Fuel Economy. Performance. Together.
Our philosophy is that if it's not worth driving, it's not worth building. So in our quest for better environmental performance, our goal was to reduce fuel consumption and emissions without compromising driving performance. To get there, we started with a clean sheet of paper and engineered every major component of the automobile to work together in efficient harmony. The result is something revolutionary.
THE SKYACTIV®-G 2.0L GASOLINE ENGINE The SKYACTIV®-G 2.0L Gasoline Engine
Currently, 95% of the world uses gasoline or diesel combustion engines, and by 2020 90% still will. In this fact we saw an enormous opportunity: If we could find a way to make the internal combustion engine work better, we could make a big difference in how much fuel the world uses and how much CO2 is emitted. Our solution is the SKYACTIV®-G gasoline engine, a 2.0-liter marvel that produces 10% to 15% more low/mid-range torque, along with 15% lower fuel consumption and emissions than our previous 2.0-liter engine.
What's the point of a high compression ratio? A bigger power stroke captures more of the expansion that happens when fuel is burned, meaning you harness a greater amount of energy from the fuel. Until now, high-compression engines faced a tough obstacle: knock, or premature ignition. Knock is an inefficient and potentially destructive combustion process where the heat and pressure in the combustion chamber cause the air/fuel mixture to ignite too soon.Combat knock: It's not a Clash album, it's the job of an array of innovations in the SKYACTIV®-G engine. These breakthroughs stave off excess temperatures in the chamber and speed up combustion to prevent knock, allowing the engine to achieve an astonishing 13:1 compression ratio on 87 octane gasoline. The Ferrari 458 reaches only 12.5:1 on premium. Rock on, Mazda.
4-2-1 exhaust system fights engine knock
Hot air: beloved by balloons and politicians, but an enemy of engine efficiency. Averting knock in a high-compression engine requires minimizing excess heat in the combustion chamber to avoid prematurely igniting the air/fuel mixture. So we developed a special 4-2-1 exhaust system with an extended pipe length that prevents the exhaust pulses from one cylinder from pushing hot exhaust gasses back into another.
To solve this, the exhaust is heated by slightly delaying the ignition timing. However, too much delay can cause unstable combustion. We came up with a novel solution: a cavity in the top of the piston that helps to stabilize combustion, even with delayed ignition.
The top of the piston is also dome-shaped. Not only does this make it look like a volcano, which is pretty cool, but it also helps to achieve high compression by reducing the volume of the combustion chamber.
Another method to improve knock resistance is to make combustion faster. Faster combustion means less time for the remaining air/fuel mixture to suffer those high temperatures, and that means less time for knock to rear its ugly head. The piston cavity also prevents the first milliseconds of flame from slowing itself down by hitting the top of the piston.
Advanced direct injection system stabilizes combustion
Another method to improve knock resistance is shortening the duration of the combustion. The faster the combustion, the shorter the amount of time the unburned air/fuel mixture is tossed around in those high temperatures. That means less time for knock to rear its ugly head.
With super-high fuel pressure of 2,900 psi, the SKYACTIV®-G six-hole injector improves vaporization and cooling of the air/fuel mixture, and mixes up the fuel more evenly.
It also provides much faster injection, allowing the fuel delivery to be split into multiple injection events. This helps to optimize the distribution of fuel in the chamber.
We were so obsessed with achieving optimal combustion that we studied air movement patterns inside the cylinder. Using that knowledge, the spray of fuel was adjusted to make the air in the chamber move in a tumbling pattern, helping spread the fire faster once combustion starts.
• Lighter pistons and piston pins (20% reduction)
• Lighter connecting rods (15% reduction)
• Reduced piston ring tensile force (37% reduction)
• Narrower crankshaft main journals (6% reduction in diameter, 8% reduction in width)
• Adoption of roller finger follower (greater than 50% reduction in valve friction)Adoption of compact electronic variable pressure oil pump (approx. 45% reduction in oil pumping loss)
The SKYACTIV®-DRIVE Six-Speed Automatic Transmission
Now that we had come up with such a revolutionary engine, we needed the ultimate transmission to get all that precious energy to the wheels. How do you build that? Study every modern transmission made, take the best features of each and fire up the blender. Then, top it all off by adding a brain, A.K.A. an advanced control module. The result is theSKYACTIV®-Drive six-speed automatic transmission. It shifts smoothly for steady acceleration and quickly for the connected feel of a manual transmission, while the brain delivers precision responsiveness and reliability.
• The fuel efficiency of a manual transmission
• Quick, direct shifting like a DCT
• Easy to control at low speeds like a conventional automatic
• Smooth, seamless shifting of a CVT
Torque converter and clutch together deliver smooth, direct feel
A conventional torque converter is still the smoothest, easiest way to control a car at slow speeds (like pulling in and out of your driveway or creeping through rush-hour traffic), but they're inefficient at higher speeds. Our solution: use the torque converter only below 5 mph, where it works best. The rest of the time SKYACTIV®-Drive uses a multi-plate clutch to directly and efficiently transmit power. That's called "lock-out," and we took it to an extreme level.
Because of the torque converter's more limited role, we were able to make it smaller, leaving room to package it with the clutch in the same space as a conventional torque converter.
A new mechatronic module combines the transmission control computer and all the sensors and shift solenoids into one unit. Think of it as the transmission's brain.
Each module is individually calibrated when the transmission is assembled so the computer can learn the precise response characteristics of each part it has to control.
Innovative design helps to improve fuel efficiency by 4% to 7%
As a result of this innovative approach to automatic transmission design, SKYACTIV®-Drive operates more efficiently than conventional transmissions. It upshifts smoothly and directly like its DCT competitors, it rev-matches precise downshifts, and it yields 4% to 7% gains in fuel economy.
The SKYACTIV®-BODY and SKYACTIV®-CHASSIS
With our SKYACTIV® Body and Chassis, we were determined to get more of that exhilarating Mazda driving feel while increasing crash safety performance and reducing weight. Through smarter engineering and materials, we were able to improve body rigidity by 30% (for better handling) and shed 220 pounds, all while improving crash safety performance. To give you more of that "oneness" between car and driver, the suspension was redesigned for greater agility at low speeds and more stability at high speeds.
It was time to get metal. In previous Mazda body structures, about 40% of the structure was comprised of high-strength and ultra-high-strength steel alloys. In the SKYACTIV®-Body, we increased that amount to 60%.
The body structure was made stronger and lighter through smarter geometry: By eliminating corners in each load path, we created a straight frame from front to rear. The back half of the center tunnel was also reinforced so load directed to the floor can be carried there as well.
Building a more efficient structure created manufacturing challenges. Some reinforced areas couldn't be accessed by conventional spot welders, so new techniques such as laser welding and advanced, structural adhesives-known as weld bonding-were used instead.
The rear suspension was rearranged to give it more toe-in, with the front of the tires angled slightly toward each other. That improves the stability, but normally at the expense of nimbleness.
No way we were going to give up nimbleness, so we used a quicker steering ratio and electric-power-steering tuning. That's good at low speeds, but on the expressway it can make the car feel nervous, like it drank too many energy drinks.
Geometry time again. In front, caster and trail were dramatically increased to the highest of any front-wheel-drive sedan; this gives the steering more self-centering, stabilizing force for enhanced feel and performance, especially at high speeds. Put simply, we made it Autobahn-ready.
In the rear, we raised the pivot point of the trailing arm by two inches to make bumps feel less bumpy and provide more stability when you hit the brakes.