2585384 - Introduction - CYLINDER HEAD/S (BIPOWER)

The cylinder head is of aluminium and silicon alloy.The two valves per cylinder, parallel and vertical, are fitted in the valve guides and are operated by a single overhead camshaft with cams acting on mechanical type tappets.The valve guides are an interference fit in the cylinder head seats and the internal diameter is corrected, after fitting, using a special reamer.

The high swirl combustion prechambers (RICARDO) have been designed:

• To reduce rough operation typical of diesel engines
• To optimise fuel mixture with air.
• To guarantee reduced emissions.

The gasket between the cylinder head and the cylinder block/crankcase is the multilayer metal type and there is no need to retighten the cylinder head for the entire life of the engine.The tappet cover, made from a damping material, is designed to carry out the function of an engine oil vapour separator.

Specifications

This type of spherical prechamber, known also as a high turbulence prechamber, allows the air mass to swirl and pull through diesel sprayed by an injector on the prechamber to make the mixture more even and aid combustion.

Current developments

Unlike conventional bottom inserted prechambers, the RICARDO prechamber is designed specifically for the FMA engine line (engines built at Pratola Serra). Although the prechamber is TOP INSERTED (inserted from the top of the cylinder head), the machining centre lines on the cylinder head remain unchanged as on current engines.

System features

Adoption of this type of RICARDO prechamber allows this engine to meet emission limits imposed by EC STAGE 3 regulations:

• reduce fuel consumption compared with current prechamber engines;
• develop considerable torque at low speeds because combustion is more efficient due to the higher swirl generated by the prechamber;
• increase acoustic comfort due to the special type of smooth combustion offered by the RICARDO prechamber.