Market penetration of turbocharging on gasoline engines is relatively low by comparison with Diesel engines even after more than 30 years of use on series vehicles. One reason for this, from the point of view of the customer, is the "turbocharger lag" that can be felt in most cases when accelerating from low engine speeds by comparison with naturally aspirated engines with the same output rating and, consequently, with larger displacement. On Diesel engines for passenger cars, this lesser system-related problem has been impressively solved by the combination of direct fuel injection and variable turbine geometry. Despite various approaches, implementation of this mature turbocharger technology in combination with a gasoline engine failed due to the far-higher exhaust temperatures of the spark-ignited engine and the broader variation in exhaust gas mass flow. Consequently, the fact that these challenges have been overcome and the fact that this technology has been used successfully in series on the new Porsche 991 Turbo can be viewed as a further milestone in turbocharging.
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