Mazda 6 Engine History / Design Features
Hi Guys and Girls,
I thought I would share an article with new Mazda 6 owners who are unaware of the history and design features of the entire engine range - 2.3 litre, 3.0 litre and diesel.
A new family of four-cylinder gasoline engines, next-generation common-rail diesel engines with breakthrough environmental capabilities and a new 3.0-liter, low-friction aluminum V-6 engine make the launch of the new Mazda 6 much more than a new midsize car platform.
It is the essence of Mazda 6's Zoom-Zoom - a new range of modern powertrains that exemplify Mazda's new spirit of leadership and innovation.
Mazda Motor Corporation's new family of 4-cylinder engines is the latest in a new range of powertrains that will establish Mazda as Ford Motor Company's center of excellence for all large I-4 gasoline engine development. The new engine will be used in a broad range of vehicles, beginning with the Mazda 6. It will be offered in three displacements: a 1.8-liter, 2.0-liter and an advanced 2.3-liter with Mazda's Sequential Valve Timing (S-VT), which improves performance efficiency, and balance shaft to eliminate vibrations resulting from free mass and momentum forces.
The new family of 4-cylinders provides Mazda with a common architecture the company can use for at least 200 future applications in the Ford Motor Company, including direct injection (DI) gasoline and the more extensive use of sequential valve timing.
But, this new gasoline engine technology is not the whole Mazda 6 powertrain story.
In select markets, Mazda 6 will introduce new Mazda-developed diesel engines with next-generation common-rail injection technology designed for environmental compatibility and outstanding torque responsiveness.
The Mazda 6 powertrain family will be available in some markets with a unique 3.0-liter V-6, also with S-VT and a new intake manifold.
"We've developed the Mazda 6 as a new, global, midsize car platform for the future," said Phil Martens, managing director product strategy, Design and Product Development. "And we've worked hard to give this platform the kind of modern powertrain technology that will do more than just compete in its segment - it will lead it."
The new powertrains offered in the Mazda 6 will be available with new computerized five-speed automatic transmissions or 5-speed manuals with gear ratios matched to the torque curves of each engine, delivering quick acceleration and quiet cruising.
High Technology 2.3-liter Engine
Among the key objectives for the new 2.3-liter engine was achieving more torque, horsepower and smoothness, while delivering improved fuel economy, lower emissions and minimal maintenance requirements. The new engine hits all of these marks, thanks to the use of lightweight aluminum, innovative engineering, such as the use of S-VT, balance shaft and a keen attention to detail.
Mazda's S-VT allows the point at which the engine's valves open and close and the duration they stay open to change with operating conditions, such as engine speed and air volume. Varying these parameters allows the engine to operate more efficiently at all engine speeds while maintaining drivability, improving power, fuel economy and emissions. Traditionally, camshafts open and close intake and exhaust valves at fixed points in the engine cycle, regardless of engine speed or air volume.
Located under the crankshaft, the balance shaft minimizes vibration by rotating at twice the speed of the crankshaft and offsetting the secondary inertia force of the rotating system. The balance shaft is fitted in its own housing and attached to the cylinder block for optimum positioning. It is driven by a gear to reduce drive losses.
Meanwhile, variable valve timing delivers more torque and more power than a conventional engine.
To achieve the aggressive targets on improving torque, horsepower and smoothness, Mazda engineers focused on several other areas, as well. First was developing a new intake manifold. Using an array of powerful computer aided engineering (CAE) tools to compare various designs and options, engineers developed a sophisticated new friction-welded nylon intake manifold with equal length runners that incorporate new devices called swirl control valves. Mazda engineers fitted these specially designed control valves into each of the intake runners, close to the cylinder head flange.
These valves or "tumble flaps" in the variable induction system are controlled by a solenoid actuator and are closed during light-load operations, such as idling at traffic lights, shifting actions and deceleration, to maximize combustion efficiency, fuel economy and emissions performance.
The valves are fully open during higher load conditions, roughly 5,000 rpm, to maximize volumetric efficiency and power output.
The intake manifold is constructed of part-recycled material. Its design improved engine sound quality by emphasizing the even-order engine harmonics - a key to the equal length design.
