'Big-Block' Versus 'Medium-Block' Diesels

      In currently produced heavy truck diesels, "big-block" engines - by generally accepted definition - include 15-liter models like Caterpillar's C15 and Cummins' ISX, as well as Detroit Diesel's 14-liter Series 60 and Volvo's new 16-liter D16D.
      "Medium-block" diesels include Cat's C11 and C13, Cummins' 11-liter ISM, Detroit's 12.7-liter Series 60, Mack's entire 12-liter ASET range (which carry subtitles for various applications), Mercedes-Benz's 12.8-liter MBE4000, and Volvo's D12.
      Distinctions and terminology vary. International, which builds its own medium- and medium-/heavy duty diesels (the DT466 and DT/HT570), buys Cummins' ISM and ISX and Cat's C11, C13 and C15 engines for many of its Class 8 trucks and tractors, but calls them all big-bore power.
      Mack and Volvo have espoused 12 liters as the optimum engine displacement for years, and they haven't referred to these as medium-block engines. Both offer models with a big-block-like 460 horsepower and 1,650 lbs.-ft. of torque, enough for the vast majority of its customers' applications. For the few customers who want more, Mack and Volvo offer the Cummins ISX; it's more popular among Volvo's customers than Mack's.
      Now Volvo has the D16, and is changing its marketing approach to focus on the customers who can efficiently use this engine. These will include the heavy guys who run fast, and heavy machinery and equipment haulers. In '07, Mack and Volvo - both owned by Volvo AB of Sweden - will begin sharing a new family of diesels that will include 11- and 13-liter models as well as the 16, each set up with different characteristics for Mack and Volvo operators. So right-sizing will become even more important.

Equipment Continued...