2013 Mazda CX-5 and the 2.0L SKYACTIV-G

Discussion in 'In the News' started by xcel, May 8, 2012.

  1. xcel

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

    [​IMG]The problem, low internal combustion efficiency. The solution, Mazda’s SKYACTIV.

    [fimg=right]http://www.cleanmpg.com/photos/data/501/SKYACTIV_Badge.jpg[/fimg]Wayne Gerdes - CleanMPG - May 8, 2012

    SKYATIV - It is more than just a slogan or badge. It stands for fuel efficiency.

    Mazda’s range of SKYACTIV technologies are designed to improve the efficiency and sustainability of the company’s latest and future generation of vehicles.

    Mazda’s trademarked SKYACTIV moniker is not some “pie-in-the-sky” elixir guaranteed to solve all the world’s problems but it does one thing better than any other OEM internal combustion engine and that is provide greater fuel economy at lower cost through optimized internal combustion engineering.

    SKYACTIV-G 2.0L Gasoline Engine

    Mazda has advanced the state of the internal combustion engine to an art form thanks to a range of entirely new technologies in order to produce its highly-efficient direct injected SKYACTIV-G 2.0L gasoline engine. The engine takes the compression ratio to an entirely new level while solving most of the issues that has hindered high compression engines from providing normal drivability until now.

    SKYACTIV-G 2.0L Highlights
    • Exceptionally high 13:1 compression ratio in North America (14:1 in other markets due to a higher fuel octane).

    • Extraordinary compression ratio made possible thanks to a 4-2-1 exhaust system, redesigned piston cavity, new multi-port injectors as well as other innovations to avoid abnormal combustion (knocking).

    • Continuously variable sequential valve timing (dual S-VT) on the intake and exhaust minimizes pumping losses.

    • Internal engine friction was reduced by 30 percent.

    • Overall weight was reduced by 10 percent.

    • Approximately 15 percent lower fuel consumption and 15 percent more torque at lower and mid-range RPMs than the previous Mazda 2.0L.
    120 years of non-stop development on the internal combustion engine has yet to overcome the waste of 60 to 90 percent of the energy contained in the fuel that keeps it running. Since this energy loss is primarily thermal and can be attributed to the exhaust, cooling system, and engine and transmission surfaces, Mazda’s R&D focused on improving the engine’s thermal efficiency and reducing internal engine friction.

    The six controllable factors at the heart of this approach are:
    • Compression ratio
    • Air-to-fuel ratio
    • Combustion duration
    • Combustion timing
    • Pumping losses
    • Mechanical friction loss
    The goal was to optimize each of these factors to create the current best available internal combustion engine. Ultimately, the compression ratio would end up playing a central role among these factors in both gasoline and diesel engines.

    Higher Compression Ratios Rather Than Downsizing

    Most automakers are looking to improve the average fuel economy of their internal combustion engines by reducing displacement and offset the loss of power and torque with turbochargers or superchargers.

    Although this is an effective approach, Mazda has chosen a different approach, namely to optimize and raise the compression ratio.

    By rethinking common thermodynamic principles, Mazda engineers have succeeded in building an engine with an extraordinarily high 13:1 compression ratio that can run on regular 87 Octane gasoline. This is a level only seen thus far in non-diesel high-performance race car engines on high octane racing fuels and most certainly not intended for everyday use.

    While raising the compression ratio in a gasoline engine increases its thermal efficiency and its fuel economy, high compression in conventional engines leads to unwanted abnormal combustion known as knocking and the associated reduction in torque. A richer mixture and delayed ignition timing are used to avoid knocking, but these also come at the expense of fuel economy and torque. So how was this issue overcome?

    Ingenious Thinkers

    Knocking takes place when the fuel-air mixture ignites prematurely because the temperature and pressure are high enough within the cylinder to self ignite mixture before it was intended by the spark plug. This can be countered by reducing the quantity and pressure of hot residual gases in the combustion chamber.

    Exhaust Manifold - In response, Mazda developed a special 4-2-1 exhaust manifold, which, due to its relatively long runner structure, prevents the exhaust gas that has just moved out of the cylinder from being forced back into the combustion chamber. The resulting reduction in compression temperature inhibits knocking.

