M271

Replacing the M111 in 2002 and built at Untertürkheim, the M271 spent thirteen years being force-fed by whichever method was current. It started as the Kompressor engine — belt-driven supercharger, intercooler, port injection, fracture-split forged rods — and it is why a whole generation of C-, E-, CLK- and SLK-badged cars carried that word on the boot lid. In 2003 the same block took CGI stratified-charge direct injection, sold for barely two years. In 2009 the M271 Evo swapped the supercharger for a turbocharger while keeping direct injection, and the family topped out at 204 PS.

Its reputation is mixed and very specific. The single-row timing chain runs against cast-iron camshaft adjuster sprockets, whose teeth wear; the chain then stretches until it can jump, and the resulting fault codes are familiar enough that specializts sell re-hardened replacement sprockets. Mercedes-Benz gave the successor M274 a duplex chain. Away from road cars it had a cleaner life: HWA built a naturally aspirated two-liter version into the Mercedes-Benz Formula 3 engine, which carried championship-winning drivers across Europe and well beyond it for years.