Rejowski, E., de Souza, J., and Rabello, R., "New Coated Cast-In Liner to Improve Heat Transfer on Aluminum Blocks," SAE Technical Paper 2016-36-0262, 2016.
Engine development activities are being driven forward primarily by the challenge of continuing to reduce CO2 and exhaust emissions. From the piston/liner system it is well known that Lube Oil Consumption (LOC) is affected by the bore distortion occurrences within Internal Combustion Engines (ICE) that usually demands a redesign on the piston ring pack not in favor to reduce friction losses. This article shows a potential solution to reduce bore distortion and oil evaporation through more efficient heat dissipation from combustion chamber to engine cooling system in a modern aluminum Spark Ignition (SI) block. Electroplated nickel coating applied to the external cast iron surface previous to the casting process enable a metallurgical diffusion layer with the aluminum block material and therefore improve heat conductivity in fired operation conditions compared to conventional cast iron liners. The improvement of the heat dissipation rate reduced the bore distortion and therefore LOC as proven by engine tests. In this paper, results of engine dyno tests to build up LOC maps using Real Time Lube Oil Consumption (RTLOC) by mass spectrometry are presented. The application of nickel coated liners showed LOC reduction up to 75% in certain engine operation conditions. Detailed information about the coating and diffusion layer of Fe-Ni-Al is also presented by Energy Dispersive X- Ray (EDS) and Scanning Electron Microscope (SEM). Finally comparative analysis of bonding strength on aluminum blocks and thermal conductivity measurements by thermocouples installed on aluminum blocks engine test is presented to consolidate the nickel coating technology.