    Combustion Duration was also reduced. Faster combustion shortens the time the unburned fuel-air mixture is exposed to high temperatures, which enables normal combustion to conclude before knocking occurs.

    Special piston crowns and injectors - The new engine also received special piston cavities, which allow the initial combustion flames to propagate without interference, and new multi-hole injectors, which enhance fuel spray characteristics. Together with the 4-2-1 exhaust manifold, these innovations resulted in a substantial 15 percent increase in torque and fuel economy over Mazda’s older 2.0L gasoline engine.

    Reduced Pumping Losses - To improve engine efficiency, it is also necessary to reduce the pumping losses that occurs at lower engine loads when the piston draws in air through a tight restriction called the throttle plate while moving downward during the intake stroke.

    The amount of air going inside the cylinder is controlled by the throttle plate located upstream of the intake pipe. At lower engine loads, only a small amount of air is necessary. The throttle is nearly closed, causing a vacuum inside the intake. As a result, the piston has to overcome a strong vacuum through a process known as pumping loss, which negatively affects efficiency.

    Mazda managed to minimize pumping loss with a continuously variable dual S-VT (sequential valve timing) on the intake and exhaust valves. This changes the opening and closing timing of the valves, enabling the air intake quantity to be controlled by the valves rather than the throttle.

    During the intake stroke, the throttle and intake valves are kept wide open while the cylinder moves downward. The intake stroke finishes when the piston reaches the cylinder bottom (bottom dead center or BDC). But if the intake valves close here, there is too much air inside the cylinder when only a small amount of air is needed at lower engine loads. In order to push out the excess air, the intake S-VT keeps the intake valves open when the piston starts to move upward during the compression stroke. The intake valves then close when all unnecessary air is pushed out.

    This is how an S-VT minimizes pumping loss, making the overall combustion process more efficient.

    A drawback to this process is destabilized combustion. Since the intake valves are kept open even when the compression stroke starts, the pressure inside the cylinder decreases, making it difficult for the fuel-air mixture to combust. Thanks to the relatively high 13:1 compression ratio, combustion chamber temperatures and pressures are somewhat elevated at the point of optimal ignition combustion so the combustion process remains stable despite reduced pumping losses.

    2013 Mazda CX-5 and the 2.0L SKYACTIV-G

    [​IMG]
    The technoolgy's inside.​

    What good is the engine if it drives a cacophony of gear parts in the transmission?

    Mazda came up with a redeveloped, high-precision six-speed manual transmission. With a remarkably compact and lightweight design along with diminished internal friction resistance, the SKYACTIV program has provided another multiplier to reduced fuel consumption and emissions.

    SKYACTIV-MT – The ultimate six-speed manual transmission

    Mazda built the innovative new SKYACTIV-MT six-speed manual transmission to improve fuel economy by lowering its weight, making it smaller and more efficient without compromising drivability. Mazda benchmarked the Miata which incorporates one of the slickest shifting manuals ever to be installed in an automobile.

    The SKYACTIV-MT was optimized for front-engine, front-wheel-drive vehicles with easy yet precise shifting patterns. It was also re-engineered with a considerably smaller and lighter design and provides better fuel economy thanks to reduced internal friction.

    The Result

    As posted above, other manufacturers are using advanced direct injection while others still are using direct injection and turbo charging with downsizing to achieve acceptable performance and the highest high fuel economy.

    As of this writing however, none of those approaches comes close to providing the efficiency that Mazda’s SKYACTIV technology placed within the 2013 Mazda CX-5 compact Crossover can. That is its 35 mpgUS highway rating when equipped with the 6-speed manual transmission. We have featured the 155 HP SKYACTIV as far back as the 2011 NYIAS and highlighted it as a hidden gem at both the Detroit and Chicago Auto Shows earlier this year. Now it’s time to put up or shut up.

