As mentioned in a previous question, supercharging draws on the energy generated by the power train to push air into the cylinders. For this reason, it's not as efficient as simply recycling exhaust. So why do people like it? It eliminates "turbo lag," the short delay between when you call on the car for more speed and when the turbo kicks in.
We're used to hearing the word "throttle" in terms of planes and motorcycles -- it's what feeds gas to the combustion system. But cars and trucks have them, too. We just call the foot throttle a "gas pedal."
The "redline" is literally where the measurements on a tachometer go from black into a red zone, and for most cars this is somewhere around 6,000 RPM. In contrast, Formula One cars redline nearer 15,000 RPM.
It's an outdated measure today, but early on, it was of obvious interest to makers and users of engines, how those engines compared to a draft horse. Horsepower is measured in watts.
It's hard to imagine steam generating so much force that it moves pistons and powers a vehicle the same way fuel-air combustion does. But it's true: steam was sufficient to power trains, back in the day!
Jet engines are also internal combustion engines. But they differ from automotive engines in that their main purpose is to create thrust, which they do via a "jet" of hot gases exiting the rear of the aircraft.
We should explain that you can drag race in any kind of car -- hence the informal competitions you might see on back road. But modern dragsters are "rocket cars," using jet engines.
In a steam engine, the combustion takes place away from the chamber where the fluid moves the pistons. In simpler terms, combustion heats the water, but elsewhere, steam moves the pistons.
America's space shuttles used Rocketdyne engines that burned cryogenic fuels. This trend will likely continue with rocket launches in the near future.