Gasoline direct injection and turbocharging are modern technologies that promise maximum performance. Bosch has intelligently combined both technologies to give gasoline engines torque and economy at all revolution speeds

If common-rail diesel injection technology is showing great promise, petrol heads need not lose their calm. Bosch, which pioneered common-rail diesel injection technology has combined turbo- charging with gasoline direct injection to derive maximum performance. Sources at Bosch state that together with turbo- charging, the gasoline direct injection engine generates high power output through the entire rev range. The engine develops up to 50 per cent more torque at low engine speeds, they add. Interesting as it may sound, the extra power and responsive thrust without "turbo lag" saves up to 15 per cent fuel against normal injection systems. So, what remained the domain of diesel for years is now being claimed by the latest gasoline engines--powerful torque for dynamic acceleration even at low revolutions.

At the helm of the technology is the Bosch second generation gasoline direct injection system. Termed as DI-Motronic, the second-generation gasoline injection system contributes to improved mixture preparation and provides for considerably reduced emissions of carbon dioxide (CO2), hydrocarbons (HC) and nitrous oxides (NOx). Using optimized cold-starting combustion processes, which provide for faster heat-up of the catalytic converter, emission values are even below the strictest SULEV (super ultra low emission vehicle) limits in the US. The DI-Motronic, according to industry sources, even has the potential to fulfill future emission regulations. Add sources, the gasoline direct injection system makes combustion more efficient and increases overall engine efficiency. In the current year the company will deliver approximately 900,000 systems. Estimates for 2010 exceed two million.

Interestingly, the combination of turbocharging and second generation gasoline direct injection system has enabled the development of smaller engines, which achieve the same output with a smaller displacement. According to sources these engines also consume less fuel and produce fewer emissions. As a result of the scavenging process, which especially at low engine speeds provides for better filling of the cylinders with fresh air and therefore for high torque, CO2 emissions can be reduced by up to fifteen percent. In other words, a combination of downsizing and direct injection with homogeneous combustion (Lambda = 1) makes it possible to achieve a roughly 15 per cent reduction in consumption. Techniques that would allow further reduction include start-stop systems such as Bosch's direct injection Directstart.

Back to DI-Motronic and the system allows both lean combustion methods with layered charging and homogeneous charge compression ignition to be ideally implemented. The main elements of the DI-Motronic system include the HDP5 high-pressure pump, which is characterized by compact dimensions and low weight. A major contribution to optimum, fuel-saving combustion is provided by the magnetically controlled HDEV5 high-pressure injection valve, which permits a spraying pattern with up to seven individual jets depending on the application. And the HDEV4 piezo injector is also suitable for various combustion methods and injection concepts. It was brought into series production in 2006 as a worldwide innovation in a jet-guided lean combustion process and operates with injection pressures of up to 2,900 psi (200 bar) that enables especially fast multiple injection.

This system was first used in series production in the Mercedes CLS 350 CGI (launched in 2006) and is expected in BMW Group products amongst others. Further developments are also expected as the technology evolvos with time.