Infiniti to Release World’s First Production Variable-Compression Engine in 2018 QX50
Compact Crossover Gets Two Compression Ratios, Turbocharger for Power and Efficiency
In order to improve power, efficiency, and emissions, automakers have resorted to engine downsizing and unique technologies. For example, Ford markets its 3.5L EcoBoost V-6 as its top-spec engine in the F-150, while General Motors and Ram use gasoline direct injection and light-duty diesel motors in some of their products to improve efficiency. The luxury market isn’t immune either, with BMW replacing naturally aspirated six-cylinder engines for smaller, turbocharged I-4s. Such practices are becoming commonplace, and Infiniti is no exception.
In fact, the Japanese luxury automaker might even be considered an innovator, thanks to its newest engine design that boasts, among other things, a variable compression ratio. Called VC-T, the 2.0L turbocharged I-4 revealed yesterday sports unique internals that see the piston attached to the crankshaft via a multi-link pivot, which in turn attaches to an actuator arm and harmonic drive that move the piston’s travel up or down within the cylinder. The whole process is difficult to describe, but Infiniti’s patent drawings and one YouTuber’s informative video (embedded below) help us laypeople understand how it all works.
When the engine-management system detects a need for low-performance operation, the VC-T actuates its high-compression phase, optimizing combustion and improving efficiency when the turbo’s boost isn’t needed. But when it’s time to start spooling, the engine phases into low-compression mode, helping prevent engine knock as the turbocharger dumps air into the pistons. The system is said to offer infinite adjustment between compression ratios of 8.0:1 and 14.0:1. Infiniti claims more power and torque than the engine in its 3.5L QX60 crossover (265 hp and 248 lb-ft), and we’ll be surprised if the new-tech engine doesn’t produce 300 hp or more.
VC-T will get its public debut in September at the Paris Motor Show, and rumor has it the engine will show up in the next-generation QX50 midsize crossover (previewed by the QX Sport Inspiration concept). If equipped with VC-T technology, the QX50 would produce more power than the Audi Q3 2.0T, BMW X3 xDrive28i, and Lincoln MKC 2.0T.
Sources: Infiniti, Automobile