- Advanced VC-Turbo engine – the company’s world’s first production-ready variable compression ratio engine – is one of the most advanced internal combustion engines ever created
- VC-Turbo engine continuously adjusts its compression ratio to optimize power and efficiency
- New 2.5-liter DOHC inline 4-cylinder makes first appearance in new Altima, offers improved power, efficiency and NVH and contributes to Altima’s low, wide exterior styling
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The VC-Turbo engine offers any compression ratio between 8:1 (for high performance, left in red) and 14:1 (for high efficiency, right in blue). As a result, the engine capacity varies between 1,997 cc and 1,970 cc.
NEW YORK – Reflecting the importance of the Altima to the Nissan brand, the company is making its largest investment ever in a new model powertrain development – introducing for the first time, two completely new engines for one model change.
The new 2.0-liter VC-Turbo, which recently launched as a world’s first technology in the all-new INFINITI QX50 crossover, replaces the previous-generation Altima’s 3.5-liter V6, offering similar performance figures while providing 4-cylinder fuel economy. It will be available on the Altima SR and Platinum front-wheel drive grades.
The new 2.5-liter inline 4-cylinder, which is standard on all 2019 Altima front-wheel drive and Intelligent All-Wheel Drive grade levels, utilizes more than 80% new or redesigned parts. It offers 9 additional horsepower and a fuel economy improvement versus the previous-generation 2.5-liter design.
Importantly, both engines’ short profile designs and low engine mountings contribute to the all-new Altima’s low and wide exterior design, including the lower hood and cowl – as well as reduced levels of noise, vibration and harshness (NVH).
“With its long list of Nissan Intelligent Mobility features such as ProPILOT Assist, this all-new 2019 Altima is the most advanced sedan we have ever built,” said José Muñoz, chief performance officer, Nissan Motor Co., Ltd. “Yet not to be overlooked is the groundbreaking technology under the hood – two new engines that power the Altima’s balanced, confidence-inspiring driving experience.”
World’s first production Variable Compression Turbo engine
Designated as the VC-Turbo, the technology behind the new Altima powerplant was more than 20 years in development and represents a breakthrough in combustion engine design by continually adjusting its compression ratio to optimize power and fuel efficiency. It is projected to offer a double-digit percentage increase in fuel economy.
Assembled in Japan, the VC-Turbo changes its compression ratio seamlessly through an advanced multi-link system, continuously raising or lowering the pistons’ reach to transform compression ratio – offering both power and efficiency on demand. A high compression ratio gives greater efficiency, but in certain applications poses the risk of premature combustion (knocking). A low compression ratio allows for greater power and torque and avoids knocking.
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Above: As the angle of the multi-link arm rotates, the top-dead-center position of the pistons – and the compression ratio — changes. Below: With variable compression, engine displacement varies between an 8:1 ratio for power (illustrated in red on the left) and a 14:1 ratio for efficiency (illustrated in blue on the right).
In operation, the VC-Turbo engine offers any compression ratio between 8:1 (for high performance) and 14:1 (for high efficiency). The engine delivers 248 horsepower @ 5,600 rpm and 273 lb-ft of torque @ 4,000 rpm (premium fuel). The VC-Turbo’s specific power output is higher than many competing turbocharged gasoline engines and comes close to the performance of some V6 gasoline engines. The unit’s single-scroll turbo ensures immediate accelerator responses on demand.
Along with the world’s first multi-link system, the engine features an electric motor with a unique Harmonic Drive reduction gear to manage the variable compression ratio. The electric motor is connected to the Harmonic Drive with a control arm. As the Harmonic Drive rotates, the control shaft at the base of the engine rotates, moving the multi-link system within the engine.
As the angle of the multi-link arms changes, it adjusts the top-dead-center position of the pistons – and the compression ratio with them. An eccentric control shaft changes the compression ratio of all the cylinders at the same time. As a result, the engine capacity varies between 1,997 cc (for a low 8:1 ratio) and 1,970 cc (high 14:1 ratio). The transformative multi-link components are manufactured in high-carbon steel alloy.
The engine also utilizes two combustion cycles, with the electronic variable valve timing allowing the engine to switch between Atkinson and regular combustion cycles. This allows for greater efficiency and optimal performance as the compression ratio transforms.
