In 1985, Lamborghini made the biggest improvement to Countach.
The V12 was stroked to 5,167 c.c., incorporated a 4-valve cylinder head
(called "Quattro-valvole" in Italian, which gave its name "QV") thus a total of 48 valves.
Power jumped to a world-beating 455 hp, torque rose to 369 lbft.
Finally, the Countach produced more power than the originally proposed LP500 prototype,
which would have been capable of 440 hp from 5 litres of displacement.
Displacement 5.167 liter
Power 440 bhp @ 7500 rpm