For 2016 the Ford sourced 3.7 liter V6 gives way to Mazda’s new top engine in the CX9, a 2.5 liter direct-injected and turbocharged four cylinder engine. In the CX9 it is always paired with a six-speed automatic transmission in both front-wheel and all-wheel drive models.
While many turbocharged engines its size produce much more power, Mazda took a conservative approach here with a 227 horsepower base rating on regular unleaded fuel. If you spring for 93 octane premium, the engine can produce 250 horsepower.
In either case, the torque rating is 310 pound feet which is really where this engine is tuned to generate its grunt with minimal turbo lag. And to achieve this, they’ve incorporated a number of tricks with the design of the exhaust manifold and the turbocharger assembly.
It all starts with intake air that enters the filter box from above the grille and then travels back to the turbocharger located at the rear of the engine. From there it travels back up front to an air-to-air inter-cooler mounted ahead of the radiator.
It returns to the throttle body low at the front of the engine and into a composite intake manifold where it’s mixed with cooled exhaust recirculation or EGR, an assembly you can clearly see on top of the engine. By controlling this intake, the air-to-fuel ratio can be better managed.
Direct injectors and variable valve timing and a relatively high compression ratio of 10.5:1 handle the combustion cycle, but things get interesting at exit. The exhaust system has a variable valve body that enables the flow to be pinched off at lower rpm.
This narrower but faster exhaust flow keeps the turbocharger spinning quicker in the low ranges and reduces turbo lag to near zero. At higher rpm the valves open and allow full flow to allow turbo boost up to 17.4 PSI.
An computer controlled electronic servo as opposed to a vacuum operated one allows for better boost control across the RPM range. All of these technologies Mazda tells us contribute to a robust power curve down low and higher efficiency across the operating envelope.
For those who service their own, the major maintenance check points are all within easy view and reach. The coolant reservoir is up front and center, though it’s gray and not the white translucent color one usually looks for. Windshield washer fluid is off to the passenger side.
The air filter box is easy to reach but requires some wrestling to get into. The main fuse block and 12-volt battery are just behind that and the brake fluid in its expected place at the firewall ahead of the driver. Oil fill and dipstick are top and center of the engine together, best seen with the engine cover on.