The paper compares V10 F1 engine solutions developed in compliance with the 2001 FIA Technical Regulations. Similarity rules and non dimensional parameters from previous projects are used to define geometric and operating parameters for partly similar engine solutions basically differing in the bore/stroke ratio. Five different bore values are considered, B=94, 96, 98, 100 and 102 mm, thus producing bore/stroke ratios B/S=2.176, 2.319, 2.465, 2.621 and 2.779 respectively. Results are presented as computed classical engine outputs versus engine speed, including brake, indicated and friction values. By increasing the bore size, both power output and engine speed for maximum power operation increase. Conversely, only engine speed increases while torque output reduces for maximum torque operation. By using the sharpest car acceleration criteria, the engine with bore B=98 mm reaches the highest score.