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Dielectric testing is essential in developing ceramic insulators for spark plugs used in modern engine platforms. Many test methods are developed for different materials and applications. At Autolite, parallel plate dielectric testing based on the ASTM standard was used for material evaluation. The paper will cover the factors that influence the measurements in these tests as well as a comparison of insulator materials from different spark plug manufacturers. Furthermore, to better evaluate the performance of final product, Autolite developed a proprietary engine dielectric test method for spark plugs. The test method is compared with most conventional tests in the automotive industry, and the performance of spark plugs using Autolite conventional and next gen ceramic will be reported.

The addition of exhaust gas recirculation (EGR) has demonstrated the potential to significantly improve engine efficiency by allowing high CR operation due to a reduction in knock tendency, heat transfer, and pumping losses. In addition, EGR also reduces the engine-out emission of nitrogen oxides, particulates, and carbon monoxide while further improving efficiency at stoichiometric air/fuel ratios. However, improvements in efficiency through enhanced combustion phasing at high compression ratios can result in a significant increase in cylinder pressure. As cylinder pressure and temperature are both important parameters for estimating the durability requirements of the engine - in effect specifying the material and engineering required for the head and block - the impact of EGR on surface temperatures, when combined with the cylinder pressure data, will provide an important understanding of the design requirements for future cylinder heads.