Mercedes-Benz BlueTec Diesel Technology
The recent global recession and higher fuel prices have forced U.S. consumers to re-evaluate what type of vehicle they should own. On top of that, the EPA is mandating significantly higher fuel economy for passenger car fleets. To offset these demands without reducing performance, Mercedes-Benz is sending to the states their new BlueTec clean-diesel engines. Their 3 liter V6 boasts the power of a V8 with the fuel economy of a V6. With diesel engines being 20-30 percent more fuel efficient than gasoline engines, the only thing that has been holding them back is their heavy tailpipe emissions, primarily nitrogen oxides and hydrocarbons which contribute to smog. Mercedes-Benz‘s solution is the BlueTec technology, which makes diesel as clean as any modern gasoline engine.
The 2009 BlueTec diesel models, powered by a Mercedes-Benz V6 engine are available on the GL-class, R-class, and M-class SUVs. The 3.0 liter motor features plenty of new technologies including centrally located piezo-ceramic fuel injectors. Each injector is positioned in the aluminum cylinder head where the spark plug would be found on a four-valve gasoline engine. Designed to spray diesel fuel directly into the center of the combustion chamber, this layout ensures even dispersion of fuel as its flame front spreads concentrically across the combustion chamber. (In conventional two-valve engines where the injectors cannot be centrally mounted, combustion is uneven, so there's less power and higher exhaust emissions).
The secret behind Mercedes-Benz’s CDI electronic injection is its ability to maintain a stratospheric 23,000 psi of constant fuel pressure in each injector. Considered technologically impossible 20 years ago, this layout ensures consistent fuel pressure for the common rail, and the amount of fuel used by the engine is determined solely by how long the electronic injectors stay open. This way, high fuel pressure is always available the instant the injector valve opens, and for as long as it stays open. Taking advantage of the speed and flexibility of their electronic fuel injection, Mercedes engineers also developed Pilot Injection. This involves igniting a small quantity of fuel a few milliseconds before the main injection to pre-heat the combustion chamber and make pressure and temperature increases more gradual. According to Mercedes, this smoothes out combustion pressure and temperature spikes, which softens the usual diesel noise and reduces oxides of nitrogen formation as well. In layman’s terms, you get better fuel economy, more power, and significantly reduced diesel clatter, a win-win situation.
