Under the Hood: How Cars Work

Explore how internal combustion engines convert fuel and air into motion via spark or compression ignition, pistons and a crankshaft, turning reciprocating motion into rotary motion to drive wheels.

Explore the core of a spark-ignition engine by examining the cylinder block, head, piston, and combustion chamber, and how the crankshaft, connecting rod, and piston rings transmit motion.

Learn how a four-stroke spark-ignition engine uses a piston, cylinder, and crankshaft to move between bottom dead center and top dead center, defining stroke, bore, swept and clearance volumes, displacement.

Explore how engines are classified by ignition method, crankshaft motion, cycle length, and cylinder arrangement, from spark ignition and diesel to inline, V-type, and horizontally opposed designs.

Explain the four-stroke engine cycle, detailing intake, compression, power, and exhaust strokes, valve timing, spark ignition, and how piston motion drives the crankshaft.

Explore how a four-stroke si engine cycles through intake, compression, ignition, and exhaust, with precise valve timing and piston motion driving spark-ignited combustion.

Two-stroke engines combine intake and compression with exhaust, delivering more power strokes per crank rotation in a compact design, but have reduced stroke length and lower efficiency than four-stroke engines.

Explore how gasoline and diesel engines differ: spark ignition versus compression ignition, diesel cycle with constant pressure heat addition, and the role of fuel injection, compression ratios, and efficiency.

Understand the ignition system in spark ignition engines, generating high voltage from a 12-volt battery via the induction coil and distributor to fire spark plugs at the right compression timing.

Learn how a simple carburetor forms a precise fuel-air mixture and feeds it to the engine via the fuel pump, venturi, throttle, air filter, and accelerator controls.

Explore how air fuel mixtures determine engine performance, from carburetors to fuel injection, and define lean, rich, and stoichiometric ratios, with emphasis on per-cylinder precision and engine load effects.

Explore how air fuel ratio varies across engine modes—starting, idling, cruising, and racing—and why each mode needs a different mixture, from rich to best economy or best power.

Examine how air fuel ratio drives engine power and fuel economy using dual graphs, showing stoichiometric 15:1, best economy near 16–17:1, and best power near 11–12:1.

Explore how a simple carburetor blends fuel and air through a venturi using Bernoulli's principle to regulate the fuel-air mixture for cruising and starting.

Explains how a carburetor uses a venturi to draw fuel via Bernoulli's principle, creating a fuel-air mixture controlled by a butterfly throttle, and discusses why rich mixtures hurt fuel economy.

Explore how fuel system improvements optimize air–fuel mixtures across idling, starting, and full-throttle operation. Examine venturi dynamics, idle air bypass, compensating jets, auxiliary ports, and the accelerating system.

Explore how engine power moves through the drive train—from crankshaft to transmission, drive shaft, and final drive—to the wheels, including front-, rear-, and all-wheel drive layouts and the differential.

Explore the drive train’s subsystems—the final drive, differential, drive shaft, and transmission—and how gears and universal joints transfer torque while the differential adjusts wheel speeds.

Explore how the drive shaft uses universal joints to connect transmission to final drive, and how the transmission uses gears and a clutch to regulate engine RPM and torque.

Explain how the transmission regulates engine torque and reduces rpm through gears to the drive train, including planetary gears, and compare automatic and manual systems with the clutch.

The suspension absorbs bumps with springs and shock absorbers to smooth the ride and insulate the chassis; independent suspension lets each wheel move largely on its own.

Explore how the steering system converts wheel rotation into wheel orientation using a steering column, universal joints, and rack-and-pinion, with power steering reducing driver effort.

Explore the braking system in cars, from hydraulic master and slave cylinders, brake fluid and lines to disc and drum brakes, front-biased braking, calipers, pads, and friction stopping motion.