    2013 Mazda CX-5 and the 2.0L SKYACTIV-G

    [​IMG]
    $21,490 including D&H as she sits in the drive. What is that tree growing out of it all about ;)

    [​IMG]
    70.4 mpg on its first drive over 8.4 miles. I do not believe any other compact crossover can do that?​

    Now that we are finally driving one, “put up” indeed! Not bad Mazda, not bad at all.
     
    Last edited by a moderator: Aug 20, 2012
  2. Harold

    Harold Well-Known Member

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    That is really good for a all wheel drive! If it is AWD? H
     
  3. herm

    herm Well-Known Member

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    If you get a chance test premium gasoline in the CX-5.
     
  4. xcel

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

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    Hi Harold:

    The 2013 Mazda CX-5 with the stick cannot be purchased as an AWD. See the 2013 Mazda CX-5 Specifications write-up for more.

    Along similar lines, there is a transmission hump running through the back seat area of this FWD variant.

    Herm, not a chance as I will top it off tomorrow or Wednesday for its aFCD offset Fuel Economy loop depending on the weather. It is already full with whatever STI filled it with when it arrived this morning. I suspect I will be able to add another 3 or 4 gallons to top off and that mix will not provide what could be a more fuel efficient setup. The European’s and Asians get the 14.0:1 2.0L anyway, not us :(

    Wayne
     
  5. WriConsult

    WriConsult Super Moderator

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    I'm pretty sure the one Wayne is driving is FWD.
     
  6. Carcus

    Carcus Well-Known Member

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    2,000 lb towing capacity and 8.5 inches of ground clearance ....nice.

    /this could dig into Subaru's market
     
  7. herm

    herm Well-Known Member

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    It still has a very high compression ratio, unique in the market... it would be an interesting experiment.
     
  8. Carcus

    Carcus Well-Known Member

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    Wayne,

    Are you driving the 6MT? Can we look forward to some SS numbers?

    /I wonder how all this new tech will hold up over time with e10/e15? Seems to me if you let the car sit for a while and get some water entrapment or varnishing then you could have trouble with all the precision mixology, high compression, and computer control going on (vs a more rudimentary system) .... but I dunno, maybe it actually works the other way -- advanced engine tech = better able to handle ethanol difficulties(?).
     
  9. xcel

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

    Hi Carcus:

    Local forecast is showing mid 50's with light winds by noon so the fuel economy drive calibration should be completed later today. Steady States come afterwards of course.

    Regarding E10, the new engines are designed to handle it far better than anything from the past and they are only getting better. From my understanding of how Mazda did it, it was that exhaust manifold design to reduce pressure for the most recently opening exhaust valve to eject hot exhaust gases and the very unique piston crown that made the 13.0:1 compression ratio possible.

    [​IMG]

    This SKYATIV-G piston does not sport your ordinary everyday piston crown.

    I also hope we will see the 1.3L SKYACTIV-G with a modern day 6-speed MT in the 2 soon as well. A 5-speed MT and a CVT are being offered in the Demio (the 2 here) in Japan right now.

    Wayne
     
    Last edited by a moderator: Aug 20, 2012
  10. Carcus

    Carcus Well-Known Member

    Nope .... somewhat domed and complicated. Looks like it could be susceptible to carbon buildup (?)-- but I guess the computers will handle any pre-ignition problems.

    Looking forward to seeing your results.

    /add, looks like Mazda is on to something here, ... I'm just a constant skeptic.
     
    Last edited by a moderator: Aug 20, 2012
  11. brick

    brick Answers to "that guy."

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    I would be pretty surprised if carbon buildup were an issue. You need rich combustion somewhere in the cylinder for that to happen, and with this kind of precision that seems awfully unlikely. Even if the computers were wrong, Mazda certainly ran this design to death in a dyno cell as verification.
     
  12. 50 mpg by 2012

    50 mpg by 2012 Well-Known Member

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    Our local dealer seems to sell any extra CX5s within 4 days of hitting their lot.
     
  13. xcel

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

    Re: 2013 Mazda CX-5 and the 2.0L SKYATIV-G

    Hi 50 mpg by 2012:

    They are indeed a "hot" item. Good Fuel Economy, nice size and decent pricing. I have posted a few stories on their production output capability being ramped up to try and keep up with demand.

    Wayne
     

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