The Petrol Engine Cylinder Block Reinvented: Cast Iron with the Same Weight as Aluminium

Authors

Dr. C. S. Cabezas, C. L. F. de Andrade MSc, J. A. Brzostek MSc, Dr. L. C. Guedes, Dr. W. L. Guesser, Dr. R. Marquard, Tupy Fundições, Brasil; M. Jeremy, E. Zents, Ricardo Ltd, United Kingdom; Dr. S. Dawson, SinterCast AB, Sweden:

Year

2022

Print Info

Production/Publication ÖVK

Summary

Compacted (Vermicular) Graphite Iron (CGI, GJV) has become the default material for V-diesel passenger vehicle cylinder blocks and for heavy-duty cylinder blocks and heads. However, there has not yet been a high-volume series production reference for CGI in small, in-line petrol engines. In order to demonstrate the potential benefits of CGI for in-line petrol applications, the present study converted the cylinder block of a state-of-the-art series production 1.2 litre three-cylinder engine from aluminium to CGI. The revised engine was simultaneously upgraded to a 48-Volt hybrid configuration to further demonstrate the potential of CGI in hybrid and range-extender applications.

Leveraging a novel design concept, with the running surface and load path constructed from high-strength CGI and the outer crankcase housing fabricated from durable, lightweight plastic, the assembled cylinder block achieved the same weight as the original aluminium block. However, it is noted that the design of the CGI cylinder block was constrained by the need to maintain outer dimensions and bore-centres to facilitate engine assembly for durability testing. It is estimated that a clean-sheet design approach would have enabled a further 5% reduction in the weight of the CGI cylinder block.

NVH modal analyses showed that the global flexural modes of the CGI cylinder block were approximately 5% higher than original aluminium block while the four main bearing cap modes were 18~40% higher, indicating potential NVH advantages for the CGI engine. The CGI cylinder block successfully passed 100-hour durability, including testing at peak load. With weight parity – and the inherent advantages of cast iron for mechanical properties, parent bore running surfaces, fracture split main bearings, cost, recyclability and lower life cycle CO₂ – Compacted Graphite Iron has established a new benchmark for small, in-line passenger vehicle petrol engines.

ISBN

1920-2323-23-1

Number of pages

19 Order