Nissan revolution: could new petrol engine make diesel obsolete?Japanese automaker Nissan Motor Co has come up with a new type of gasoline engine it says may make some of today's advanced diesel engines obsolete. The new engine uses variable compression technology, which Nissan engineers say allows it at any given moment to choose an optimal compression ratio for combustion - a key factor in the trade-off between power and efficiency in all gasoline-fuelled engines. The technology gives the new engine the performance of turbo-charged gasoline engines while matching the power and fuel economy of today's diesel and hybrid powertrains - a level of performance and efficiency the conventional gasoline engine has so far struggled to achieve.
The potential breakthrough technology comes at a time when diesel engine technology has been tarnished by Volkswagen's emissions cheating scandal. We believe this new engine of ours is an ultimate gasoline engine that could over time replace the (advanced) diesel engine of today," Kinichi Tanuma, a senior Nissan engineer who leads product development for the premium Infiniti brand, told reporters at a pre-launch briefing last month. "Increasing the fuel efficiency of internal combustion engines is critical to automakers. Not all consumers will accept a battery electric vehicle solution."
The new Variable Compression-Turbo (VC-T) powertrain, expected to be officially unveiled at next month's Paris motor show, will initially be showcased in an Infiniti car to be unveiled next year. The turbo-charged, 2-liter, four-cylinder VC-T engine averages 27 percent better fuel economy than the 3.5-liter V6 engine it replaces, with comparable power and torque. Nissan says the new engine matches the diesel engine in torque – the amount of thrust that helps determine the car's acceleration. The engine is also cheaper than today's advanced turbo-charged diesel engines. They said it should also meet nitrogen oxide (NOx) and other emissions rules in certain markets without requiring costly treatment systems.
Game Changer: Infiniti’s VC-T Variable Compression EngineInfiniti will launch the world’s first production continuously variable compression ratio engine in 2018. The engine, a 2.0-liter turbocharged inline four called VC-T, will debut in the new QX50 crossover in 2018. Nissan engineers have reportedly been working on the engine concept for more than 20 years. Engineers say the system allows the compression ratio of the Infiniti VC-T engine to be seamlessly and continuously varied between 8:1 and 14:1. The engine will adopt a lower compression ratio under hard acceleration or heavy loads to allow the turbocharger to deliver maximum boost, and move to a higher compression ratio on light throttle to allow for fuel-efficient lean-burn running. The engine, which uses both port and direct injection, will switch between Atkinson and regular combustion cycles without interruption.
Infiniti claims the 2.0-liter VC-T engine will deliver more than the 265 hp and 248 lb-ft of torque developed by the 3.5-liter V-6 currently available in the QX60 crossover, with a 27 percent boost in fuel efficiency. Variable compression ratio engines have existing in engineering labs for decades, but Infiniti will be the first to have a production version with a continuously variable compression ratio. The VC-T engine will be used in other Infiniti models, and also in future Nissans.
Allowing its premium Infiniti brand to debut the engine suggests Nissan is preparing to bet big on variable compression ratio technology, especially in Europe. Engineers say the engine is cheaper to build than a Euro 6 compliant diesel, and it won’t be subject to the growing backlash against diesels in Europe because of increased concerns over particulate emissions.
So you get the power and efficiency of diesel but without the added cost and emissions? Sounds like a sweet deal.