Fiat claims Multiair, which is designed for four-valve-per-cylinder engines and combines variable valve lift with turbocharging, can improve power by up to 10%, reduce fuel consumption by up to 10% (in naturally aspirated mode) and cut carbon dioxide emissions by up to 15%. It also makes it possible to downsize a conventional gasoline engine without suffering from the power loss and poor economy of a smaller, less-efficient engine.
The technology works by replacing the twin camshafts that normally open and close the intake valves on a conventional four-valve per-cylinder motor with single cam lobes that control both lift and timing, but in different ways depending on engine speed and required power. Between the inlet cam lobes are hydraulic chambers containing oil that can be released via solenoid actuators to control valve opening. It's so cleverly designed that it could even be used to replace the two camshafts in some current engines and, eventually, in exsiting ones too.
What's more, unlike electronic gasoline fuel injection and common rail diesel technology, which were fuel specific breakthrough applications, the Multiair Electronic Valve Control system can be adapted to use with Spark Ignition engines burning light fuel ranging from Gasoline to Natural Gas and Hydrogen. It also has great potential for reducing Diesel engine emissions too.
Fiat is currently using the technology with its 16-valve 1.4 liter FIRE family of engines, which will be offered in both naturally aspirated and turbo forms. The first car to be sold with a Multiair engine is the Alfa Romeo MiTo at the end of 2009. A 900cc two-cylinder version is due in 2009, which will equip small cars and minisegment vehicles. The 1.6-liter Multiair TwinAir will reportedly be used in some GM pickups and SUVs, including the Corvette and Camaro.