See the DISI turbo engine in operation.
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This is Mazda's next-generation MZR 2.3L DISI* TURBO engine, designed to achieve harmony between two seemingly conflicting requirements: 'environmental-friendliness' including good fuel efficiency and clean emissions, and the 'high performance' necessary to realize true Zoom-Zoom driving.
*DISI: Direct Injection Spark Ignition
This engine combines a turbocharger with a relatively small displacement of 2.3 liters and a direct injection system. This arrangement simultaneously satisfies three requirements which were conventionally unobtainable: good fuel efficiency and clean emissions, overwhelming acceleration unique to turbocharged engines, and outstanding flat torque and excellent engine response equivalent to 3.5 - 4.0-liter V6 engines.
The combination of the direct injection system and turbocharger successfully turns the conventionally weak range of turbo engines into a selling point, creating new and different value for turbocharged engines.
- Clean emissions made possible by early activation of the catalyst
A direct injection engine injects atomized fuel directly into the cylinders, creating a very even air-fuel mixture around the spark plugs, which improves the engine's resistance to abnormal combustion (backfiring).
Therefore, the ignition timing can be safely delayed without risk of the engine backfiring, and the temperature of the exhaust gas can be rapidly increased. This hotter exhaust gas heats the catalyst to its thermal activation point very quickly after the engine starts.
Since the adoption of a lightweight single-scroll turbocharger substantially decreases the thermal capacity of the exhaust system, warm-up performance at start-up is further improved to achieve emissions that are cleaner than current regulations.
- Excellent fuel efficiency made possible by high compression
An in-cylinder cooling effect improves the engine's resistance to knocking so that a high compression ratio can be achieved without impairing low speed torque. This results in enhanced fuel efficiency. The MZR 2.3L DISI TURBO features a compression ratio of 9.5, which is the highest ratio for a high-output supercharged engine of this kind, and also achieves reduced fuel consumption.
- Smooth flat torque
The latent heat of vaporization generated when atomized fuel is injected into a cylinder under pressures of up to 11.5 MPa reduces the temperature in the combustion chamber (in-cylinder cooling effect) and thereby improves the air-fuel mixture charging efficiency. This increases torque by up to about 10 percent at around 3,000 rpm and generates 342 Nm, which is equivalent to 90 percent of maximum torque, over a wide range of engine speeds (2000 to 5500 rpm), realizing a smooth flat torque profile with a single-scroll turbo charger.
- High response over the full range
The in-cylinder cooling effect means that more fuel can be charged into the cylinder during initial acceleration. As a result, the turbocharger's turbine/compressor wind-up is fast and linear. Therefore, even with a single-scroll turbo, the engine receives the maximum benefit from the supercharging effect—even at engine speeds as low as 2,250 rpm—and enjoys excellent response over the full range. Mazda's turbo engine offers performance that matches the driver's intentions.
- Engine optimization in response to increased power
To withstand the increases in thermal load and combustion pressure caused by the power increase, the design and materials of each part are optimized. The rigidity of the cylinder block and head is improved by shape optimization. Block liners and head valve bridges are cross-drilled to improve their cooling characteristics. In addition, the crank shaft is made of steel and the crank pin diameter is increased. The connecting rod is also made of steel and its shape is optimized. Full floating wrist pins with an increased pin diameter are also used to improve the rigidity and strength of the rotating parts.
