MultiAir: how does it work?
The system developed by Fiat is made up of a piston moved by a mechanical intake cam. The other end of the piston acts on a small oil-filled chamber. The volume of oil in the chamber is controlled by a solenoid valve through an onboard electronic engine management system. When the chamber is full, it acts as a solid link between the cam and the intake valve allowing usual full opening and closing of the valve. Changing the volume of oil in the chamber then allows partial opening of the valve or even no opening at all. This allows full control of valve lift and phasing and even multiple opening of the valve for each cycle, i.e. “multilift”.
Among the benefits of MultiAir: elimination of the throttle valve for controlling engine speed, thus eradicating the energy lost due to pumping losses; a 10% increase in maximum power; a 15% increase in low rpm torque; a 10% decrease in fuel consumption and CO2.
One must also add to these significant results the fact that MultiAir is an affordable technology, especially when compared to the high cost of hybrid powertrains. For a 4-cylinder engine, the MultiAir system which is grafted to the cylinder head is the size of a carton of cigarettes and adds very little weight to the overall engine compared to the heavy and bulky battery pack and electric motor of a hybrid. As mentioned earlier, MultiAir requires no other change to the basic engine other than a specific cylinder head.
Less weight. Less fuel. More power and torque.
According to Dr. Rinolfi, MultiAir will have a significant impact on the industry by allowing fundamental changes in powertrain usage: “Take for instance our 4-cylinder 1.4 litre FIRE gasoline engine. By combining MultiAir and turbocharging, this engine produces 165 horsepower and maximum torque starting at 1,700 rpm, in other words higher performance than a good 2.5 litre standard engine. With MultiAir and turbo, we can also have a 900 cc 2-cylinder engine with the same output as a 1.5 litre 4-cylinder motor. Moving to a 3 litre V6, MultiAir and turbo allows for more than 350 hp, which compares to a healthy V8. Remember that this substantial increase in performance is also coupled to very low fuel consumption and low emissions and an overall reduction in vehicle weight.”
Will MultiAir replace hybrid as the preferred “green” solution? Difficult to say for now, but Fiat firmly believes that the good old internal combustion engine has still “a lot of breathing” to do.
photo:Fiat
The system developed by Fiat is made up of a piston moved by a mechanical intake cam. The other end of the piston acts on a small oil-filled chamber. The volume of oil in the chamber is controlled by a solenoid valve through an onboard electronic engine management system. When the chamber is full, it acts as a solid link between the cam and the intake valve allowing usual full opening and closing of the valve. Changing the volume of oil in the chamber then allows partial opening of the valve or even no opening at all. This allows full control of valve lift and phasing and even multiple opening of the valve for each cycle, i.e. “multilift”.
Among the benefits of MultiAir: elimination of the throttle valve for controlling engine speed, thus eradicating the energy lost due to pumping losses; a 10% increase in maximum power; a 15% increase in low rpm torque; a 10% decrease in fuel consumption and CO2.
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| The system developed by Fiat is made up of a piston moved by a mechanical intake cam. |
One must also add to these significant results the fact that MultiAir is an affordable technology, especially when compared to the high cost of hybrid powertrains. For a 4-cylinder engine, the MultiAir system which is grafted to the cylinder head is the size of a carton of cigarettes and adds very little weight to the overall engine compared to the heavy and bulky battery pack and electric motor of a hybrid. As mentioned earlier, MultiAir requires no other change to the basic engine other than a specific cylinder head.
Less weight. Less fuel. More power and torque.
According to Dr. Rinolfi, MultiAir will have a significant impact on the industry by allowing fundamental changes in powertrain usage: “Take for instance our 4-cylinder 1.4 litre FIRE gasoline engine. By combining MultiAir and turbocharging, this engine produces 165 horsepower and maximum torque starting at 1,700 rpm, in other words higher performance than a good 2.5 litre standard engine. With MultiAir and turbo, we can also have a 900 cc 2-cylinder engine with the same output as a 1.5 litre 4-cylinder motor. Moving to a 3 litre V6, MultiAir and turbo allows for more than 350 hp, which compares to a healthy V8. Remember that this substantial increase in performance is also coupled to very low fuel consumption and low emissions and an overall reduction in vehicle weight.”
Will MultiAir replace hybrid as the preferred “green” solution? Difficult to say for now, but Fiat firmly believes that the good old internal combustion engine has still “a lot of breathing” to do.
photo:Fiat
