Under the Hood

The Under the Hood Channel explores the systems that make your car function correctly. Learn about car parts and systems and how to do routine maintenance.

Topics to Explore

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How do you convert engine torque to horsepower?

When you convert from engine torque to horsepower why is the number 5252 involved?

How Four-Wheel Drive Works

Four-wheel drive can be useful in rough weather or terrain. A lot of drivers use it just to make everyday errands a little more exciting, nothing quite like jumping a few curbs in a supermarket parking lot. Find out how four-wheel-drive systems keep cars on solid footing.

How Car Computers Work

Each year, cars seem to get more and more complicated --cars today might use as many 50 microprocessors! Although they can make it more difficult for you to work on your own car, some microprocessors actually make your car easier to service.

How Fuel Gauges Work

Has your fuel gauge ever read "empty" when you know there are gallons left in your auto's tank? Learn all about how fuel gauges work and how to know when "Empty" means "No seriously get gas."

How Rotary Engines Work

A rotary engine is an internal combustion engine, but it's not like the one in most cars. Learn about the unique rotary setup and how it compares performance-wise to a piston engine.

How Windshield Wipers Work

What began as a hand-cranked system is now automatic and only getting more so: Some windshield wipers can actually sense rain. Learn the mechanincs behind this essential automotive tool.

Why don't they use normal air in race car tires?

Race car tires don't use regular air. Find out what race car teams are using in their tires instead of air.

What makes NASCAR engines different from street car engines?

The engines in today's NASCAR racecars produce upward of 750 horsepower, and they do it without turbochargers, superchargers or particularly exotic components. So how do they make all that power?

How Mufflers Work

Every car out there has a muffler -- it performs the crucial job of turning thousands of explosions per minute into a quiet purr. Mufflers use some cool technology to dim the roar of an engine. Learn the principles that make it work.

How Wires, Fuses, and Connectors Work

Wires fuses and connectors are the kind of thing in your car that you never think about, but they are essential. They're not just there to keep your radio and lights working! Learn why they are so important.

What does it mean when a car has dual overhead cams?

What does it mean when a car has dual overhead cams? Does it matter? Is a car with dual overhead cams better than one with single overhead cams?

How Power Windows Work

Ever wonder what's behind the auto-up feature that can detect obstacles? Power windows are one of those hidden miracles in cars -- they're actually pretty amazing once you learn about them. Find out how power windows operate!

How Cruise Control Systems Work

Cruise control is already an amazing system, and it's evolving into something a lot more powerful. Learn how cruise control works and check out some of the adaptive systems in development.

How Fuel Injection Systems Work

As concerns about vehicle emissions and fuel efficiency have grown, fuel injection systems have risen to the forefront of auto technology. Trying to keep up with new environmental laws, carmakers began installing these systems in all new models.

How Power Door Locks Work

Power door locks used to adorn only luxury cars. Today, these handy amenities are standard on more than half of the cars sold in America. Learn what happens after you push the button!

How Camshafts Work

The camshaft has a huge effect on engine performance. It helps let the air/fuel mixture into the engine and get the exhaust out. Learn all about the camshaft and how a new one can radically change an engine's behavior.

Is there a way to compare a human being to an engine in terms of efficiency

Is there a way to compare a human being to an engine in terms of efficiency? For example can you calculate the equivalent "miles per gallon" (kilometers per liter) rating for a person riding a bicycle?

How Turbochargers Work

When people talk about race cars or high-performance sports cars, the topic of turbochargers usually comes up. A turbo can significantly boost an engine's horsepower without increasing its weight.

How Automatic Transmissions Work

Both automatic and manual transmissions accomplish exactly the same thing, but they do it in totally different ways. And it turns out that the way an automatic transmission does it is pretty amazing!

Why does my manual transmission car make a loud whirring noise in reverse?

Manual transmissions use mostly helical gears, but reverse is a special situation that requires a different type of gear -- a spur gear. Learn why a spur gear makes a loud whirring noise when the car's in reverse.

How Car Cooling Systems Work

A car engine produces so much heat that there is an entire system in your car designed to cool the engine down to its ideal temperature and keep it there. But cooling systems serve other purposes too.

How do tuned intake runners work on your car?

I've heard about tuned intake runners for car engines that provide a kind of turbo-charging effect. How do they work?

How Catalytic Converters Work

A catalytic converter is one of the most important parts of a car's emissions control system. It treats the exhaust before it leaves the car and removes a lot of the pollution. Learn how they work.

How do 30 pounds of air in your tires hold up 2 tons of car?

Learn about tires, tire pressure, and a tire's contact patch.

How can I measure the drag on a car?

I have to think of a way of measuring how much drag is pushing on my mother's car as we are driving on the highway. Do you know how I can make one?