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MAZDAS SECRET CODE FOR INCREASING ZOOM-ZOOM: THE DISI TURBO
IRVINE, Calif., Aug. 31, 2006 Mazdas MZR 2.3-liter DISI (Direct Injection Spark Ignition) Turbo engine is Zoom-Zoom in its purest form. To energize the MAZDASPEED3, MAZDASPEED6 and the all-new CX-7 crossover SUV with ample power (263 hp at 5500 rpm in the MAZDASPEED3, 274-hp at 5500 rpm in the MAZDASPEED6 and 244 hp at 5000 rpm in the CX-7), Mazda engineers employed dual overhead cams, four valves per cylinder, turbocharging and intercooling. And as if this wasnt enough, they also developed one of the first direct fuel-injection systems available in the US market.
Squirting fuel directly into the combustion chamber is not a novel idea. All diesel engines use this type of fuel delivery, and piston-engined fighter aircraft began employing direct gasoline injection to ensure consistent performance when inverted flight was necessary during aerial combat. Direct injection came to motorsports in 1954, allowing competitors to eke out every last horsepower and mile-per-gallon for endurance racing its now considered an essential component in the design of competition engines.
In order to make an internal combustion engine run, liquid gasoline must first be converted to a vapor suitable for combustion. In most engines, fuel injectors operating at 40 or so psi spray atomized droplets into the intake manifold. But in the MZR 2.3 DISI Turbo, pressure is raised to 1,600 psi and the spray is directly into the cylinder. As a result, fuel droplets are significantly smaller. When exposed to air in the combustion chamber, these droplets instantly vaporize. That change of state (liquid to gas) absorbs heat from the surroundings.
Absorbing heat just before combustion is very beneficial to any engines health and well being. Cooling the intake charge raises its density, allowing more air to fit in a given space. More air yields more power. A cooler fuel and air mix is also less prone to detonation. That in turn facilitates a higher compression ratio and additional boost in turbocharged or supercharged engines. Relocated fuel delivery allows intake ports to be optimized for air flow instead of air and fuel delivery. The MZR 2.3 DISIs intake ports are positioned higher and run straighter with the injectors located downstream.
Injecting an atomized spray of fuel directly into the combustion chamber also causes a richer mixture to form around the spark plug, which prevents misfire. With less likelihood of misfire, the ignition timing can be delayed following a cold start to maximize exhaust gas temperature. Hotter exhaust delivered to the catalytic converter speeds its warm up. Bringing the catalyst up to light-off temperature as quickly as possible is the key to ultra-low exhaust emissions. Thanks to direct injection, the MZR 2.3 DISI Turbo engine clears the strictest global emissions regulations.
Squeezing the air-fuel mix harder with a high compression ratio pays off later in the four-stroke cycle. In most engines (including MZR 2.3 DISI), the compression ratio is identical to the expansion ratio. During the expansion phase, combustion energy is delivered to the crankshaft on its way to the wheels. With more compression theres more expansion and extra power from every increment of gasoline.
To recap, direct fuel injection enhances Zoom-Zoom several ways. It cools the intake charge and increases its density to build a bigger fire in the combustion chamber. Cool conditions also allow higher compression and extra turbo boost. In the case of Mazdas MZR 2.3 DISI Turbo engine, low- and mid-range torque is enhanced by 10-percent because of the 9.5:1 compression and expansion ratios. Beyond 2,500 rpm, 15.6 psi of boost does an excellent job of stuffing the combustion chamber and ripping the power curve.
Creating the DISI Turbo engine involved more than just changing the injection system and adding a turbocharger, though. The form and materials used for the major components are optimized to bear the added load and heat of the increased output. The aluminum cylinder block and cylinder head are made using a new implementation of the Mazda Advanced Precision Casting process, which increases their strength. In addition, cross drilling between the cylinder liners and between the valve bridges in the head improves coolant flow and heat resistance. The crankshaft and connecting rods are made of forged steel, wrist pins are a new full-floating design, connecting rods have an optimized shape and larger journal size, and pistons are designed for maximum stiffness and durability.
And there's more. Direct fuel injection, in combination with electronic throttle control, is the most precise way to regulate an engine's speed and load. With EPA combined fuel economy ratings over 20 mpg, the MAZDASPEED3, MAZDASPEED6 and CX-7 motor-on long after other high-performance rides stop to refuel.
