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    • Infiniti creates a variable compression ratio motor (VC-T) able to switch from 8.0:1 to 14.0:1 compression on the fly thanks to witchcraft

      Variable compression ratios on the fly? Yes. You must now be thinking this is witchcraft or that Infiniti returned from the future with crazy technology. Well, the idea is not as crazy as it seems. Saab (yes, Saab) was working on a production motor with variable compression ratio technology.


      What happened? GM bought them and shut the program down. It is unfortunate this technology never saw the light of day:


      It was not just Saab that was working with variable compression but Mercedes as well in their F700 Diesotto concept car:


      Concepts are one thing. Production engines are something else entirely. Infiniti will be the first company to market a variable compression engine. It's only taken two decades to get here.

      The Infiniti engine will vary from 8.0:1 to 14.0:1 on the fly depending on driving conditions. This VC-T (Variable Compression-Ratio Turbocharger) motor will be a 268 horsepower and 288 lb-ft of torque 2.0 liter four-cylinder.

      How does this system work? Like this:


      Basically, the height the piston reaches is adjusted. An actuator arm moves a shaft which then forces the rod and piston higher or lower depending on what the ECU tells it to do.

      Now, this sounds great on paper. The problem? How strong is this engine really? The technology employed in a four-cylinder making under 300 horsepower is great but Infiniti is not scaling the technology to six or eight cylinder motors. Maybe they will in the future but from a tuning perspective this technology seems to offer needless complexity and more weight. From a fuel efficiency perspective, it makes a ton of sense.

      Expect to see the first VC-T engine in 2017 under the hood of the QX50.

      Press Release:

      INFINITI VC-T: The world’s first production-ready variable compression ratio engine
      INFINITI will present VC-T (Variable Compression-Turbocharged), the world's first production-ready variable compression ratio engine and one of the most advanced internal combustion engines ever created, on September 29 at the 2016 Paris Motor Show (Mondial de l'Automobile).

      More than 20 years in development, INFINITI's new four-cylinder turbocharged gasoline VC-T engine represents a major breakthrough in internal-combustion powertrain technology.

      "VC-T technology is a step change for INFINITI," said Roland Krueger, president of INFINITI Motor Company. "It is a revolutionary next-step in optimizing the efficiency of the internal combustion engine. This technological breakthrough delivers the power of a high-performance 2.0-liter turbo gasoline engine with a high level of efficiency at the same time."

      VC-T technology signifies a new chapter in the story of the internal combustion engine – engines are no longer limited by a fixed compression ratio. The ingenuity of VC-T engine technology lies in its ability to transform itself and seamlessly raise or lower the height the pistons reach. As a consequence, the displacement of the engine changes and the compression ratio can vary anywhere between 8:1 (for high performance) and 14:1 (for high efficiency). The sophisticated engine control logic automatically applies the optimum ratio, depending on what the driving situation demands.

      VC-T technology delivers multiple customer benefits including significantly reduced fuel consumption and emissions, greatly reduced noise and vibration levels; it is also lighter and more compact than comparable conventional engines.

      More information on the world-first VC-T engine will be presented by INFINITI at Mondial de l'Automobile on September 29, with the company's press conference taking place at 12:30 p.m. local time.

      This article was originally published in forum thread: Infiniti creates a variable compression ratio motor (VC-T) able to switch from 8.0:1 to 14.0:1 compression on the fly thanks to witchcraft started by Sticky View original post
      Comments 5 Comments
      1. Stevenh's Avatar
        Stevenh -
        I love the idea, but I wouldn't touch this technology for a few years and until after I see a LOT of cars reliably cross the 100k mile mark. Seems like an opportunity for lots complex and expensive parts to break. Variable compression flux capacitor goes out? Well, no in the US knows how to work on that so we'll go ahead and send you a freight motor from Japan.
      1. Sticky's Avatar
        Sticky -
        I wouldn't want it in my motor but it's pretty cool tech nevertheless.
      1. MSIZZLE's Avatar
        MSIZZLE -
        is this a "because i can" type of thing? Little 2.0 engines are at the 40mpg point already, how much more does this get you to justify the expense???
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by MSIZZLE Click here to enlarge
        is this a "because i can" type of thing? Little 2.0 engines are at the 40mpg point already, how much more does this get you???
        They didn't develop it for 20 years for fun.
      1. Mortagnais's Avatar
        Mortagnais -
        There is also a french company which started 20+years ago to develop such a thing, with slight technical differences :
        https://www.mce-5.com/en/disruptive-...ve-powertrain/
        I had a few colleagues working on it from 2005 on...but it sounds like they are just starting it in China.