On the first leg of our road trip, we’re exploring the history of engines and how they work, with a little help from Car Talk’s Ray Magliozzi. The fundamentals of the internal combustion engine, haven’t really changed since it was first invented in the 1800s. How do tiny explosions power our cars? And how did gas-powered cars come to dominate over electric and steam-powered engines?

(Subscribe to our newsletter to get downloadable road trip activity sheets!)

The engines used in most cars today are called internal combustion engines, but when they were first invented they were called “exploding engines” by some. That’s because your car is powered by lots of tiny, controlled explosions happening inside its engine.

For most cars, that’s at least 6000 explosions PER MINUTE when you’re driving down the highway. An explosion of explosions!

Here’s how it works: When a fuel like gasoline is mixed with air, and then exposed to a bit of heat — boom! That’s called combustion. This reaction produces exhaust and heat.

Exhaust is mostly made up of gases so when it’s heated up, it expands. This expanding gas exerts a pressure, pushing on the things around it. In this case, the gas pushes on sliding parts of the engine called the pistons, which are metal rods that fit neatly in metal tubes.

When gases push on them, the pistons move up and down inside their tubes, sort of like your legs move up and down when you pedal a bike. The moving pistons, turn the crankshaft, which makes the wheels turn.

by Jake ONeal.

From Visually.

– See more at: https://visual.ly/community/infographic/transportation/how-car-engine-works-animated#sthash.517HYdWy.dpuf

Photos: Early automobiles
Family Outing
Karl Benz (in light suit) on a trip with his family with one of his first cars, which was built in 1893 and powered by a single cylinder, 3 h.p. engine. His friend Theodor von Liebig is in the Viktoria.
Hulton Archive/Getty Images
Electric Landau
14th November 1896: Mr Walter C Busey's electric landau on the London to Brighton motor car run.
Hulton Archive/Getty Images
The Lifu
circa 1899: A steam car named 'The Lifu'.
Hulton Archive/Getty Images
Steam powered vintage Stanley constructed in 1908
Essen, GERMANY: Bill and Rachel Rich from Great Britain drive their steam powered vintage Stanley constructed in 1908, 04 April 2006 on the fair grounds in Essen, western Germany, in preparation of the "Techno-Classica" fair. The show, running from 06 to 09 April, is a forum of the vintage car industry, the classic car dealer network and the classic club scene.
President Theodore Roosevelt's Car
circa 1910: President Theodore Roosevelt in an American Government 30-horsepower White Steam Car.
Hulton Archive/Getty Images
Electric Car
An Anwell Johnson electric car at the Electrical Vehicle Parade in Kingston upon Thames, 19th June 1915.
Topical Press Agency/Getty Images
Model T Ford
20th October 1920: Friends going for a ride in a Model T Ford stop to pick up another passenger.
Three Lions/Getty Images

Audio Transcript

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MOLLY BLOOM: Big questions help us explore our world and connect with each other in New ways. Now's your chance to come together with other Brains On listeners to support the show you love. Make a gift by June 30th to help us reach $5,000 in listener donations and you'll unlock a $5,000 challenge from our generous board of directors. Contribute at brainson.org/donate.

GABRIELLA HOPPER: You're listening to Brains On where we're serious about being curious.


MOLLY BLOOM: Gabriela, we got our snacks?




MOLLY BLOOM: Sunglasses?


MOLLY BLOOM: Podcasts and music to listen to?

GABRIELLA HOPPER: Check. We are ready for a road trip through the world of cars.

MOLLY BLOOM: Gas-powered cars.

GABRIELLA HOPPER: Electric cars.

MOLLY BLOOM: Steam-powered cars.

GABRIELLA HOPPER: Steam-powered cars?

MOLLY BLOOM: Yeah, they actually existed and you will learn all about them. Plus how do engines work and how were cars invented.

GABRIELLA HOPPER: We'll answer those questions. Now, keep listening.

MOLLY BLOOM: You're listening to Brains On! from American Public Media. I'm Molly Bloom. We're hitting the road to answer your questions about cars, riding in cars, designing cars, engines, traffic, and other vehicular topics. My co-host for this series is 10-year-old Gabriella Hopper from Lorton, Virginia. Hi, Gabriella.


MOLLY BLOOM: Gabriella is one of the many, many listeners who have sent us questions about cars. Gabriella, how did you get interested in cars?

GABRIELLA HOPPER: Well, I found a book that had a lot of cars in it. When I opened the book, I saw a lot of cars and they just really got me interested in cars.

