A mechanic got a 4.2L 6-cylinder engine from a 1966 British sports car. It is known that the original compression ratio of the engine is 10.2:1 and the pressure at the end of the power stroke (just before the exhaust valve opens) is 340 kPa. The pistons in the original engine are measured to be 12 cm in diameter. Please assist the mechanic by perform the following calculations:
(a) If the mechanic bores the cylinders and replaces the pistons with new pistons that are 0.5 cm larger in diameter than the originals, assuming the 340 kPa pressure is unchanged, will the engine efficiency change? If yes, by what percentage? Note that "% change" = (new efficiency - original efficiency)/original efficiency.
(b) If the mechanic replaces the engine crankshaft and piston connecting rods, so that the original pistons have their stroke increased by 0.5 cm (0.25 cm on each side), by what percentage will the engine efficiency change?
(c) If the cylinder head is milled so that the original clearance is reduced to 0.4 cm, by what percentage will the engine efficiency change if the engine retains the original stroke?