Massive diesel torque

Mercedes-Benz is introducing its compact and a more powerful twin-turbo inline four in July this year. The C-class will now be powered by the 250 CDI motor, the same engine doing duty in the E-class, taking power upto 201bhp and a huge 51kgm of torque.

The twin sequential turbos used on this engine are not identical, however. Engineers have used a combination of a small and large turbo, placed in series, to deliver the best of both worlds. The smaller turbo is used to deliver high pressure boost and the larger one takes care of low pressure induction.

At low speeds, a bypass duct in the high pressure turbo allows only the low pressure turbine to be spun. But as soon as higher speeds are reached, both work together for greater boost and performance.