MOLLY BLOOM: What is the most fascinating thing to you about cars?

GABRIELLA HOPPER: I like to see the different designs of cars because they're all so different and they come in so many shapes and sizes.

MOLLY BLOOM: After you read that book about cars, how have you kept learning about cars?

GABRIELLA HOPPER: I like to watch racing like race cars on the TV when I get the chance to. I see the different types of race cars that are made and they're just so cool. I like looking at them and seeing how they're made and how they work.

MOLLY BLOOM: Have you done any exploration of how cars work, like the engines, the insides of them?

GABRIELLA HOPPER: I haven't, actually. As much as it seems I have not.

MOLLY BLOOM: Well then, today, this episode is perfect for you because we're going to learn all about it. Cars are ubiquitous. They are everywhere. So it is not surprising that there is so much curiosity surrounding these motorized machines.

GABRIELLA HOPPER: Today, we're starting with these questions.

AARON: Hi, my name is Aaron and I'm from Honey Brick, Pennsylvania. My question is, how does gasoline make cars move?

NANDINI: I'm Nandini Hields. I'm 7-years-old and I'm from Bath, England. My question is, how do gasoline car engines work?

MOLLY BLOOM: Excellent questions and a great place to start. The engines used in most cars today are called internal combustion engines.

GABRIELLA HOPPER: Or exploding engines.

MOLLY BLOOM: That's right. Exploding.

GABRIELLA HOPPER: Exploding engines sound dangerous.

MOLLY BLOOM: Don't worry, they're not too dangerous. Your car is powered by lots of tiny controlled explosions happening inside its engine.

GABRIELLA HOPPER: For most cars, that's at least 6,000 explosions per minute when you're driving down the highway. An explosion of explosions.

MOLLY BLOOM: That's a lot of explosions.

GABRIELLA HOPPER: When a fuel weight gasoline is mixed with air and then exposed to a bit of heat, boom.

MOLLY BLOOM: That's called combustion. This reaction produces exhaust and heat.

GABRIELLA HOPPER: Exhaust is mostly made up of gases. So when it's heated up, it expands.

MOLLY BLOOM: And this expanding gas exerts a pressure, pushing on the things around it. In this case, the gas pushes up on sliding parts of the engine called the pistons. These are metal rods that fit neatly in metal tubes.

GABRIELLA HOPPER: When gases push on them, it makes these pistons move up and down inside their tubes.

MOLLY BLOOM: These parts moving up and down make the wheels go around. Think of it like the way you pedal a bicycle. Your legs go up and down, turning a crank which then turns the wheels. The pistons like your legs move up and down, turning a piece of the engine called a crankshaft.

GABRIELLA HOPPER: When this crankshaft turns, it makes the whole wheel turn.

MOLLY BLOOM: And that makes the car move.

GABRIELLA HOPPER: All thanks to tiny explosions.

MOLLY BLOOM: Explosions led listener Annika Della'O to write in with this logical question. Why doesn't the fuel in our cars make the car burn up? So we enlisted Annika to talk to someone who knows cars. A familiar voice and laugh to Public Radio listeners far and wide.



MOLLY BLOOM: This is, of course, Ray Magliozzi. One of the hosts of the legendary NPR show Car Talk.

RAY MGLIOZZI: Go ahead, Annika. I'm ready.

ANNIKA: Why wouldn't the fuel in the cars blow up the car?

RAY MGLIOZZI: Oh, boy. I was afraid you were going to ask that. Oh, that's a good question. So we're going to put just enough gasoline in, not too little. But more importantly, not too much so that when that explosion takes place and pushes that piston out of the cylinder, it's just enough so that it doesn't break everything. In fact, it's a very good question because we've got to make sure that the cylinder, the larger thing that the piston fits into, that that doesn't go anyplace.

Let's imagine that cylinder is attached to a big hunk of metal, whether it's steel or iron or aluminum, and it's really substantial. When that explosion takes place, the explosion is trying to explode everything. It's trying to blow the bigger can apart, that is the cylinder. It's also trying to push the piston, God knows where, into the neighbor's yard, but we don't want that to happen. So we're going to encase the cylinder in a big chunk of metal, and that thing is called the engine block.

Now, in your car, you have an engine block that has not just one cylinder, it may have four or six or eight or 10. But for the purposes of this explanation, one is good enough. If you understand how one works, we'll understand how 2 and 4, et cetera, et cetera work. This big hunk of metal contains the explosion so that the cylinder doesn't blow apart.

