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.


If you have a vehicle that needs to be tested for emissions, you might want to check on the condition of your catalytic converter. So what is it and what does it do?

Take diesel-engine technology, throw in a two-stroke cycle, and you've got the basis for the huge engines found in trains and big ships. Learn about the diesel two-stroke engine!

Ever wonder what the difference is between a gasoline engine and a diesel engine? Diesels are more efficient and cheaper to run than gasoline engines. Learn what makes diesel engines different!

Gear ratios are what allow a car to reach a high rate of speed or climb a steep hill. Learn about gear ratios, gear trains and planetary gear systems.

Surprisingly enough, horsepower actually does refer to the power of horses. But over the years it’s become a valuable measurement for all kinds of machinery. Learn how horsepower is calculated and what it means to the automobile industry.

If you have a car chances are you also have a tire-pressure gauge. Learn how this pen-sized device measures air pressure and why the little stick inside doesn't just fly right out the back!

What does that funny "H" pattern on my car's gear shift have to do with my transmission? How does it make the car change gears? And when I mess up and hear that horrible grinding sound, what is actually grinding?