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Infiniti will release the world's first production variable-compression engine when it releases the 2019 QX50midsize SUV sometime next year. Now we have some new details on the innovative new engine, which Infiniti is calling VC-T, for Variable Compression Turbo, after the luxury brand offered a prototype test drive.
We wrote extensively about the complicated technology underpinning the new engine last year. It's the latest novel development that could represent a range-extender, if you will, for the embattled internal combustion engine in an era when automakers and governments are shifting their focus to electric vehicles.
The VC-T is a new inline-four, 2.0-liter that combines the power of a high-performance turbo gasoline engine with the torque and efficiency of an advanced diesel engine, but without the latter's notorious emissions. It features the ability to seamlessly raise or lower the stroke of the pistons in the combustion chamber, depending on the driving conditions it detects and inputs from the driver, to select the best compression ratio—anywhere between 8:1, typical for high-performance engines, and 14:1 for high efficiency. In essence, it delivers the performance of a V6 but is much more efficient, with improved fuel efficiency of between 10 to 15 percent with its best competitors, per Car and Driver.
It's also quieter, more lightweight and compact than V6 engines with comparable power outputs, estimated at 268 horsepower and 288 pound-feet of torque.
In a prototype test drive, Car and Driver writes that the engine "felt very conventional" and responsive, with strong and smooth acceleration. "The only indication you have that the compression ratio is changing is from an indicator in the instrument cluster next to the boost gauge."
The engine is expected to deliver fuel economy gains of 27 percent in combined city-highway EPA rating over the outgoing QX50, which had a 3.7-liter V6. The 2019 model, fitted with the VC-T, should get about 26 mpg in combined fuel economy, and it will get to 60 mph almost one second faster than its four-cylinder counterparts, Nissan's chief powertrain engineer, Shinichi Kiga, told Automotive News.
The VC-T engine is the result of 20 years of development spanning more than 100 prototypes and around 300 patents at Nissan. It hinged on parallel advances in engine-control technologies and the company's invention of the multi-link technology, which raises and lowers the pistons, in 1998. The VC-T features both port and direct fuel injection, the latter of which helps prevent against premature combustion in the cylinder, plus variable valve timing and a four-circuit cooling system. All feed information to the engine's computer, which runs an electric motor that operates the actuator arm that adjusts the piston travel distance and compression ratio. The company says the engine is now in the final stages of development on real roads.
The VC-T will be the only engine option for the 2019 QX50, and it will require premium-grade gasoline. It will also be available solely with a continuously variable automatic transmission, per Automotive News.
I will be interested to see how this engine actually does in real-world service. Will it perform as advertised? Will its real-world fuel consumption match its claims? Will it be reliable? How long before major service is required?
It seems very complicated, mechanically. How much extra mass (weight) does it carry? How much of this is dynamic / rotating mass? How does this extra rotating mass act as a drag on the engine and affect performance, real-world fuel consumption and reliability?
"It's also quieter, more lightweight and compact than V6 engines with comparable power outputs, estimated at 268 horsepower and 288 pound-feet of torque."
"The engine is expected to deliver fuel economy gains of 27 percent in combined city-highway EPA rating over the outgoing QX50, which had a 3.7-liter V6."
"The 2019 model, fitted with the VC-T, should get about 26 mpg in combined fuel economy, and it will get to 60 mph almost one second faster than its four-cylinder counterparts"
I don't think there is or has been any competitors 6 cylinders in the luxury market that only have 268hp for a while. Most are around 300hp or more whether they are turbo or normally aspirated. That power figure is also significantly less then the 3.7 VQ it sounds like they want this 4 cylinder to replace which has 325hp and then they go to say the new 4cylinder is quicker then competitors 4 cylinders, but not 6 cylinders.
Of course a 2.0 liter 4cyl turbo with much less hp is going to be more fuel efficient then a larger 6 cylinder with much more power but it will also likely be slower, not as refined, not as reliable and have its share of compromises.
The new 2.0 VC-T may be the only powertrain for 2019, but I wouldn't rule out the 300hp 3.0TT V6 in the future. This could be a good base engine, as the QX30, Q50, and Q60 all utilize the 2.0T from Mercedes producing 208hp in base form. Yikes
The new 2.0 VC-T may be the only powertrain for 2019, but I wouldn't rule out the 300hp 3.0TT V6 in the future. This could be a good base engine, as the QX30, Q50, and Q60 all utilize the 2.0T from Mercedes producing 208hp in base form. Yikes
Forgot about that, I thought they bumped the power up a little by now.
Forgot about that, I thought they bumped the power up a little by now.
Despite the 2018 Camry getting the revised 2GR-FKS with 301hp (RX got it in 2016 with 295hp) and 8-Speed Auto, the 2018 ES still maintains the older 2GR-FE with 268hp and 6-Speed auto. I'd wager the new 2019 7th Gen ES will get the FKS version.
Despite the 2018 Camry getting the revised 2GR-FKS with 301hp (RX got it in 2016 with 295hp) and 8-Speed Auto, the 2018 ES still maintains the older 2GR-FE with 268hp and 6-Speed auto. I'd wager the new 2019 7th Gen ES will get the FKS version.
I think it will too. It should, the current set up has been in the ES350 for 12 model years.
I wonder how the Infiniti VC-T engine will compare with Toyota's VVT-iW (Variable Valve Timing - intelligent Wide) variable valve-timing system. Nissan implements variable compression ratio through a mechanical system whereas Toyota implements it through valve timing.
Unless production gets delayed it will be Mazda with new 3 who will be the first manufacturer with variable compression engine, they will utilize supercharger instead of turbo though.
Unless production gets delayed it will be Mazda with new 3 who will be the first manufacturer with variable compression engine, they will utilize supercharger instead of turbo though.
The new Mazda engine is a compression ignition engine, NOT a variable compression engine.
I don't like it guys.
It looks too complicated.
Will the redline be as high?
I wonder what the balance and NVH will be like?
With such complexity, will it be durable?
If I had the choice between developing variable compression, or developing electric turbos - I'd go electric turbo.
The ICE is just about to be replaced by Solid State Battery powered EV's anyway...
Last edited by peteharvey; Nov 17, 2017 at 01:34 PM.
Infiniti VC-T (Variable Compression Turbo)