ANNIKA: What happens to the fuel when it gets used up?

RAY MGLIOZZI: Oh, that's a great question. What's left behind is a waste product. We call that exhaust. So the exhaust has to escape and has to make room for a fresh charge of gasoline and air. Every engine has valves at the very top of the cylinder, which allow the exhaust gas to escape and allow a fresh mixture to come in. These valves are called, ready for this?

One of them is called the exhaust valve, duh, and the other one is called the intake valve. Here's what happens. Let's say we have this situation where we have the gasoline in the cylinder, we have the explosion, we push the piston down, the piston comes flying back up again. While it's flying back up, this exhaust valve opens up. And what happens when it opens up is it pushes out the exhaust into the air.

ANNIKA: When you go faster, does it make the engine go faster?

RAY MGLIOZZI: To make it go faster, I'd want a bigger explosion. I'd want to put in more gasoline. Instead of putting in one tiny drop, I might put in a drop and a half or two drops or three drops. The more I put in, the bigger the explosion. The explosion will be, now, there's a limit to how much gasoline you can put in because if you put in too much, it won't burn at all.

But if you put in just the right amount every time you can get the engine to go. When your engine is sitting there, when you stopped at a traffic light, for example, your engine is turning about 500 revolutions per minute. That's why it's so quiet, you can barely hear it. It's just [VOCALIZATIONS]. When you accelerate, when you step on the gas pedal, you are doing two things, you're letting in more air.

And then when we inject the gasoline and depending upon how much gasoline we put in, that determines how big the explosion is and how fast the piston moves downward. So we don't put the gasoline in until the very top. When the piston is all the way up at the top, we put the gasoline in, the explosion takes place. And if we put a little in, it pushes the piston down slowly. If we put a lot in, it pushes the piston down very, very hard, very fast, and that makes the engine run faster and faster and faster. Pretty neat.

ANNIKA: It's amazing. What advice would you give someone who wants to begin working on their own cars?

RAY MGLIOZZI: Well, you should make sure that you practice all the safety things you need to. It's very important to have somebody who's done this stuff before to take you through it step by step. I had my dad and I also had my older brother. So my brother who had a car because he was a lot older than me, as you might imagine in a car that didn't run very well, so every week he was fixing something.

I would sit there and watch him work. And he had learned from my dad. Little by little, I learned to watch him, to observe, to learn how you could hurt yourself and how to avoid hurting yourself, how to avoid breaking parts of the car. And that's the way to learn and it's and it's a tremendous amount of fun. Working on cars is a lot of fun. If you get a chance to do it by watching somebody do it, you can say, gee, can I try that next? If they're unafraid, they'll let you try it and that's how you'll learn.

MOLLY BLOOM: Well, Thank you so much for teaching us about cars today.


RAY MGLIOZZI: Thanks for calling. I'm glad to be on.

MOLLY BLOOM: Many Thanks to Annika Della'O for sending in that question and helping us with that interview. Now, speaking of tiny explosions, Gabriella, are you ready to have your mind blown? It's time for the mystery sound.

GABRIELLA HOPPER: Mystery sound.

MOLLY BLOOM: Here it is. Any guesses?

GABRIELLA HOPPER: It sounds like the rain pouring down when you're driving.

MOLLY BLOOM: Excellent guess. We'll be back with the answer in just a bit.

GABRIELLA HOPPER: Our next verses episode is coming up in July, and we want to know which side you're on.

MOLLY BLOOM: Which do you think is cooler, deep sea or outer space?

GABRIELLA HOPPER: Send your argument to hello@brainson.org.

MOLLY BLOOM: It's your answers, questions and mystery sounds that make this show possible.

GABRIELLA HOPPER: In order to thank all the kids who share their energy and ideas with us, we started the Brains Honor Roll.

MOLLY BLOOM: Listen for the most recent group to be added to this illustrious list at the end of the show.

GABRIELLA HOPPER: If you're looking for some more fun to keep you busy in the car, you should subscribe to our newsletter.

MOLLY BLOOM: If you do, we'll send you some downloadable activity sheets dreamed up by the Brains On team that will help you pass the time in style.

GABRIELLA HOPPER: You're listening to Brains On from American Public Media. I'm Gabriella Hopper.

MOLLY BLOOM: And I'm Molly Bloom. Ready to find out the answer to that mystery sound?


