Whatever you do, don?t call it Northstar. According to John Rydzewski, assistant chief engineer of the all-new 550-hp Cadillac V-8 engine, the powerplant was called many things during its roughly four-year development, but in the end they?re just calling it exactly what it is: twin-turbo 4.2-liter V-8. No funny alphanumerics or drawing on history here. Considering the Cadillac brand’s devotion to letters and numbers for all of its nameplates except the Escalade, we?re a little surprised something like NS2 didn?t wiggle its way into its lexicon.
General Motors devotees will remember the Northstar as the first and?aside from the engine powering the limited first-gen Corvette ZR-1?the only DOHC V-8 that GM has produced. It was a silky-smooth mill in its day that served in the top-range Caddys, Oldsmobiles, Pontiacs, and Buicks. But this new engine isn’t much like that one.
Starting at the top, it certainly looks different. That?s because the rotocast aluminum heads have a reversed flow, creating what is called a ?hot V,? to feed two Mitsubishi Heavy Industries TD03 twin-scroll turbochargers nestled in the valley of the engine. This arrangement is common among the German automakers, with Audi, Porsche, Mercedes, and BMW all running hot-V twin-turbo V-8s. Positioning the turbos as close to the exhaust ports as possible is advantageous to response and efficiency, and it also simplifies exhaust plumbing to allow the turbos to receive even exhaust pulses from a cro...