MAZDAS SECRET CODE FOR INCREASING ZOOM-ZOOM: THE DISI TURBO
IRVINE, Calif., Aug. 31, 2006 Mazdas MZR 2.3-liter DISI (Direct Injection Spark Ignition) Turbo engine is Zoom-Zoom in its purest form. To energize the MAZDASPEED3, MAZDASPEED6 and the all-new CX-7 crossover SUV with ample power (263 hp at 5500 rpm in the MAZDASPEED3, 274-hp at 5500 rpm in the MAZDASPEED6 and 244 hp at 5000 rpm in the CX-7), Mazda engineers employed dual overhead cams, four valves per cylinder, turbocharging and intercooling. And as if this wasnt enough, they also developed one of the first direct fuel-injection systems available in the US market.
Squirting fuel directly into the combustion chamber is not a novel idea. All diesel engines use this type of fuel delivery, and piston-engined fighter aircraft began employing direct gasoline injection to ensure consistent performance when inverted flight was necessary during aerial combat. Direct injection came to motorsports in 1954, allowing competitors to eke out every last horsepower and mile-per-gallon for endurance racing its now considered an essential component in the design of competition engines.
In order to make an internal combustion engine run, liquid gasoline must first be converted to a vapor suitable for combustion. In most engines, fuel injectors operating at 40 or so psi spray atomized droplets into the intake manifold. But in the MZR 2.3 DISI Turbo, pressure is raised to 1,600 psi and the spray is directly into the cylinder. As a result, fuel droplets are significantly smaller. When exposed to air in the combustion chamber, these droplets instantly vaporize. That change of state (liquid to gas) absorbs heat from the surroundings.
Absorbing heat just before combustion is very beneficial to any engines health and well being. Cooling the intake charge raises its density, allowing more air to fit in a given space. More air yields more power. A cooler fuel and air mix is also less prone to detonation. That in turn facilitates a higher compression ratio and additional boost in turbocharged or supercharged engines. Relocated fuel delivery allows intake ports to be optimized for air flow instead of air and fuel delivery. The MZR 2.3 DISIs intake ports are positioned higher and run straighter with the injectors located downstream.
Injecting an atomized spray of fuel directly into the combustion chamber also causes a richer mixture to form around the spark plug, which prevents misfire. With less likelihood of misfire, the ignition timing can be delayed following a cold start to maximize exhaust gas temperature. Hotter exhaust delivered to the catalytic converter speeds its warm up. Bringing the catalyst up to light-off temperature as quickly as possible is the key to ultra-low exhaust emissions. Thanks to direct injection, the MZR 2.3 DISI Turbo engine clears the strictest global emissions regulations.
Squeezing the air-fuel mix harder with a high compression ratio pays off later in the four-stroke cycle. In most engines (including MZR 2.3 DISI), the compression ratio is identical to the expansion ratio. During the expansion phase, combustion energy is delivered to the crankshaft on its way to the wheels. With more compression theres more expansion and extra power from every increment of gasoline.
To recap, direct fuel injection enhances Zoom-Zoom several ways. It cools the intake charge and increases its density to build a bigger fire in the combustion chamber. Cool conditions also allow higher compression and extra turbo boost. In the case of Mazdas MZR 2.3 DISI Turbo engine, low- and mid-range torque is enhanced by 10-percent because of the 9.5:1 compression and expansion ratios. Beyond 2,500 rpm, 15.6 psi of boost does an excellent job of stuffing the combustion chamber and ripping the power curve.
Creating the DISI Turbo engine involved more than just changing the injection system and adding a turbocharger, though. The form and materials used for the major components are optimized to bear the added load and heat of the increased output. The aluminum cylinder block and cylinder head are made using a new implementation of the Mazda Advanced Precision Casting process, which increases their strength. In addition, cross drilling between the cylinder liners and between the valve bridges in the head improves coolant flow and heat resistance. The crankshaft and connecting rods are made of forged steel, wrist pins are a new full-floating design, connecting rods have an optimized shape and larger journal size, and pistons are designed for maximum stiffness and durability.
And there's more. Direct fuel injection, in combination with electronic throttle control, is the most precise way to regulate an engine's speed and load. With EPA combined fuel economy ratings over 20 mpg, the MAZDASPEED3, MAZDASPEED6 and CX-7 motor-on long after other high-performance rides stop to refuel.
