Infiniti Reveals Full VC-Turbo Details

Infiniti uses its 2016 Paris auto show stage to reveal further details of its new variable-compression 2.0L turbocharged 4-cyl., the VC-Turbo.

Infiniti announced what it says is a world-first engine last month, promising, “The power of a high-performance 2.0L turbo gasoline engine with a high level of (diesel-like) efficiency at the same time” and compression ratios of 8:1 to 14:1 achieved by varying the height of pistons in their combustion chambers.

The Nissan luxury brand says the VC-Turbo will arrive in the market in new Infinitis in 2018 and with targeted power output of 268 hp and 288 lb.-ft. (390 Nm) of torque.

“The VC-Turbo engine will be comparable to certain 6-cyl. gasoline powertrains for performance, while significantly outperforming them in efficiency,” Infiniti says. Engineers target a 27% improvement in fuel efficiency over gas V-6s.

Noise and vibration levels lower than conventional internal-combustion engines also are promised, as is a design lighter and more compact than a V-6’s.

Infiniti vows the constantly optimized compression ratio plus direct fuel injection solves high-compression engines’ so-called knocking problem caused by air and fuel combusting early in the chamber.

A multilink technology, with piston-connecting rods almost vertical during the combustion cycle, was created in 1998 and is one of 300 technologies Infiniti says it has patented for the VC-Turbo.

Another patented technology is an electric motor connected to what Infiniti calls the Harmonic Drive reduction gear with a connecting control arm.

“The Harmonic Drive rotates according to the compression ratio required, which rotates the control shaft at the base of the engine and, in turn, moves the multilink mechanism.

“Changing the multilink angle adjusts the height of the top-dead-center of the pistons, varying the compression ratio. An eccentric control shaft varies the piston stroke position for all four cylinders at the same time,” Infiniti says.

The multilink-created reciprocating motion brings about a smooth-running engine with low levels of vibration, negating the need for balance shafts. Engine-vibration noise for the VC-Turbo is at 10 decibels compared with three dB for Infiniti’s 3.5L VQ V-6, the benchmark V-6 for VC-Turbo development.

Formula 1 Input

In its 20 years in development, Infiniti says it made more than 100 VC-Turbo prototypes on which it put 1.9 million test miles (3 million km) and 30,000 hours on test beds. Late-stage testing involved Renault’s Sport Formula 1 team, which helped uncover a small bearing vibration at the highest engine speeds under certain conditions.

In addition to DI, the VC-Turbo also uses multipoint injection, allowing for a quicker air-fuel mix at low engine loads.

Immediate acceleration is made possible by a wide-range single-scroll turbocharger.

Friction reduction is achieved with mirror-bore cylinder coating. Already employed in Infiniti’s new 3.0L twin-turbo V-6, the smooth wall cuts cylinder friction 44%, Infiniti says.

An integrated exhaust manifold, electronically controlled wastegate actuator, variable-displacement oil pump and high-capacity intercooler are some of the VC-Turbo’s other technologies.

The engine’s block and cylinder are made of lightweight aluminum alloys and the multilink components are high-carbon alloy steel.

Infiniti says “significant powertrain innovations” will occur in its next growth phase, with the V-6 and V-8-centric brand noting it improved its U.S. CAFE rating 36% from 2005-2014.

Also on Infiniti’s Paris stand is the concept QX Sport Inspiration, a hint at a successor to its midsize QX70 CUV and which has been tweaked (dark-brown interior leather, headlamp chrome detailing, larger, bronze-color wheels, matte gray exterior) since its April debut at the Beijing auto show.

A refreshed Q50 sport sedan, which for ’17 adds new gray or brown leather upholstery, open-pore dark wood veneer, a 13-speaker Bose sound system, new electronic architecture and a new red paint shade done via machine and manual application, also is on display.

Infiniti, which is trying to expand beyond the U.S. to become a global luxury brand, sold more than 110,000 units in first-half 2016, up 7% from the same period year-ago.

In the U.S., still Infiniti’s biggest market, sales were flat January through August at 85,362, WardsAuto data shows.

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