Ferreira, M., Praça, M., and Simão, R., "Lightweight Connecting Rod Design for Flex Fueled Engines," SAE Technical Paper 2013-36-0233, 2013, doi:10.4271/2013-36-0233.
The increasing demand for engines with higher efficiency, reduced fuel consumption and high power density is driving the future engine technologies in the direction of downsizing and reduction of number of cylinders, especially for Otto engines. Specifically the Power Cell Unit (PCU) components are of extreme interest due to its potential for weight and friction reduction.To cope with these demands a new lightweight connecting rod design for flex fueled engines was developed.The combination of thinner web thickness and bushingless small end (coated and profiled), through the optimization by Finite Element Analysis (FEA) simulation, enabled on the new lightweight design a weight reduction of 25% maintaining safe connecting rod fatigue limits in a studied flex fueled engine. The connecting rod bearings were evaluated using Elasto-Hydrodynamic Lubrication (EHL) simulation, and demonstrated suitable results.The connecting rod material selected was the premium 46MnVS6 forged steel. The material fatigue strength is 20% higher than the typical C70 forged steel and allows a weight reduction of up to 30% maintaining the connecting rod structural resistance. Such design also brings benefits for the manufacturing process.To ensure the component integrity, specific bench and engine durability tests were carried out. Detailed description and test results will be available at this paper to support the conclusions.