Cadillac will offer a 420-horsepower twin-turbo V6 in its 2014 CTS.

The announcement comes a few days before the vehicle’s introduction at the New York Auto Show and also clears up a lingering video mystery that was leaked during the Corvette LT1 engine introduction last year. You may remember an EngineLabs video from October showing a demonstration of GM “tilt-stand” dyno test. It was obvious that the technician was working on twin-turbo engine — but which one? Although the video was mistakenly released as part of the Gen V LT1 introduction, it wasn’t clear that the engine on the tilt stand was an LT1, or even a V8.

That same video — or at least one very similar to it — was just released as part of the Cadillac announcement. This twin-turbo V6 displaces 3.6 liters, making it one of the most power-dense engines in the segment at 118 horsepower per liter. The engine is also rated at 430 lb-ft peak torque. Cadillac says 90 percent of the engine’s peak torque is available from 2,500 up to 5,500 rpm.

The twin-turbo is an upgrade of the 60-degree DOHC V6 offered in many of the current Cadillac models, but many components are completely new — such as the block casting. Other new parts include stronger connecting rods, polymer coated pistons with a steel top ring carrier, new charge-air cooler, vacuum-actuated wastegates and new direct-injection system. The turbos are good for 12 pounds of boost, and the engine sports a 10.2:1 compression ratio.

The cylinder heads are also new with high-tumble intake design that complements the turbos and direct injection. Valve sizes are 38.3mm intake and 30.6mm exhaust. The heads also feature hardened AR20 valve-seat material on the exhaust side, and MLS gaskets will maintain sealing under boost.

New head design

“The high-tumble heads were developed with advanced modeling programs that helped us determine the optimal design in less time and with less trial and error,” says Richard Bartlett, assistant chief engineer for the 3.6L engine. “Literally hundreds of simulations were performed to optimize the port flow, injector spray angle and pattern, and piston topology to produce a highly efficient yet powerful combustion chamber.”

The overall turbo setup features a very short path from the turbos to the centrally located throttle body. The charge-cooling heat exchangers can lower the air temperature more than 130 degrees. The twin-brick configuration of the heat exchangers is similar in design and function to the 6.2L supercharged LSA engine.

“The compressors draw their air directly from the inlet box and send their pressurized air through the intercooler basically immediately, giving the new CTS a tremendous feeling of power on demand,” adds Bartlett.

In addition to the vacuum-actuated wastegates and recirculation valves, the engine employs dual mass air flow sensors and an integral inlet air temperature/humidity sensor, a dual-compressor inlet pressure sensor and dual manifold pressure sensors.

Carryover items and features include steel crankshaft, oil squirters on the underside of the pistons and cast aluminum oil pan that contributes to the block and bellhousing rigidity.