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In a multi-cylinder engine, the harmonics of pressures in different cylinders add to excite the crankshaft and other mass-elastic system in its line. The predominant component builds up the shear stress at resonances of the system, if the natural frequencies lie in the operating range. Addition of a tuning disc in the form of a rubber damper increases the order of the system by one. The nuisance frequency is substituted by two new damped frequencies. The design of rubber for operating at high temperatures and for withstanding high shear is important. The known procedure of calculations is systematically reviewed in this paper. The importance of properties of rubber is given in detail. A successful study of damping a large 8.8 litre turbocharged and aftercooled engine rated at 2200 rpm is used to demonstrate the procedure to design a rubber damper.

Engine up rating is not unusual in these days as the need is felt for more energy output from the same volume of the cylinder. This has increased the brake mean effective pressures in the internal combustion engines. The power train components are highly loaded as the peak firing pressures are required to be on the higher side. The connecting rod of such a highly loaded engine was designed with bmep of 2.3 MPa. To overcome the initial failures of the connecting rods it was realized that the critical design review was essential. Classical calculations and FEM studies revealed the stresses in the critical sections. The failures were overcome by the improvements in the geometry of the specific zones. The machining process improvements were necessary to reduce the stress concentration at the bottom of the blind drills. To avoid the rotation of the small bearing bush the surface finish of the connecting rod, the parent bore was improved by burnishing to get better profile metal ratio.

The piston slap is an important phenomenon in the engine, which governs the vibration, noise, and wear of liner surfaces. It occurs due to transverse and rotational motion of piston, which depends on clearance between piston and liner and is governed by geometry, mass and inertia properties of reciprocating parts, and gaseous loads. Piston slap is studied on single cylinder high-powered engine, which showed large vibrations and noise during the field trials. The classical methodology is used to determine secondary movement, contact forces and kinetic energy loss due to piston impact. The calculated result showed no major impact of piston on liner surfaces due to presence of hydrodynamic lubrication between two mating surfaces. The loss of kinetic energy due to the impact is of the order of 0.007 Nm, which is negligibly small.