How a Car Works · Chapter 02
Chapter 1 followed the energy from tank to road. This chapter looks at the machine that does the converting — cylinders and character, the narrow band of speeds an engine actually works in, and the electric motor that plays by different rules.
· THE CYLINDERS
One cylinder gives one push per two crank turns — usable, but lumpy, like pedalling a bicycle with one leg. Add cylinders and stagger their firing and the pushes overlap into something smooth: a four fires every half turn, a V8 every quarter. How many cylinders and how you arrange them — in a line, in a V, flat — sets the engine’s balance, its size, and the sound it makes at a traffic light.
DEMOCylinder ConfigurationsRun I4, V6, V8 and boxer side by side and watch their shaking forces.TAKEAWAYStaggered firing overlaps the pushes into smoothness; the layout sets balance, size and sound.
· THE NARROW BAND
The engine’s awkward secret: it only works between roughly 1,000 and 7,000 revolutions per minute. Below that it stalls; above it, the pistons’ own inertia starts tearing the machine apart. Even inside that window it pulls strongly only in a band in the middle — while the wheels need everything from a dead stop to motorway speed. That mismatch is why the next two chapters exist at all.
DEMOTorque & PowerShape a torque curve yourself — and see what power really is.TAKEAWAYAn engine works only in a narrow rev band; the wheels need every speed — gears bridge the gap.
· THE TIMING
Every explosion is a small, precisely managed event: the right amount of air (the hard part — fuel is easy), a spark fired before the piston reaches the top so the pressure peak lands just after it, and valves that open early and close late to help a gas with inertia of its own. Get any of it slightly wrong and the engine knocks, overheats, or simply loses its appetite.
DEMOIgnition & KnockChase perfect ignition timing until knock closes in.TAKEAWAYAir is the limit and timing is the craft — the spark fires early so peak pressure lands just after TDC.
· ELECTRIC
An electric motor makes the piston engine look eccentric. No explosions, no idle, no redline worth fearing — just a magnetic field dragging a rotor around, with full twist available from zero speed. That single curve is why an EV needs no clutch and only one gear, and why the next chapter’s whole subject simply vanishes from an electric car.
DEMOThe Rotating FieldWatch three currents make one spinning field.TAKEAWAYElectric motors give full twist from zero speed — no clutch, one gear, no narrow band.
This chapter skates on purpose. The engine library underneath holds the full machinery — the four-stroke cycle with its live pressure trace, crank geometry, valve timing, jets, rockets, electric drive and the marine giants.
FOR THE SELF-CHECK