Compared with the previous-generation Altima’s 3.5-liter V6 engine, the 2.0-liter VC-Turbo requires less space in the engine bay. The integrated exhaust manifold in the cylinder head contributes to the compact engine packaging, improves turbo response and enables the catalytic converter to heat up quickly for lower emissions. The engine also contributes to lower NVH levels.
The VC-Turbo engine uses both multi-point injection and gasoline direct injection to balance efficiency and power in all conditions. Gasoline direct injection improves combustion efficiency and performance, and enables the engine to avoid knocking at higher compression ratios.
The multi-point injection system mixes fuel and air earlier, enabling complete combustion in the chamber for greater efficiency at low engine loads. The engine switches between both at regular engine speeds, with both sets of injectors able to work in conjunction under higher loads.
In addition, low-friction mirror bore coating contributes to a 44% reduction in cylinder friction, allowing the engine to rotate more smoothly. The coating is applied to the cylinder walls by a plasma jet, then hardened and honed to create ultra-smooth cylinder walls. And finally, a two-stage variable displacement oil pump raises the oil pressure as engine speeds rise and the compression ratio lowers.
Altimas equipped with the VC-Turbo (SR 2.0L and Platinum 2.0L grades) include a meter in the instrument panel’s 7-inch Advanced Drive Assist Display so the driver can see, as well as feel, the control state of this unique technology while driving.
“This advanced new VC-Turbo engine can balance the engine character between economy and high power by accelerator pedal operation only,” added Muñoz. “And, with no special maintenance required, drivers can just enjoy the driving experience without thinking about all the amazing things happening under the hood.”
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New standard 2.5-liter 4-cylinder engine
Standard on all 2019 Altima grade levels is the new 2.5-liter DOHC inline 4-cylinder direct injection engine. The engine is rated at 188 horsepower @ 6,000 rpm (versus the previous 2.5-liter’s 179 hp) and 180 lb-ft of torque @ 3,600 rpm (versus the previous 177 lb-ft). The new engine inherits the good combination of high output and low fuel consumption of the previous, robust QR25DE engine, which has been utilized in many Nissan vehicles worldwide.
The new 2.5-liter engine features 80% new or redesigned parts. Key changes to the engine’s design include a thermal-insulated resin intake port, Direct Injection Gasoline (DIG™) system, variable tumble control valve, mirror bore cylinder coating, variable displacement oil pump, intake e-VTC and cooled external EGR.
The Direct Injection Gas (DIG™) system provides better wide-open throttle performance and improved fuel economy and emissions performance (versus a non-direct-injection system) by reducing engine knock, improving combustion stability and offering precise injection control.
The thermal insulated resin intake port, a world’s first, uses an air layer to help keep fresh intake air cold, benefiting power, torque and fuel economy. The resin port is inserted into the cylinder head port to create the air layer.
In addition, with the cylinder head’s integrated exhaust manifold, the catalyst can activate faster during cold engine start conditions, due to the short exhaust passage length from combustion chamber to catalyst. The theoretical air-fuel ratio area can be expanded at hot engine conditions due to low exhaust gas temperature provided by the large water jacket around the exhaust port.
More than just the gains in horsepower and torque, the new engine offers significant improvements in noise, vibration and harshness, along with enhanced fuel economy and cleaner emissions.
It also has a lower profile through adoption of a “reverse” cylinder head with integrated exhaust manifold and low engine mounting into the new platform’s engine bay for quieter operation. The new low engine mounting design helps reduce vibration noise by five decibels. The new engine is assembled in Decherd, Tennessee.
All 2019 Altima models, including both engine configurations, come equipped with a standard, advanced Xtronic transmission. For 2019, the Xtronic transmission receives an expanded lock-up area for improved efficiency. Paddle shifters are available with the Altima SR grade.
All 2019 Altima models, including both engine configurations, come equipped with a standard, advanced Xtronic transmission. For 2019, the Xtronic transmission receives an expanded lock-up area for improved efficiency. Paddle shifters are available with the Altima SR grade.
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Contact
Josh Clifton
Senior Manager, Product Communications, Car SUV and Technology
Office: 615-725-1767
josh.clifton@nissan-usa.com
Kyle Torrens
Specialist, Production Communications, Car, SUV and Technology
Office: 615-725-4019
kyle.torrens@nissan-usa.com
Dan Passe
Nissan Global Communications
dan-passe@mail.nissan.co.jp
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