Engines & Transmissions

Engines & Transmissions

Some of the biggest changes to the latest Mazda6 are found under the bonnet.

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With the new Mazda6 seeing the UK debut of Mazda’s cylinder deactivation SKYACTIV-G 2.5-litre petrol engine, and the popular SKYACTIV-D 2.2-litre diesel engine benefiting from a power upgrade to 184ps, some of the biggest changes to the latest Mazda6 are found under the bonnet.

On sale in the UK with a choice of five engines: 145ps and 165ps versions of the SKYACTIV-G 2.0-litre petrol engine, a 194ps SKYACTIV-G 2.5-litre petrol engine with cylinder deactivation, and both 150ps and 184ps variants of Mazda's SKYACTIV-D 2.2-litre diesel, the new Mazda6 offers a wide range of power units to suit all needs.

All engines are homologated according to the requirements of the new WLTP/RDE test cycle, and meet Euro 6d temp emissions regulations.

The 145ps SKYACTIV-G, plus both outputs of diesel engine come with a choice of six-speed manual or six-speed automatic transmissions, while the SKYACTIV-G 2.5 is exclusively matched to the six-speed automatic SKYACTIV-DRIVE gearbox. Equipped with Mazda's i-stop and i-ELOOP systems across all engines, the Mazda6 continues to deliver excellent efficiency.

Short for “Intelligent Energy Loop”, i-ELOOP is a pioneering system that stores recovered electricity in an advanced capacitor rather than employing a dedicated battery. The large-capacity electric double-layer capacitor (EDLC) captures and stores energy very quickly during the deceleration phase, which typically lasts only 10 seconds. Used to run the vehicle’s electrical systems, i-ELOOP can improve real-world fuel economy by up to 10% depending on driving conditions.

The i-stop idle-stop system uses combustion energy for restarting the engine, and only requires an electric-powered starter motor to provide a small degree of momentum during the initial restart phase.

With the growing importance of petrol in this segment, Mazda’s excellent ‘right-sized’ 2.0-litre engine offers an ideal balance of fuel efficiency and spirited driving thanks to powerful low- to mid-range torque. The updated engine’s intake ports have been redesigned, a new piston shape adopted, and the compression ratio raised to 13.0:1. The nozzle of the multi-hole injectors has been redesigned and fuel spray pressure increased. A coolant control valve makes warming the engine more efficient, and asymmetrical oil rings in conjunction with barrel-shaped piston skirts reduce mechanical friction.

These changes increase low-end torque by 6.2%, while also reducing real-world fuel consumption and particulate matter formation during combustion. The result is enhanced dynamic performance, fuel economy, and environmental friendliness. Emissions easily comply with new WLTP/RDE test cycles, falling well within the particle number limits without the need for a petrol particle filter.

The lower powered 1,998cc unit develops 145ps at 6,000rpm and maximum torque of 213Nm at 4,000rpm. It combines a combined fuel consumption of 45.6mpg and CO2 emissions of 141-142g/km. The higher powered unit of the same capacity develops 165ps at 6,000rpm and maximum torque of 213Nm at 4,000rpm. Its combined fuel consumption is 44.1mpg, while CO2 emissions are 146g/km.

Even better, with cylinder deactivation technology that shuts down two of the engine’s four cylinders in light load situations, the new 2.5-litre SKACTIV-G petrol is an excellent addition to the line-up. Running on two cylinders reduces pumping loss and mechanical resistance to improve efficiency. With a high 13.0:1 compression ratio, the reduced weight of an aluminum-alloy cylinder block, and a balancer unit that reduces low frequency rattling, the 2.5-litre engine achieves high levels of dynamic performance, fuel economy and quietness.

Adopting the same technology updates as the SKYACTIV-G 2.0, the new to the UK 2.5-litre unit develops 194ps at 6,000rpm and maximum torque of 258Nm at 4,000rpm. It has a combined fuel consumption of 42.2mpg and CO2 emissions of 153g/km.

Across the range of innovative SKYACTIV-G petrol engines a host of technologies ensure that the Mazda6 benefits from the very best powertrains. The shape of the intake ports has been carefully crafted to generate a stronger tumble flow during intake. Additionally, reducing the height of the piston crowns, while optimising their shape also strengthens tumble flow during the compression stroke and increases turbulence at the time of ignition. These factors cause the flame to spread faster from the spark plug and combustion is completed more quickly without knocking. The result is greater torque at low- to mid-range rpm and improved fuel economy at higher rpm.

