Advantages of twin-scroll turbocharger

Advanced boosting technology to help OEMs meet strict emission regulations

Turbocharged engines of the past have perennially suffered from ‘lag’, a delay in response to a driver input request for increased performance by way of an accelerator pedal depression. This occurs as a result of the time taken for the turbocharger to ‘spool up’ (exhaust gas impeller to increase in speed) and drive induction air into the cylinders at higher pressure. Engines of today are equipped with advanced forced induction technologies and control strategies, which have improved boost response. Automakers attempted to reduce the lag with the incorporation of multi-stage sequential turbochargers, which inconveniently increased cost and mechanical complexity, meaning they were typically limited to more high-performance applications. Twin-scroll turbochargers attend to this issue by separation of the exhaust manifold ports in to two pairs whose exhaust gas pulses interfere with each other. The design here channels two-cylinder outputs to each side of the turbine inlet so that the kinetic energy from the exhaust gases is recovered more efficiently by the turbine, with more regular, smaller pulsations of exhaust gas rather than larger, less frequent inputs. The technology has been around for more than two decades under high-performance upgrades for racing leagues and after-market.