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2016 Mazda CX-9 shows 32% improvement in EPA-estimated fuel economy over predecessor; SKYACTIV-G 2.5 turbo

Mazda North American Operations released EPA-estimated fuel economy figures for its all-new 2016 Mazda CX-9. Certified at an EPA-estimated 22 mpg city/28 mpg highway/25 mpg combined, when equipped with front-wheel drive, the 2016 CX-9 achieves best-in-class (MY 2016 midsize, three-row, non-hybrid crossover SUVs for sale in the US) city and combined fuel economy ratings and class-leading highway fuel economy.

The second-generation CX-9’s efficiency reflect a 32% improvement compared to its predecessor. (In Canada, NR Canada estimates of fuel consumption put the improvement at 35%.)

CX9_004

Like Mazda’s entire lineup of 2016 cars and crossovers, the 2016 CX-9 has adopted efficient, lightweight SKYACTIV Technology. Similar to the 2016 MX-5 Miata with its 29% improvement in EPA-estimated fuel economy versus its predecessor, the CX-9 benefits from a significant weight reduction, yet it adds amenities and provides more agile handling dynamics and improved performance.

At the heart of the 2016 CX-9 is its new SKYACTIV-G 2.5T engine, which produces the power of a V-6 engine without the fuel-efficiency penalty. SKYACTIV-G 2.5T is the first turbocharged engine in the SKYACTIV-G series.

CX-9’s engine delivers 310 lb-ft (420 N·m) of torque—comparable with a naturally aspirated 4-liter gasoline engine—from just 2,000 rpm and 250 hp (186 kW) at 5,000 rpm using 93-octane gasoline (227 hp with 87-octane). It comes paired with a six-speed SKYACTIV-Drive automatic transmission.

Traditionally, turbocharged engines have suffered from poor dynamic performance at low rpm, including turbo lag, and disappointing real-world fuel economy. SKYACTIV-G 2.5T overcomes these problems with the Dynamic Pressure Turbo, the first turbocharging system that can vary the degree of exhaust pulsation depending on engine speed, and a cooled exhaust gas recirculation (EGR) system that allows the engine to maintain the ideal air-fuel ratio (λ=1) over a wider output range.

Features of SKYACTIV-G 2.5T include:

  • High compression ratio. Mazda engineers achieved a compression ratio 10.5:1, one of the highest for any turbocharged engine with an 89-mm bore size that can run on regular gasoline.

  • Dynamic Pressure Turbo. SKYACTIV-G 2.5T is the first turbocharged engine with the ability to change the degree of exhaust pulsation depending on engine speed. At low rpm (below 1620 rpm), the volume of the exhaust ports is reduced by closing a series of valves located just before the turbine that drives the turbocharger. This reduces interference between exhaust pulses and maximizes the energy of each pulse to obtain a high turbine driving force.

    At higher rpm, there is sufficient energy in the exhaust flow and the valves open, allowing the turbine to be driven by a steady flow of exhaust gases as in a traditional turbocharger. Whereas existing variable turbochargers adjust the speed or direction of exhaust gas flowing into the turbine, Dynamic Pressure Turbo is a unique technology that varies the degree of exhaust pulsation.

    Further assisting CX-9 to maximize turbocharger efficiency is a 4-3-1 exhaust. With this setup, the exhaust from the middle two cylinders (2 and 3) is joined into a single port, while the exhausts from the outer cylinders (1 and 4) each have their own ports. These three ports come together at the entrance to the turbocharger’s exhaust side, where there is always one exhaust pulse arriving every 180 degrees of crankshaft rotation. Not only does this very compact manifold keeps the exhaust pulses separate for maximum energy extraction, it also harnesses each exhaust pulse to suck the residual exhaust from the adjacent ports.

  • Cooled Exhaust Gas Recirculation (EGR). This system takes some of the inert exhaust gas that results from the combustion process and reduces its temperature by passing it through a cooler before introducing it back into the engine’s air intake. This lowers the temperature of combustion in the engine from approximately 500 ˚C (932 ˚F) to just over 100 ˚C (212 ˚F), preventing knocking, expanding the range in which the engine can maintain the ideal air-fuel ratio and reducing the need to retard ignition timing.

  • SKYACTIV-G principals of efficient combustion. SKYACTIV-G 2.5T is based on the naturally aspirated SKYACTIV-G 2.5 and features the same bore, stroke and bore pitch. Parts of the fuel system, such as the fuel pump and fuel injection system are also shared, helping SKYACTIV-G 2.5T to achieve the efficient combustion for which SKYACTIV-G engines are known.

Front-wheel drive is standard, and Mazda’s predictive i-ACTIV all-wheel drive is optionally available. i-ACTIV all-wheel drive sends power where it’s needed before the driver can sense a loss in traction by measuring road and vehicle conditions more than 200 times per second via 27 sensors.

Due to its lightweight design, i-ACTIV all-wheel drive adds little mechanical friction.

The 2016 Mazda CX-9 will go on sale in late spring 2016. Final packaging and pricing will be announced closer to its on-sale date.

Comments

mahonj

A 32% improvement is very impressive - it is what you would expect from Hybridisation.

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