Vision67 said:
Wll the turbo engine on this car produce full power independent of altitude, i.e. the boost increases to compensate for altitude, or is max boost a constant, i.e. power drops as a function of altitude.
I live in Colorado at 6700 feet and most places I want to go re uphill. If it maintains power with altitude, it's a good fit. (thumb)
I found some info about this engine, but I still cannot find a technical explanation of the turbo boost control system.
MZR 2.3L DISI Turbo Engine
In addition to delivering a high-performance Zoom-Zoom driving experience, the MZR 2.3L DISI Turbo engine also exhibits good environmental compatibility with low fuel consumption and Euro Stage IV emissions. This powerplant is a direct-injection turbocharged unit developed by Mazda to achieve three aspects of performance that are difficult to realize with conventional manifold injection engines: good fuel-economy and low exhaust gas emissions, powerful acceleration thanks to the turbocharger, and a full and flat torque curve throughout the rev range for exceptional engine response.
Mazdas MZR 2.3L DISI Turbo injects fuel into the cylinders at pressures as high as 11.5 MPa, which cools the combustion chambers (internal cooling effect) through latent heat of vaporization, thereby improving the charging efficiency. This can increase torque by up to 10 percent at around 3,000 rpm compared to a conventional manifold injection type turbo engine, making powerful, easy-to-control torque available across a wide range of engine speeds. This high power flat torque curve is attained by the use of a fixed geometry turbocharger.
The internal cooling effect within the combustion chamber increases the cylinder charge volume under initial acceleration and hence the exhaust-gas flow, causing a linear increase in rotation speed of the turbocharger's compressor wheel. As a result, the turbocharger provides boost effect soon after the accelerator is pressed at around 2,500 rpm assuring excellent response at low to mid-engine speeds.
High-pressure direct injection of fuel into the cylinder also results in an optimized air-fuel mixture forming in the vicinity of the spark plug, reducing the risk of misfire. This allows earlier ignition, making it easy to raise the temperature of the exhaust gas. Moreover, use of a lightweight, fixed geometry turbocharger dramatically reduces the thermal capacity of the exhaust system, minimizing the loss in temperature of exhaust gas. As a result, the catalytic converter reaches its activation temperature faster after the engine is started. These advantages enable Mazda3 MPS to meet Euro Stage IV emissions regulations.
Because the internal cooling effect within the combustion chamber reduces knocking tendencies and boosts fuel economy without sacrificing low-end torque, the MZR 2.3L DISI Turbo engine has a relatively high compression ratio for a turbo engine of 9.5:1 which contributes to improved fuel economy.
The form and materials used for the respective engine components are optimized to bear the added load and heat of the increased output. The cylinder block and cylinder head are optimally shaped to increase their strength. In addition, cross drilling between the block liners and between the valve bridges on the cylinder head improves cooling performance. All moving parts have been made stronger and more rigid. The crankshaft is made of steel, and the diameter of the crank pins is increased. Connecting rods are also made of steel, and the shape of the rods is optimized. Full-floating pistons are used with increased-diameter pins. The shape of the radiator fan blades has also been optimized, the capacity of the electric fan motor increased and a flap function added to the fan shroud controls the adequate airflow to the radiator. These measures greatly improve the radiator's cooling performance at all engine speeds.
