Small sparks. Big ideas.
Let’s find out what makes a car go.
Four steps, over and over.
A piston slides inside a cylinder. A connecting rod links it to a crankshaft, changing up-and-down movement into rotation.
Breathe in.
The intake valve opens. The piston travels down, drawing air and fuel into this simplified gasoline engine.
Simplified teaching diagram. Valve timing and fuel injection differ between real engines. One full cycle takes two crankshaft revolutions.
What does “rev” mean?
To rev an engine means to increase how quickly its crankshaft turns. We measure that in revolutions per minute, or RPM.
In a four-stroke engine, each cylinder has one power stroke every two revolutions. More cylinders or higher RPM usually means more firing pulses each second. Engine layout, exhaust design and displacement also shape its voice.
Try five real engine recordings, from a four-cylinder Volvo to a V12 Lamborghini. The pedal blends and changes the pitch of recorded samples; open the original recording to hear the car at its captured speed.
Give it a rev.
Pick an engine. Tap Start sound, then hold the pedal.
Drag the dial for a steady RPM. Arrow keys work too.
Sound off — tap Start sound.
The pedal changes the speed of recorded engine samples. RPM and redline are simulated. Sound stops after 20 seconds.
Recording credits
Porsche Cayenne steady-RPM recordings · GameAudioGDC 2020 by Soundholder · Sonniss GameAudioGDC project license. Recordist-prepared steady-RPM loops, downmixed to mono, resampled to 44.1 kHz, and scaled by constant gain. The interactive pedal changes sample speed and blends the two recordings. Displayed RPM is simulated. No generated tone, cycle averaging, or repeated acceleration excerpt. The source license permits use within finished interactive projects; these recordings are not offered as a sound-effects download.
What about electric cars?
Gasoline
Fuel burns inside the engine. Expanding gases push pistons, which turn a crankshaft.
Electric
A battery supplies electricity. Magnetic forces inside a motor create rotation. No combustion or exhaust is needed at the motor.
Hybrid
An engine and an electric motor work together. Many hybrids recover some energy when slowing down.
Meet the first Prius →Words worth knowing
Torque is a turning force. Think of pushing on a wrench.
Power describes how quickly work is done. Horsepower and kilowatts are ways to measure it.
Displacement is the volume the pistons sweep through. More liters do not automatically mean a faster car.
Turbocharger uses exhaust energy to drive a compressor that pushes more air into the engine.
Learn more with a grown-up: U.S. Department of Energy · How cars work · NASA · Four-stroke engines