This innovative intake manifold design is further enhanced by the careful design of the air cleaner system. Mazda's air cleaner does more than simply clean the air. The system features a performance-tuned, bell-mounted, cold-air pickup duct at the very front of the vehicle, a large noise, vibration and harshness-tuned resonator in the wheel-arch and "organ pipes" designed to selectively feed back sporty sound to the driver under high throttle conditions.
To enhance fuel economy and reduce NOx emissions even further, Mazda engineers developed a water-cooled, electronically operated exhaust-gas recirculation (EGR) system. The EGR valve, actuated by a stepping motor, precisely redirects exhaust gas to the intake side of the engine, where it is inducted into the intake manifold through a short duct. The EGR passage is cast into the cylinder head.
To reduce engine back-pressure and to ensure quick catalyst warm-up efficiency with the 2.3-liter, Mazda uses a fabricated stainless steel exhaust manifold design of welded tubes. Unlike a conventional cast iron constructed exhaust manifold, the stainless steel exhaust manifold delivers low-heat retention in normal operation. A typical 4-cylinder exhaust manifold funnels into a single pipe and then into the catalyst.
In the Mazda design, a heat-insulating layer surrounds the portion where the four runners meet and a divider plate is located longitudinally in the exhaust pipe. This arrangement combines the heat retention benefits of a single pipe structure with the engine performance benefits of a dual-pipe structure. This concept of heat management allowed Mazda to simplify the rest of the exhaust system and eliminate the need for a close-coupled catalyst.
Eliminating the close-coupled catalyst and locating it under the floor, reduces engine back pressure, helping improve real-world performance and high speed fuel economy.
High quality stainless steel materials also were used for the extended service life of the muffler system, which has been tuned for a sporty sound quality under high-load driving conditions.
The engine and exhaust systems of all Mazda 6 variants - critical for keeping emissions low - are continuously monitored by a so-called onboard diagnostic system. The system uses a control lamp in the instrument cluster to warn the driver ("Check Engine") of a fault affecting a component relevant to pollutant emissions.
The 2.3-liter in the Mazda 6 also marks the appearance of a new engine management computer module. At its heart is a microprocessor, incorporating logic by Mazda. The system works through a CAN-bus to the chassis controls for intelligent vehicle dynamics features such as anti-lock braking and traction control. With the speed and capacity of this advanced computer chip, Mazda engineers were given the ability to fine tune the engine's performance with more extensive and sophisticated algorithms developed with the use of state-of-the-art, real-time simulation tools.
One of the side benefits of this new system is that some of the complexity of the control system required for optimal fuel economy and emissions could be simplified.
To simulate real world environments, Mazda engineers made extensive use of transient powertrain dynamometers that could be operated under extreme hot and cold conditions. These engine test facilities helped engineers simulate real world environments ranging from Artic cold to Saharan heat.
Mazda's engine development center in Hiroshima, played a leading role in this climate-controlled testing.
Lightweight Aluminum Construction
Mazda's 1.8-liter, 2.0-liter and 2.3-liter engines are made of a lightweight all-aluminum alloy construction that helps deliver superior performance and fuel economy.
Each 4-cylinder begins life as a precision gravity sand-cast cylinder block of high-grade aluminum alloy with cast-iron cylinder sleeves cast directly into the block. This closed-deck, deep-skirt cylinder block ensures a tight seal between the cylinder block and cylinder head. An aluminum alloy, ribbed ladder-frame structure, which carries the bottom bearing braces, mates to the cylinder block for optimized stiffness. But engineers didn't stop there. As the oil pan has a significant influence on joint rigidity between the cylinder block and transmission and can minimize vibration from the engine and transmission to the body, a ribbed aluminum oil pan was developed to complement stiffness properties and contribute to quiet operation.
Weight savings were obtained using a nodular cast iron crankshaft that requires only four counterweights for the 1.8-liter and 2.0-liter. The 2.3-liter engine has eight counterweights because of its larger displacement. Low friction-coated, lightweight alloy pistons with sinter-forged connecting rods for dimensional accuracy and fraction-split ends are used for a precision fit that enhances reliability and reduces noise and vibration.
