The FIRE engine family plays a strategic role in FIAT Auto production, since it is installed in all the A and B segment gasoline vehicles of its brands (FIAT and LANCIA), in some key applications of BMPV and C segment vehicles (LANCIA Musa, FIAT Idea, FIAT Stilo), and also in small commercial vehicles (FIAT Doblò and Strada).
In this paper a new FIRE generation is presented. They feature a high internal EGR plus Reverse Miller Cycle system, obtained using a hydraulic vane-type Continuously Variable Cam Phaser (CVCP), which reduces pumping losses at part load and hence increases fuel economy. They also feature variable charge motion systems, which promotes fast combustion rates even with the high EGR rate amounts mentioned above, and limits cyclic dispersion of combustion which is responsible for engine harshness and HC production. These systems are different for 8v and 16v versions: a particular design is used for the intake and exhaust ports for the 8v; and a variable geometry intake manifold with a sliding port de-activation valve for the 16v. All these features are included in a newly designed cylinder head and cover.
Such a concept demonstrated a reduction of about 6–7 % in fuel consumption in the New European Driving Cycle.
In order to reduce friction losses, and so as to further increase fuel economy, the valve-train was completely re-designed in a lightweight fashion for both versions. The camshaft assemblies includes the cam phaser, integrated in the drive pulley, and the trigger wheel, designed to precisely detect the cam phaser position. A torque-based engine management system, which calculates air charge through a double pressure sensor, completes the main features of this engine.
This paper describes these features and the main design characteristics of the two engines in detail.