FRANKFURT -- Mercedes-Benz has developed a four-cylinder engine family that will power the upcoming A-, B- and C-class lineups in the United States.
Ranging from 1.6 to 2.0 liters, the turbocharged gasoline direct-injection engine could offer torque ranging from 185 to 260 pounds-feet, depending on displacement, said Bernard Heil, Daimler AG vice president of powertrain development.
With help from two fully variable camshaft phases, those torque figures could come on at as low as 1,250 rpm and run at full load up to 5,000 rpm without problems with cooling -- impressive for a small-displacement gasoline engine, Heil said in an interview at the auto show here.
He said the technology could generate more than 100 hp per liter of displacement -- a figure once achieved only by racing engines.
"We're talking horsepower equivalent to high-displacement V-6 engines but with four-cylinder fuel economy," Heil said.
The four-cylinder debuts in the United States in the midcycle revision of the C class now arriving at dealerships. The 1.8-liter turbo in the C250 sedan and coupe generates 201 hp at 5,500 rpm and 229 pounds-feet of torque between 2,200 rpm and 4,300 rpm.
The engine family has an aluminum block and head like the four-cylinder currently offered in Mercedes models sold in Europe. It uses a piezo direct injection system from Robert Bosch. The piezo injector is electronically controlled and much faster at regulating fuel delivery compared with traditional solenoid actuation, resulting in a cleaner fuel burn and lower emissions.
Also, the injector has been moved from the side to directly over the combustion chamber, where the spark plug normally resides. Heil says the technology allows the injector to spray fuel while the plug pre-ignites it.
Meanwhile, Mercedes' joint-venture with IHI Group has resulted in a turbo with improved efficiency and power delivery, Heil said. Mercedes also has a new design for its oil pump that results in less energy drawn from the engine, he said.
Heil said Mercedes also will import stop-start technology for the U.S. market with the new engine. He declined to give the additional cost for stop-start technology but said the system requires an electrical power-steering system and an electrical oil pump to keep the transmission bearings lubricated while the engine is stopped.