Cylinder head construction is of aluminum-silicon alloy - thermally treated for strength and durability after the casting process - with an asymmetrical, four-valves-per-cylinder design. Two inlet valves (32.5-mm for the 1.8-liter; 35 mm for the 2.0-liter and 2.3-liter) are positioned at 19 degrees, and the two exhaust valves (28 mm and 30 mm, respectively) are positioned at 20 degrees. The compression ratio for the family of 4-cylinder engines varies from 9.7 to 10.8 depending on displacement and market.
The double overhead cams are driven by a hydraulically-tensioned silent chain drive, actuating the valves via mechanical tappets. Unlike previous-generation Mazda engines, the tappets are precision-fit during assembly and require no shimming. The intake and exhaust valves are nitrogen treated for durability.
Displacement variations for Mazda's new family of engines are achieved by increasing bore size (87.5 mm for the 2.0-liter versus 83.0 mm for the 1.8-liter) while keeping the common stroke length of 83.1 mm for the 2.0-liter and 1.8-liter. The stroke for the 2.3-liter with S-VT is 94 mm.
Smooth, Refined Operation
Mazda's use of S-VT and balance shaft in the 2.3-liter version of the company's new family of 4-cylinder engines provides the Mazda 6 an extra level of refinement and another level of NVH reduction.
The result is smooth, quiet operation even during spirited driving.
All 4-cylinder offerings in the Mazda 6 are mounted via a three-point torque-roll access management engine mount system. This Mazda mounting system supports the engine with two load-bearing mounts along its roll axis, one of which incorporates a hydraulic damping element to reduce powertrain shake on rough roads and reduce transmitted vibrations. A third bushed link - mounted from the transmission case to the subframe - provides rigid resistance to torque. Mazda's philosophy of separating the two primary forces on the engine mounting system leads to a reduction in powertrain vibration and harshness.
Clean-burn Innovation: Mazda EVVC
DIRECO-D's leap forward in combustion efficiency is a result of Mazda's new Expansive Vertical Vortex Combustion (EVVC) innovation.
EVVC takes full advantage of the high injection pressures of the second-generation injection system. It extends common-rail technology's benefits for lower emissions, better fuel economy, improved refinement and higher torque without needing to resort to the added expense of particulate traps.
"This Mazda breakthrough is a new approach to the combustion chamber in a diesel engine to create a highly efficient, even diesel combustion event," said Kenichiro Saruwatari, Mazda 6 powertrain engineering manager.
"The key is to diffuse the hot spot of the typical combustion to reduce tailpipe emissions."
The Mazda 6's DIRECO-D engines feature a uniquely shaped combustion chamber to achieve the EVVC combustion performance.
The head of the piston has a shallow, plate-shaped bowl which helps to shape the fuel-air mixture. Combined with the ultra-fine spray pattern of DIRECO-D's new fuel injectors, this design expands the vertical vortex inside the piston bowl.
The effect is better swirl and tumble of the fuel-air mixture, reducing the combustion hot spot that is responsible for higher NOx emissions in previous generation diesels.
Other refinement measures include:
Knock control for running on all fuel qualities between 87 and 99 octane.
Outstanding durability, sufficient to justify a 10-year, 240,000 km warranty (149,000 mile) and enable an oil change interval of 12,500 km (7,776 miles).
The rigidity of the engine block facilitates a stiff mounting of the transmission. This tremendously helps minimize vibrations induced into the body, even at maximum engine revs.
The crankshaft drive was designed with careful attention to reduce shaking forces.
The camshaft drive chain contributes to lower noise reflection compared to previous conventional roller chain designs.
The G-rotor oil pump, mounted in the engine block, is driven by a separate chain from the one that drives the camshafts.
The oil filter has an environmentally friendly design requiring only the internal element, not the entire assembly, be replaced at required oil changes.
Designed for Long Running Life and Low Maintenance
The design of Mazda's new 4-cylinder engines incorporates the latest measures for long service life and lower maintenance requirements:
The chain drive requires no maintenance over the life of the engine.
During scheduled maintenance, the valve lash no longer requires inspection. This has been accomplished through the reduction of actuating forces through weight optimization elements such as the valves and tappets; optimized cam contouring to avoid excessive contact forces, and the selection of optimal geometry and materials for moving parts and valve seat rings. Such attention to detail helps to bring down the lifetime maintenance cost for the owner.