MOLLY BLOOM: Let's hear it one more time. A final guess?

GABRIELLA HOPPER: Now that I think about it, it sounds like an old car's motorized engine heating up.

MOLLY BLOOM: Excellent guess. Here's the answer.

BEN: That was the sound of a car driving past us on the Autobahn. The Autobahn is a highway in Germany that there's no speed limit. We usually drive about 100 miles per hour. I'm Ben.

JACK: And I'm Jack.

BEN: We're from the US.

JACK: But we live in Ethiopia.

BEN: We recorded the soundwave in Germany.

MOLLY BLOOM: You were close. The car was driving and that little vroomy sound was another car driving by. Have you ever driven that fast?

GABRIELLA HOPPER: I don't think so. Well, my granddad, he drives pretty fast in his sports car but I don't think ever that fast.

MOLLY BLOOM: It's pretty fast. The Autobahn really gives those engines a workout. And the amazing thing about the internal combustion engine is that the fundamentals of the way it works have not changed since it was invented and refined in the 1860s and 70s.

GABRIELLA HOPPER: That leads us to our next question.

OLLIE: Hi, my name is Ollie. I'm 9 years old and I live in Austin, Texas. My question is, when was the first car invented?

GABRIELLA HOPPER: Like many great inventions, the car wasn't dreamed up overnight. There were actually quite a few different people trying to come up with a self-powered vehicle that didn't rely on a horse.

MOLLY BLOOM: It was a process of innovation that spanned decades. Etienne Lenoir in France patented an internal combustion engine that used coal gas and air in 1858.

GABRIELLA HOPPER: He demonstrated that it could be used to move boats and a three-wheeled carriage.

MOLLY BLOOM: Called a hippo mobile, which much to my dismay does not look like a hippopotamus.

GABRIELLA HOPPER: But his engines were mostly used for stationary purposes. Meaning, they powered things that didn't move.

MOLLY BLOOM: Like water pumps or printing presses. But tinkerers started playing around with Lenoir design. Nicolaus Otto.

GABRIELLA HOPPER: His name is Otto?

MOLLY BLOOM: Actually, it's a homonym spelled O-T-T-O instead of a A-U-T-O, but I like that too. Nicolaus Otto in Germany refined the internal combustion engine. He patented the technology that is still the underpinning of how our internal combustion engines work today.

GABRIELLA HOPPER: A German engineer named Siegfried Markus was the first to make a gas-powered road vehicle in 1875.

MOLLY BLOOM: In 1886, Karl Benz patented the Motorwagen and was the first to try to sell them to the public.

GABRIELLA HOPPER: Seems like a great idea, right? But at first, no one wanted them.

MOLLY BLOOM: So his wife Bertha decided to help. She took the car for a long distance drive. Along the way, she made repairs to the car on the road. She came up with the idea for brake pads while traveling and made a show of getting more fuel at pharmacies along her route.

GABRIELLA HOPPER: This publicity stunt showed the world how useful these horseless carriages could be.

MOLLY BLOOM: But gas-powered cars were not the only kind of automobiles being developed.

GABRIELLA HOPPER: There were also steam-powered cars and electric ones.

MOLLY BLOOM: To learn more about this rivalry of engines, we're going to drop in on the monthly game night of Stanley the steam car.


GABRIELLA HOPPER: Zippy the electric car.

ZIPPY: Hi, there.

MOLLY BLOOM: And Victor the gas powered car.

VICTOR: Vroom. I'm Victor.

ZIPPY: Coming.

VICTOR: Hey, Zippy.

ZIPPY: Victor, are you ready to lose tonight?

VICTOR: I never lose.

ZIPPY: We'll see about that.

STANLEY: Don't close the door. I'm coming too.

ZIPPY: Stanley, the steam car. Yay. The gang's all here. Come on in.

STANLEY: Hey, Victor. Feeling gassy.

VICTOR: Stan, my man, you know it. Gas is my jam.

ZIPPY: All right, guys, gather round. Tonight's game is?

VICTOR: Car cheesy?

STANLEY: Crazy Eights?

ZIPPY: Settlers of car tan.

STANLEY: That game is hard.

VICTOR: Nice choice, Zip.

ZIPPY: Thanks. I'll start setting up the board, you guys put out the snacks.

VICTOR: No problem. Nuts and bolts go with everyone.

ZIPPY: You bet. But I'm going to juice up with a sip of fresh electricity if you don't mind.

