Mahle System Gives Gasoline Engines Diesel-Like Efficiency

Mahle Group's powertrain unit says its latest turbulent jet ignition system has a thermal efficiency of 43% and could reach a diesel-like 45% with hardware upgrades to the engine itself.

The new technology operates exclusively on liquid gasoline. Mahle's previous dual-fuel system required gaseous propane in the pre-chamber, a significant hurdle to commercialization.

The company says its new system enables an engine to run on an air-fuel mixture that is more than twice as lean as that of a standard IC combustion process under part-load conditions, according to company researchers. It also reports that the technology generates low "single-digit" oxides of nitrogen emissions.

Mahle says its turbulent jet ignition, which simply replaces the standard sparkplug in an internal combustion engine, could boost peak fuel efficiency by more than 20%. The company described the technology and presented a technical paper about it during last month's SAE World Congress in Detroit.

The system injects gasoline into a small pre-chamber and spark-ignites it, spraying multiple jets of partly combusted fuel into the main chamber. The approach produces a wide area of ignition sites in the main chamber, thus creating a short and high burn rate.

Mahle researchers say the new system functions successfully at speeds as high as 5,500 rpm and can deliver maximum brake torque without engine knock during near stoichiometric conditions. They theorize that the ultra-high burn rates prevent knocking by consuming the charge in the main chamber before it can auto-ignite.