Mazda 6 Pioneers Advanced Diesel Technology
The Mazda 6 pioneers a new diesel engine range that brings innovative, next-generation common-rail injection technology to the mid-size car segment.
Thanks to the insight of Mazda, European diesel customers can meet the stringent Euro Stage IV emissions standards, enjoy the exhilaration of 310 Nm (224 foot-pounds) of low-end torque, experience levels of refinement normally associated only with gasoline engines and drive nearly 950 kilometers (589 miles) per tank of fuel.
Two new variants of the Mazda DIRECO-D 2.0-liter diesel engine make their debut in Mazda 6, both characterized by robust, linear torque characteristics for spirited driveability:
A 136-PS / 100 kW (134 HP) version achieves peak torque output of 310 Nm (224 foot-pounds) at 2,000 rpm. Horsepower peaks at 3,500 rpm.
A 120-PS / 88 kW (118 HP) version with the same peak torque output but a steeper horsepower curve dropoff.
The new engine with aluminum four-valve per cylinder head generates extremely high pressure in its fuel system, achieves extremely precise control of its solenoid-actuated injectors and takes advantage of a special Mazda diesel-engineering innovation.
"This is an absolutely state-of-the-art diesel engine," Martens said. "It complements the contemporary design and new levels of refinement of the new Mazda 6, and it brings with it some very impressive Zoom-Zoom to extend the reputation of this new platform for great driving dynamics."
Environmental Advancements Take Top Priority
The new DIRECO-D common-rail diesel engine was created with environmental concerns as its top priority. It is symbolic of the impact that insightful engineering expertise can achieve in reducing the impact of the modern automobile on our environment.
The diesel-powered Mazda 6 makes it easy for customers to lessen their own environmental impact. Its Euro Stage IV designation and fuel economy also help customers qualify for various environmental tax incentives across Europe.
The new Mazda 6 diesel engines deliver the following environmental benefits over the current generation of diesels:
A significant reduction - 50 percent - in particulate emissions.
Reduced NOx emissions by 50 percent.
Next-generation Common-rail Injection
The Mazda 6 DIRECO-D engine family introduces new second-generation common-rail technology from Denso. Its fuel system pressure and technological sophistication eclipse the current level of available diesel engines.
High fuel pressure is at the heart of the benefits of common-rail injection. The new DIRECO-D engines feature maximum pressures of 1,800 bar (180 mPa; 2610 psi). This pressure is up to 33 percent higher than that of first-generation systems, many of which are in the 1,600-bar (160 mPa, 2320 psi) range.
"The higher the pressure that we can deliver to the injectors, the better we can fine-tune the combustion efficiency of the engine," Saruwatari explained.
A thick-walled tubular reservoir - the common rail - mounts on the engine to accumulate small quantities of pressurized fuel close to the injectors themselves. These sophisticated, micromanufactured injectors turn on and turn off the flow of pressurized fuel with a high degree of accuracy.
The new generation system uses this accuracy to full effect with multiple pilot injections and new post-injection capability. This cuts particulate emissions by nearly a third.
Pilot injections are small doses of fuel made prior to the main injection of fuel in each cylinder's firing. DIRECO-D is capable of multiple pilot injections, which help to smooth the sharp combustion character of the diesel engine to gasoline-like smoothness. Post injection is a similarly small dose of fuel injected after the main injection. It is in this area that DIRECO-D is exploiting common-rail technology's potential to lower particulate emissions. The small post injection is inserted with precise timing at the moment that is ideal for lower particulate discharge. "At peak horsepower output, this system is capable of up to 35,000 individual injections each minute, which is infinitesimal control," Martens said. "Achieving this level of precision unlocks the potential of the clean diesel engines of the future.
Adaptive Control for System Reliability
The DIRECO-D common-rail system features new adaptive control technology that helps to ensure the long-term reliability of the engine clean-burning properties.
This adaptive control is an ongoing checking process controlled by the engine control module. Using multiple injections, the module tests each injector regularly for its individual performance and then is able to adjust the fuel injection duration for each cylinder for optimal combustion levels.
