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Engine friction typically accounts for 10 - 20 % of the power output of an engine, and friction in the power cylinder assembly is responsible for 50 % or more of the total engine friction. Hence, improvements to this assembly are critical for maximizing mechanical efficiency in high-performance and race engines. Many strategies have been developed and are currently being employed with the intent of reducing engine friction and extracting additional engine power. However, quantitative proof of their effectiveness has been very limited. This paper discusses the design and development of a research grade ‘floating-liner’ engine for measuring the friction forces within the power cylinder assembly of a high-speed internal combustion engine.

Specification (spec) race engines are intended to reduce costs and increase the competitiveness in many racing classes. However, engines prepared by the best race engine builders routinely outperform truly ‘standard’ engines or engines prepared by less experienced tuners. This paper describes how engines can be modified to increase their power output and discusses various spec engine preparation techniques. Experimental and computational evidence is used to quantify the potential benefits that can be expected from each of the modifications discussed. By combining several relatively small improvements, a well prepared engine may be expected to enjoy a 5-8 % power benefit over an ‘average’ race engine, and perhaps as much as a 14-17 % benefit in power versus a truly standard production engine off the assembly line. This analysis also reveals the claims of much larger power improvements by some high-performance engine tuners can not be substantiated unless further modifications are made.