VICTOR: Hey, Stan, what have you been up to lately?

STANLEY: Not much.

VICTOR: Not surprising.

ZIPPY: Victor.

VICTOR: What? It's true.

STANLEY: No, Zippy. It's fine. I haven't been busy. But for the record, Victor, I was in the engine game long before you. Nicolaus Joseph Cuneo. Ring a bell. He built the first automobile in the 1700s, and it was steam-powered.

VICTOR: But then, what happened?

STANLEY: Well, it wasn't our fault the water took so long to heat up and make steam which powered the car. Once we got going, we were quieter and more efficient than the first gas-powered cars.

VICTOR: Yeah, but not for long. I cleaned up my act.

STANLEY: Well, yeah. But we're poised to make a comeback.

ZIPPY: Sure you are, Stanley. Sure, you are. But Victor, we both had you beat for a while there.

VICTOR: Sure. Over 100 years ago. Back when only very rich people could afford cars.

ZIPPY: Hey, man, I was perfect for driving around the city. I didn't make stinky exhaust and I didn't need a hand crank to get started.

STANLEY: Yeah, Victor. Those cranks you guys had were dangerous, flinging people into the air.

ZIPPY: I had fewer parts so I was easier to fix, also way quieter. Electric cars, the number one choice for women. Until World War I.

VICTOR: But then I got my electric starter. See you hand crank. Gas for the win.

ZIPPY: Yeah, well.

VICTOR: Henry Ford figured out how to mass produce us gas-powered cars, making us affordable for everyone.

STANLEY: Whatever.

ZIPPY: I suppose you're going to talk about oil next?

STANLEY: He always does.

VICTOR: Well, oil found in Texas made fuel really cheap too. Yes, oil.

ZIPPY: Exhaust.

VICTOR: Tell me, where were people supposed to recharge on long drives? Electricity wasn't everywhere back then, hey, Zippy.

ZIPPY: Well, yeah. But electricity is everywhere now, Victor. And we really are poised to make a comeback.


ZIPPY: Sorry, Stan.


VICTOR: Is this game ready to play or what?

ZIPPY: Oh, yeah. Are you ready to lose?

VICTOR: I'm very likely.

STANLEY: Can you remind me of the rules again?

ZIPPY: Sure. Well, you need to collect commodities. There's rubber like for your tires, metal like your frame, glass like windows, and plastic for one--


GABRIELLA HOPPER: Internal combustion engines create tiny explosions by combining fuel, air, and heat.

MOLLY BLOOM: This reaction makes the Pistons in an engine move which turn the crankshaft which makes the wheels turn.

GABRIELLA HOPPER: The first automobile was made in the 1700s and powered by steam.

MOLLY BLOOM: Gas and electric came along in the 1800s.

GABRIELLA HOPPER: But gas powered cars became dominant around 1910.

MOLLY BLOOM: That's it for this episode of Brains On.

GABRIELLA HOPPER: Coming up in the road trip series, we'll talk about the future of cars.

MOLLY BLOOM: How they're designed.

GABRIELLA HOPPER: How traffic works.

MOLLY BLOOM: And what happens to our bodies when we ride in the car. Our road trip episodes are going to be coming out fast and furious pun-intended during the month of June. Keep refreshing those podcast feeds and take the whole series on the road with you.

GABRIELLA HOPPER: Wait. Molly, we need to make a pit stop for the Brains Honor Roll.

MOLLY BLOOM: Oh, of course. Here it is.


GABRIELLA HOPPER: Brains On is produced by Mark Sanchez, Sanden Totten, and Molly Bloom.

MOLLY BLOOM: We had engineering help this week from David Green, Roger Smith, Corey Keppel, Steve Griffith, and Eric Bromstad. Many thanks to Tiffany Hanson, Doug Berman, Carolyn Hopper, John Heitmann, Lauren Dee, Eric Wrangham, Anna Reid, Robin Shields, Ryan Musial, Yul Limbfares, Alana and Robert Della'O, and Colleen Gatehouse.

GABRIELLA HOPPER: You can keep up with us on Instagram and Twitter. We're at brains_on.

MOLLY BLOOM: And we're on Facebook too.

GABRIELLA HOPPER: And email your questions, ideas, and mysteries songs and drawings to us any time.

MOLLY BLOOM: We're at hello@brainson.org. Or you can find our mailing address if you want to send us physical mail. That address can be found on our website brainson.org.

GABRIELLA HOPPER: Thanks for listening.

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