Mazda Announces It Has Solved Gasoline’s Pre-ignition Problem with High Compression

Discussion in 'In the News' started by xcel, Aug 8, 2017.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    [​IMG] Compression Ignition’s efficiency and simplicity on gasoline is near commercialization. Maybe?

    Wayne Gerdes – CleanMPG – Aug. 7, 2017

    2019 SKYACTIV-X

    Fingers crossed… Again. :)

    Mazda just announced, “Sustainable Zoom-Zoom 2030,” a long-term vision for technology development to 2030. Within this announcement, they stated they have created and will introduce a next-generation engine called SKYACTIV-X, the world’s first commercial gasoline engine to use compression ignition in 2019.

    SKYACTIV-X Engine

    According to the company’s release, SKYACTIV-X is/will be the world’s first commercial gasoline engine to use compression ignition, in which the fuel-air mixture ignites spontaneously when compressed by the piston. A proprietary combustion method called Spark Controlled Compression Ignition overcomes two issues that had impeded commercialization of compression ignition gasoline engines: maximizing the zone in which compression ignition is possible and achieving a seamless transition between compression ignition and spark ignition.

    This new combustion engine combines the advantages of gasoline and diesel engines to achieve outstanding efficiency and power.

    Compression ignition with a supercharger improves efficiency, engine response, and in particular, increases torque between 10 and 30 percent over the current SKYACTIV-G gasoline engine family.

    Compression ignition makes possible a super lean burn that improves engine efficiency up to 20 to 30 percent over the current SKYACTIV-G gasoline engine of the same displacement. SKYACTIV-X even equals or exceeds the latest SKYACTIV-D diesel engine in fuel efficiency!!! The engine is still under development and figures are subject to change.

    With high efficiency across a wide range of rpms and engine loads, the engine allows much more latitude in the selection of gear ratios, providing both superior fuel economy and driving performance.

    Homogeneous Charge Compression Ignition (HCCI)

    Let us assume Mazda is using HCCI using conventional gasoline in an engine without spark. Meaning the heat of compression > 15:1 compression ratios are high enough to auto ignite the air-fuel mixture in a controlled manner which in turn creates the downward driving force on the piston. Because HCCI injects fuel later in the compression stroke, combustion normally occurs at the boundary of the fuel and air, producing higher emissions, but allowing a leaner and higher compression burn, producing up to 30 percent more efficiency than a std. gasoline engine. Think TD vs a std. SI ICE.

    Controlling HCCI through a range from idle to full power is a bitch however. The trick is to control the HCCI process to achieve the efficiency, extremely low NO, and run over wide load and speed ranges.

    Homogeneous mixing of fuel and air leads to cleaner combustion and lower emissions. Because peak temperatures are significantly lower than in typical SI engines, NOx levels are almost negligible. Additionally, the technique does not produce soot so no DPF would be required.

    The hard parts include how to create the auto ignition temperature from a cold start, a much tighter load range where the lean fuel-air can provide usable power due to in-cylinder pressure restrictions, and both CO and HC pre-catalyst emissions are higher due an incomplete combustion event thanks to how fast it occurs and the low in-cylinder temperatures.

    So how is it controlled to allow cold starts, a wide powerband, and low emissions of all types? I have no idea what Mazda is doing?

    While we still await the 2.2L SKYACTIV-D with SCR and a DPF, maybe the SKYACTIV-X using HCCI possibly will be offered almost immediately - as a 2019 - in the CX-5 or new Mzda3 instead? A super lean mixture usually introduces sky-high NOx output which may indicate the need for a gasoline SCR solution to cure that hurdle. Except with an HCCI off-shoot...

    And what about its drivability near idle, high torque at low RPM, or max power at WOT? Mazda has a penchant for curing combustion problems. Cold temperature starting? Does it use very expensive 30k psi CI injectors or more std. 2.7k SI ones?

    Like the 14:1 CR on gasoline in their European and Asian SKYACTIV-G engines - 13:1 here, maybe they have just done it again?
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  2. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    I wonder where spark ignition comes in with Mazda's technology? Compression ignition for the long haul and overall efficiency; spark ignition for edge conditions that require a little "cheat?" Just thinking out loud...
    xcel likes this.
  3. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Will they be able to do "super lean burn" without excessive NOX emissions ? Will the supercharged version be efficient ? Or just powerful ? And screw the CX-5 , can we have a 1.5L version in a 3 ? Okay, I know I'm asking for a lot. But they seem to be promising a lot (20-30% more efficient than SKYACTIV-G). This could be a good thing. You brought up a number of other good questions ; hopefully Mazda engineers are as good as I think they are.
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  4. Jay

    Jay Well-Known Member

    This is really exciting! I remember reading about Honda's experiments with compression ignition 2-stroke motorcycle engines around the turn of the century. Apparently those efforts stalled because of the very small window of load and rpm that the system worked. As I google around I'm reading that Skyactiv-X uses spark ignition at higher loads and compression ignition at lower loads. Just the opposite of what I expected. I also read that the engine may debut in the next generation Mazda3 due in late 2018. That would be awsome! The end of the filthy diesel engine is near and it can't come soon enough, IMO!
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  5. Jay