This technology helps to compensate for minute variations in injector performance that can occur over time.
Added Refinement for Diesel Customers
Complementing the refinement inherent in the next-generation common-rail engines, DIRECO-D features several enhancements to provide the Mazda 6 customer outstanding levels of diesel engine smoothness, quietness and comfort.
The list is led by the dual-mass flywheel fitted to both DIRECO-D engine variants. The dual-mass flywheel compensates for the harmonic effect of diesel engine on the powertrain elements, eliminating the characteristic rattle often associated with diesels of the past.
Noise and vibration have been further reduced through the use of sophisticated fuel injection control with dual resonators that minimize intake resistance and intake noise, a urethane coating between the layers of the cylinder-head cover, and a sound-absorbing engine cover.
DIRECO-D Engine Features
The DIRECO-D engine architecture features a revised engine block and cylinder head engineered for the higher power and torque levels of the new common-rail configuration. Other key components, such as connecting rods and the crankshaft, have also been optimized for the higher output versions.
The engine also features a water-cooled EGR system and large, close-coupled exhaust catalyst as part of its multi-faceted approach to emissions robustness.
An IHI variable geometry turbocharger complements the engine's internal combustion-optimizing features by boosting charging efficiency. The engine's cam profiles are matched to the turbocharger's operating characteristics. The overall benefits are superior torque and low-end response with low overall emissions.
To minimize friction loss, DIRECO-D has a compression ratio of 18.3:1, the lowest it can be without affecting cold starting. The compact dimensions of Mazda's diesel provided engineers more freedom in the body and chassis design of the Mazda 6.
New 3.0-liter V-6
The new Mazda 6 also offers a higher performance gasoline engine, a 3.0-liter aluminum V-6, optimized for low-friction efficiency and high power and torque output. The 24-valve engine also is equipped with sequential valve timing.
Powered by the 222-PS / 163 kW (219 HP) V-6 with S-VT, the engine achieves its peak horsepower at 6,250 rpm. Torque output peaks at 273 Nm (202 foot-pounds) at 4,500 rpm.
"The new V-6 with sequential valve timing gives Mazda 6 uncompromised power and torque," Saruwatari said. "We believe it is the ideal complement to the refined, fun-to-drive nature of the Mazda 6 chassis."
For maximum fuel efficiency, the new V-6 incorporates friction-fighting features. Roller finger cam followers, with bucket-style tappets, minimize valvetrain friction that could negatively impact fuel efficiency.
The V-6 also takes advantage of the same air cleaner with variable duct and reduced back-pressure exhaust strategies as the four-cylinder engine range.
The aluminum cylinder block is manufactured with iron cylinder liners for durability. Four main-bearing caps and two longitudinal stiffening rails are combined in one girdle casting that is bolted to the cylinder block. This girdle has nodular iron-stiffening inserts surrounded by die-cast aluminum.
A structural cast-aluminum oil pan strengthens the bottom of the block and provides a rigid engine-to-transmission connection.
Cast aluminum alloy cylinder heads feature a pentroof-shaped combustion chamber that provides a 10.0:1 compression ratio. Intake valves are 33.5 mm in diameter and exhaust valves are 28 mm in diameter for excellent breathing properties.
The engine's forged steel crankshaft has nine fully machined counterweights. Connecting rods are sinter-forged for fracture-splitting. Pistons are a lightweight design with a graphite and molybdenum coating that minimizes piston skirt-to-cylinder-wall friction.
A single silent chain - with hydraulic tensioning - drives both camshafts in each cylinder bank. Each tubular steel camshaft is assembled with sintered high-carbon steel lobes.
The intake manifold is a two-piece composite-plastic design lower component that is integrated with the fuel delivery rail.
Twin-spray top-feed injectors are supplied by a returnless fuel system and triggered sequentially in synch with each cylinder's intake valve opening. The fuel pump is located in the fuel tank and computer controlled to deliver a robust range of pressures, depending on demand. A rear electronic module commands the pump and monitors fuel-rail temperature to guard against vaporization; if the fuel is warm enough to verge on vapor formation, output pressure is raised to maintain mass flow at the injectors.
