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Engine efficiency is one of the key aspects to reduce CO₂ emissions. Lamborghini S.p.A. has focused attention on the engine friction modeling, analysis and measurement to understand and control the phenomena. To reduce friction it is necessary to improve understanding of the behavior of the engine components and to pay attention to detail at every tribological contact. The valve train can make a significant contribution to whole engine friction especially at low engine speed and this is particularly true for a high speed sports car engine. Direct acting valve trains are often used for this type of engine to minimize the moved mass and so enable high speed operation. However the sliding contact between the cam and tappet results in higher friction loss than the roller finger follower valve train used on many modern passenger car engines. In addition, the high maximum engine speed demands a large valve spring force to maintain contact between cam and tappet.

This paper presents results of an analytical comparison between two alternative versions of a crankshaft for a 2.2L gasoline engine. The first version had 8 counterweights and a bay balance factor of 80.3%. The second had 4 (larger) counterweights giving a bay balance factor of 56.6% and a crankshaft mass reduction of 1.42 kg. The results presented in this paper relate to the main bearings in terms of specific loads, oil film thickness and shaft tilt angle under full load and no load conditions across the speed range. Torsional vibration analysis and crankshaft stress analysis were also performed but the results are not presented here. The differences in bearing force and oil film thickness were very small and the only major difference in terms of shaft tilt angle occurred at Mains 2 and 4 (increase of ∼ 20% compared with 8 counterweight version).

The main objective of this research was to validate the friction prediction capability of Ricardo Software products PISDYN and RINGPAK by comparing predictions with measured piston assembly friction force. The measurements were made by the University of Leeds on a single cylinder Ricardo Hydra gasoline engine using an IMEP method developed by the University. This technique involves the use of advanced instrumentation to make accurate measurements of cylinder pressure, crankshaft angular velocity and connecting rod strain. These measured values are used to calculate the forces acting on the piston assembly including the friction force. PISDYN was used by Ricardo to calculate friction force at the interface between the piston skirt and cylinder liner. The model used includes the effects of secondary dynamics, partial lubrication and piston skirt profile. RINGPAK was used by Ricardo to calculate the friction force at each piston ring.

This paper describes the design and analysis of a lightweight crankshaft for a high speed racing motorcycle engine. It covers the evolution of the crankshaft from the baseline, with rated speed of 14000 rpm, to the final design with rated speed of 16000 rpm. The lightweight crankshaft is compared with the baseline design in terms of the following criteria. Balance Mass and rotating inertia Main bearing loads and oil film thickness Torsional vibration Stress and fatigue safety factor

This paper describes the design and development of a direct acting valve train for high speed operation in a racing motorcycle engine. At the outset of the project the engine speed limiter was set to 14000 rpm and this was eventually raised to 16000 rpm. The paper covers the evolution of the design and includes descriptions of the components including camshaft, tappet, shim, retainer, valve and valve springs. Valve train dynamic analysis software was used for the following tasks. Assessment of the influence of the changed parts on valve train dynamics and durability Design of new cam profiles Setting speed limit for each build level Investigation of failures These activities are covered in this paper.