    Jay Well-Known Member

    Here's a good overview of the technology with reports on progress by various automakers:

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  6. seftonm

    seftonm Veteran Staff Member

    I'm not up to date on current emissions standards. How do EPA NOx limits compare to Euro 6? I see this engine being available in Europe where there is focus on reducing CO2. If the EPA limits are more strict on NOx than in Europe, then we may not be as likely to see this engine here anytime soon.
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  7. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    From the article Jay referenced...
    I like the sound of that! :)
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  8. Jay

    Jay Well-Known Member

    from the link above. This gasoline compression engine technology is really the holy grail of internal combustion. If Mazda has a practical engine--GO MAZDA!
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  9. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    I asked two of the Mazda PR and Tuning people I know if this is an HCCI offshoot. We probably will not receive an answer to that for a few months and the next SKYACTIV-X release but I am hopeful.

    BillLin likes this.
  10. Carcus

    Carcus Well-Known Member

    3 year old C&D article says they won't downsize HCCI because they can't flow enough air, .... but then again, I don't see the word "supercharger" mentioned in the article either ...

    "Surprisingly, Mazda is passing on today’s popular trend of downsized, turbocharged engines—say, a 1.4-liter turbo instead of this 2.0-liter. The company says the next generation of gasoline engines, which will employ HCCI (Homogenous Charge Compression Ignition)—essentially firing a gasoline engine like a diesel, without using the spark plugs—will erode the benefits of downsized engines. Smaller engines reduce pumping losses by operating at a higher load (the throttle is open further) more often. In the same way, HCCI engines will have to flow more air to realize the fuel-saving, lean-combustion benefits of that cycle. Mazda claims that if it downsized the Sky family of engines they wouldn’t be able to flow enough air for HCCI without upsizing once again. Plus, as Mazda rightly points out, adding a turbocharger and an intercooler is quite a pricey proposition."

    //I'm guessing an HCCI Mazda3 wouldn't necessarily "leap frog" over Honda's 1.5t civic, ... but it might step past it.
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  11. Carcus

    Carcus Well-Known Member

    A guess (using the 20% to 30% increase), ... maybe a 2019 Mazda 3 with a HCCI(ish) 2.0 engine could turn in EPA ratings of 32/45/38 ?
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  12. Jay

    Jay Well-Known Member

    Mazda's own press release today regarding Skyactive X says the engine will have a supercharger fitted:

    Of course, that could always change
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  13. wxman

    wxman Well-Known Member

    EPA Tier 2 Bin 5 NOx limit is 0.07 grams/mile. Euro 6 limit is 0.08 g/km or about 0.13 grams/mile.

    EPA Tier 3 regulations, which are currently being phased in, combines NOx and NMOG into a single emission category (NMOG+NOx). So the equivalent of T2B5 is T3B160.
  14. Jay

    Jay Well-Known Member

    I found this youtube video of a powerpoint presentation given by Mazda president and CEO, Masamichi Kogai and director and senior managing officer, Kiyoshi Fujiwara. The presentation outlines the direction and focus of Mazda's short, medium, and long-term plans, including Skyactive X technology. Fujiwara-san describes Skyactive X technology in detail beginning at about minute 25. The presentation is in Japanese with English subtitles:

    The Skyactive X presentation describes the advantages of gasoline controlled compression ignition vs spark ignition and the technical problems of achieving CCI. Some of the important takeaways:
    • Mazda solved the problem of achieving CCI over a wide range of rpm and load by using the spark plug to ignite a small area of fuel near the plug which acts as a piston to initiate CCI.
    • Spark ignition (SI) air-to-fuel ratio must be about 14.7:1 for the flame front to propagate. CCI air-to-fuel ratio is 36.8:1 (!)
    • Mazda claims CCI combustion over the full range of rpm and loads. The only time they resort to SI is cold temperature warm up. They claim the change in operation between SI and CCI is seamless.
    • Mazda uses a "highly responsive air supply unit" to send air into highly compressed cylinders. I can't tell from the illustration if it is a supercharger or turbocharger. The unit expands the range of CCI.
  15. Elixer

    Elixer Well-Known Member

    For those that want to better understand this technology, I found this explanation really useful:

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  16. Jay

    Jay Well-Known Member

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  17. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    I like the matte paint look. Wonderful things they do with wraps.
    Jay likes this.
  18. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Like Mazda and Honda diesel cars.
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  19. Jay

    Jay Well-Known Member

    yes. :(

    In June I finally made a decision to buy a new Honda Civic hatchback. Honda, for some reason, is trying their best to drive customers away from the 6MT and to the CVT. Their primary tactic is to not make enough 6MTs to satisfy demand. They make 6MT customers order one and then wait many months for delivery. I put my deposit down but insisted on a back-out clause if it doesn't arrive in 3 months. Oct is my due date and it doesn't look hopeful that my car will get here. I'm thinking seriously of opting out. I'm frustrated and angry at Honda for making me wait. I still like my current car, and this! I would definitely hold onto my current car for another year if there's a good chance Mazda comes through with Skyactiv x as promised. Go Mazda!
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  20. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Jay:

    The CX-5 with the SKYACTIV-D was supposed to arrive 4 different times over the past 6 years and we are still waiting.

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