2005 Mercedes-Benz SLK 320 CDI Tri-Turbo Vision Concept

Benz likens the Tri-Turbo forced induction system to a sort of two-stage supercharger for its diesel engine. The three

Three turbochargers minimize turbo lag, maximize performance and demonstrate the potential of advanced diesel technology. (Photo: Mercedes-Benz Canada)

turbos are spread around the engine; two smaller units are located outside the cylinder banks, while the third, larger unit is fitted snugly between the 'V' of the cylinders.

At lower engine speeds, all three turbochargers spin to produce power, but most of the work is done by the quick-spooling, lower-pressure smaller turbos. When engine speeds rise and a more constant air flow supply is created, the workload is shifted to the larger turbo, which supplies greater boost and a massive wave of torque. The two smaller turbos are then shut down via a bypass system. To meet the demands of the high-performance engine, a larger

With a top speed that's electronically limited to 250 km/h (155 mph), the diesel SLK is about as fast as oil burners come. (Photo: Mercedes-Benz Canada)

intercooler and larger pipes have been installed to improve the flow of charge-cooled air and the waste exhaust.

The specs associated with this 3.0-litre powerplant are nothing short of phenomenal. Benz rates the engine at 286 horsepower, which is only slightly greater output than its stock SLK350 provides, but torque is rated at an amazing 464 lb-ft, which is enough to propel the compact SLK to 100 km/h in a scant 5.3 seconds, just 0.4 seconds slower than the gasoline V8-powered SLK 55 AMG. Equally impressive is the Tri-Turbo's standing kilometre dash, which is achieved in a mere 24.4 seconds. With a top speed that's electronically limited to 250 km/h (155 mph), the diesel SLK is about as fast as oil burners come.