cylinder head – direct injection engine Modern PC cylinder head (Mercedes-Benz C-Class) with two-spring injection nozzle and bowl-in piston. Function of the valves and bucket tappe. description ordernumber 1172 see also: common rail injector with magnetic coil at the bottom high-pressure pump for engines with direct petrol injection (GDI) air-mass sensor with hot film two-stage turbocharger (bi-turbo)