The new Mazda6’s petrol engines also benefit from more efficient fuel injection, with the nozzles of the multi-hole fuel injectors redesigned and fuel pressure increased from 20MPa to 30MPa to realise a faster and more broadly dispersed spray. Fuel is thoroughly vaporised before it adheres to the walls of the cylinder to create efficient, waste-free combustion. Three-stage split fuel injection is used when the engine is cold and combustion is more likely to produce particulate matter. This improves vaporisation and atomisation of the fuel and reduces particulate matter formation by approximately 80 per cent. The result is excellent environmental performance that conforms to European particulate number regulations that came into effect in 2017.

Other internal changes include new asymmetrical oil rings that feature a larger outer radius at the top and a smaller radius at the bottom edge. This optimises the thickness of the oil film on the wall of the cylinder as the piston rises and falls, reducing mechanical resistance. In addition, revised piston skirt curvature realises an ideal barrel shape. The new skirts combine with the asymmetrical oil rings to significantly reduce mechanical resistance, contributing to better fuel economy.

A new variable displacement oil pumpsupplies the optimum amount of oil to the engine in relation to the engine speed and load at any given time. It uses a hydraulic sensor to monitor the engine for linear control of the solenoid valve to continuously change the amount of oil output by the pump. The supply of oil is therefore reduced at rpms where the engine does not require it, and this reduces mechanical resistance.

However, Mazda hasn’t ignored diesel when developing the new Mazda6. The award-winning and much praised SKYACTIV-D 2.2 is a clean diesel engine that delivers outstanding torque and dynamic performance, as well as excellent fuel economy.

New technologies aimed at reducing harmful emissions, realising a more robust driving experience, and delivering a quieter engine note have been incorporated into this established powerplant.

Now equipped with a urea Selective Catalytic Reduction (SCR) system that significantly reduces NOx emissions, the Mazda6 achieves an excellent level of environmental performance and complies with strict European emissions regulations (EURO6d-temp). The new SCR system operates continuously, reducing NOx emissions using diesel exhaust fluid like AdBlue; a urea solution injected into the exhaust stream which causes a chemical reaction that converts up to 90 per cent of the NOx in the exhaust into innocuous nitrogen and water. The system delivers outstanding environmental performance without sacrificing driving pleasure.

With its compression ratio raised from 14.0:1 to 14.4:1, the updated engine adopts Rapid Multi-stage Combustion, whereby high-pressure fuel injections (up to six) in quick succession generate a continuous burn with a shorter combustion period. This new combustion method results in quieter and more economical performance during low-speed, low-load city driving, but produces a linear engine sound that matches the degree of acceleration. It also takes Mazda one step closer to its goal of ideal combustion.

A new design for the egg-shaped pistons combines with ultra-high-response multi-hole piezo injectors to increase combustion efficiency. Sodium filled exhaust valves enhance heat transfer and coolant control valves improve engine warm-up efficiency to help achieve better real-world fuel economy.

Moreover, the new two-stage twin turbocharger with variable turbine geometry helps increase maximum output from 175ps to 184ps and maximum torque from 420Nm to 445Nm, resulting in even smoother and more powerful performance.It uses a smaller or larger turbine or both depending on engine speed. The larger turbine now adopts a variable geometry design that delivers boost more quickly at lower engine speeds. This increases boost efficiency throughout the engine’s operating range, increasing maximum power and torque for smoother and more powerful dynamic performance.

The precise control delivered by High-Precision DE Boost Control optimises boost pressure control and enables finer adjustment of fuel injection with the end result being an engine that responds instantly and precisely to accelerator pedal operation.

Added to the Mazda6 in its last update in 2016, Natural Sound Smoother and Natural Sound Frequency Control are both further evolved to deliver an even quieter cabin with a more pleasing engine note. The Natural Sound Smoother uses a dynamic damper in each piston pin to minimise piston vibration and reduce engine knock. Natural Sound Frequency Control modulates injection and combustion timing in 0.1ms increments, thereby overlapping the frequency valleys of combustion vibration with the peak frequencies of resonating parts to cancel out the vibration of each and further reduce knock.

The lower powered version of the engine develops 150ps at 4,500rpm and maximum torque of 380Nm from 1,800-2,600rpm. It combines a combined fuel consumption of 55.4-64.2mpg and CO2 emissions of 117-133g/km, depending on the choice of automatic or manual gearbox. The higher output unit of the same capacity develops 184ps at 4,000rpm and maximum torque of 445Nm at 2,000rpm. Its average fuel consumption is 55.4-60.1mpg, while CO2 emissions are 124-133g/km.

Like Mazda’s petrol engines, innovative technology ensures the diesel units are class-leading and across the new Mazda6 range whichever engine you choose you’ll benefit from the very best in SKYACTIV technology.