Mazdas Holy Grail Of Gasoline Engines Is Completely Fascinating. Mazdas hotly anticipated SKYACTIV X Spark Controlled Compression Ignition engine has been described as the Holy Grail of gasoline motorssomething with diesel like fuel economy, but far better efficiency. I went to Germany to talk to Mazdas extremely nerdy engineers, and before I actually drove the thing, heres what I learned. Full Disclosure Mazda wanted me to drive their SKYACTIV X prototype, so the company flew me to Frankfurt, Germany, put a nice roof over my head, and fed me delicious foods whose names had more umlauts and Scharfes Ss than I could count. Mazda brought executive officers, VPs and managers from its powertrain, vehicle development, and research and development teams to explain to journalists how the SKYACTIV X Spark Controlled Compression Ignition engine works, and why it matters. In addition, Mazda discussed its all new platform, which is where well start before jumping into the exciting SPCCI engine goodness. The New Platform. Despite having driven some prototype next generation Mazda. Frankfurt, I cant really say much about its improvement over the outgoing bones. Research used 2000 Mazda values for all models. Motor Trend reviews the 2000 Toyota 4Runner where consumers can find detailed information on specs, fuel economy, transmission and safety. Find local 2000 Toyota. But the main points executive manager of vehicle development Hiroyuki Matsumoto stressed when talking about the new structure dealt with refinement. Matsumoto said that, in its effort to improve a driving feeling they call Jinba Ittai Connection between horse and rider, the company studied the human gait to establish a platform that optimizes human ability to balance. Part of that involved designing the seat supports to maintain natural S curve of the spinal column by the erection of the drivers pelvis you can see that below. Mazda also designed a new seat structure thats apparently able to quickly and smoothly transmit the energy input from vehicle body to the drivers pelvis. On top of that, Matsumoto told journalists that the body has been stiffened to reduce the transient response time between the input load on one damper, and the response load at the damper in the opposite corner. Mazda does this by using what it calls ring structures shown in the dotted green circles below The engineer also mentioned suspension and tire changes aimed at smoothly controlling energy transfer from the wheel to the body, as well as NVH changes like the 1. Ultimately, Mazdas main points when discussing the new platform seemed to revolve around driver comfort, with emphasis on ride quality, noise, and the way the car communicates inputs to the drivers ass. Unfortunately, I didnt spend enough time in the prototype to really assess how much better this platform is than the last. Well have to wait for a long term test for that. Leave it to a tiny car company like Mazda to pull off something the big players have been trying to figure out for years. Thats the deal with the new SkyActivX. The Benefits Of Compression Ignition. To understand the whole point behind Mazdas new gasoline compression engine tech, lets look at the seven factors the company works on to increase internal combustion engine efficiency shown on the left of the graphic below. They are compression ratio, specific heat ratio, combustion period, combustion timing, heat transfer to the wall, differential pressure between intake and exhaust, and mechanical friction. Improving these attributes theoretically leads towards the ideal internal combustion engine, and SKYACTIV X takes a number of steps in the right direction. Higher Compression Ratio And Specific Heat Ratio. Mazda mentions in its presentation that combustion engine efficiency is related to compression ratio and the intake charges specific heat ratio via the equation above. In other words, cranking up compression ratio and specific heat ratios yields better efficiency. SKYACTIV G, Mazdas current generation of gasoline engine technology, used a clever exhaust system, a piston cavity, and a high pressure fuel system with multi hole injectors to prevent knocking and to allow for a ridiculously high 1. SKYACTIV X, a compression ignition engine, cranks that figure up to between 1. As for bumping up that specific heat ratio k value, Mazda says running the engine lean and decreasing its combustion temperature takes care of that. We know that k for air is about 1. That means the more air you can put into that air fuel charge, the higher that overall k value, and thus the greater the efficiency. Decreased combustion temperatures are a result of lean burn and indeed, why NOx emissions are so low for this type of engine. The benefit, Mazda shows in the plot above, is that the lower combustion temperatures mean less energy is lost to molecular vibrations and decomposition. Thus, a lower combustion temperature yields a higher k, whichagainmeans better efficiency.
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