Turbochargers explained: how boost works

How a turbo works

Exhaust gas spins a turbine, which spins a compressor on the same shaft. The compressor forces more air into the engine, so more fuel can burn and the engine makes more power from the same size.

Key parts

• Wastegate: diverts exhaust to cap boost pressure
• Boost controller: adjusts boost electronically or mechanically
• Intercooler: cools the compressed air for more density
• Blow-off valve: relieves pressure between throttle lifts

Boost and torque

Road cars run 0.5–1.5 bar of boost. More boost usually means more torque, but engines are limited by heat and detonation — that is why tuning raises the risk of engine damage.

Keeping a turbo alive

• Let it idle after hard driving before shutdown — the turbo runs on engine oil
• Change oil on schedule; turbos live and die by oil quality
• Fix boost leaks (hoses, intercooler) promptly
• Use the correct grade oil with the right spec