Is the internal combustion engine dead? The number of firms around the globe sinking capital into advancing electric drive technologies, battery chemistry, and other alternative propulsion systems might suggest the internal combustion engine has finally reached its swansong, but Mazda begs to differ. Although the Japanese automaker has tinkered with a number of advanced propulsion systems over the past decade, it feels there's plenty of life left in conventional, fuel-burning engines, albeit not without a little help from new technologies.
The company's wide-reaching SkyActiv program promises to refine engines and transmissions alike in the pursuit of improved fuel economy and reduced emissions, but the company has another (and arguably simpler) card up its sleeve: the i-Stop start/stop system. Although i-Stop isn't offered in North America, we recently had a chance to sample a Japanese-spec Mazda3 so equipped.
Look Ma, No Belt Alternator Starter
In this day and age, a start/stop system isn't exactly revolutionary technology, but i-Stop is a relatively new addition to Mazda's powertrain portfolio. The system was first introduced in Japanese-market Mazda3 and Biante minivans in late 2008, before being rolled out into models destined for European and Australian markets. Mazda's system does, however, break from most other start/stop systems in one notable way: while most use a belt-driven starter/alternator to restart the engine, i-Stop accomplishes this same feat via direct fuel injection.
Mazda's i-Stop system is fitted to the company's 151-horsepower, direct-injection 2.0-liter I-4. When a driver brings the vehicle to a stop, the engine computer analyzes a number of different factors (manual transmission cars, for instance, need to be shifted into neutral). Once it determines that the vehicle has come to a halt, the computer manipulates both the throttle and alternator to shut off the engine, and then aligns each piston at the center of its stroke. When it's time to restart the engine, fuel is injected into a single cylinder and ignited, allowing the crankshaft to begin revolving before the starter motor completes the process.