A coil-on-plug ignition system eliminates secondary leads by positioning one coil triggered by the powertrain control module immediately above each spark plug.
New 5-speed Automatic and Manual Transmissions
Mazda 6 provides a choice of manual and automatic transmissions for each engine offering.
The transmission line-up has been optimised for Mazda 6's responsive driving character, refined character and ease of operation, engineered specifically for the higher torque outputs of the engines. The transmissions also excel in efficiency, durability and longevity.
"We've devoted a great amount of attention to shift quality using the Miata as a target," Saruwatari said. "The results are pleasantly matched to the driving dynamics of the new Mazda 6."
The manual transmission range includes:
? The Mazda G5M five-speed is designed to give the four-cylinder engine line-up crisp, short-throw shifting feel and low shifting effort in true sports car style. It features new dual synchronization - a high power synchronization feature for responsively quick shifting, easier shift effort and precision engagement - for the first and second gears.
? The A5M transmission is used for leveraging the higher-torque engines, including the V-6 gasoline engine and the diesel variants. This five-speed manual transmission also features Mazda attention to detail for optimal shift quality.
The automatic transmission range includes:
The FN four-speed automatic transmission is designed for use with the new 4-cylinder range, up to the 2.3-liter engine. The highly responsive, smooth shifting nature of the transmission has been optimized to match the engine's character.
Crisp, smooth gear changes for increased passing and merging performance - elements of Mazda's DNA - are achieved on the 4-speed automatic with the addition of a new oil pressure control module. Gear train receives a new heat treating technology, refined lubricant system and enhanced computer controls, enabling the transmission to handle Mazda's high powered 2.3-liter 4-cyl. without increasing the weight or size of the transaxle.
A JATCO 5-speed transaxle is fitted to V-6 equipped models. Its robust construction is ideal for the higher torque output of this engine. Smooth shifting quality for its specific application in Mazda 6 was a priority in its design configuration.
When other six-year-olds were playing with their tricycles, young Tadanobu Yamamoto was taking his first step toward becoming the lead chassis engineer who would create the driving dynamics of an all-new family of cars called the Mazda 6.
Yamamoto drove a car for the first time when he was six years old. Sitting next to his uncle on the front seat of a Mazda Karo, he was bitten early by the car bug on a quiet, rural lane in the Yokohama Prefecture of Japan where he grew up.
"I've always loved cars," said Yamamoto. "Maybe it was because the first car I drove was a Mazda."
When he grew up and became a professional engineer, Yamamoto was drawn to Mazda and its reputation for creating drivers' cars. Little did he know that he would someday create a car that would help to transform Mazda Motor Corporation in a new millennium.
Mazda 6's all-new platform was designed to compete with some of the best brands from Germany. It features a newly designed front and rear suspension that rewards the driver who wants dynamic performance, while at the same time delivering, comfortable, long-distance ride comfort.
Deep in its insightfully engineered core, the new Mazda 6 owes a small debt to the Zoom-Zoom of the Mazda Karo that was Yamamoto's first drive all those years ago.
Chassis development staff manager
Whether it is lifting weights, collecting Gundam models or developing a new range of powertrains for the Mazda 6, Kenichiro Saruwatari gives it his all.
Saruwatari loves his job as much as his hobbies.
Today, as assistant manager of powertrain development, Saruwatari points with pride to the Mazda 6's new range of powertrains.
"The new four-cylinder gasoline engine produces a pleasant sound by improving the resonance sound," Saruwatari said. "The new common-rail engine diesel engine is a highly efficient engine that minimizes emissions. And the sequential valve timing on our new 2.3-liter four-cylinder and 3-liter V-6 deliver fun-to-drive power."
Saruwatari takes a hands-on approach to his work.
"We conducted extensive drive tests to develop Mazda 6's performance and dynamic capabilities," Saruwatari said. "We worked to optimize the gear ratios to improve driving quality. We also worked on little things, like improving the movements of the pointers for the speedometer and tachometer to reflect this vehicle's upscale image."
In his spare time, Saruwatari enjoys skiing and collecting Gundam models, detailed, robotic action figures that are popular in Japan.
"I like Gundam models and I have an extensive collection of them."
Powertrain assistant manager
Source: Mazda Corp.