More displacement usually means more torque as you are either increasing the bore or stroke. Increasing the bore will make a bigger explosion each time the cylinder fires, and more stroke increases the lever arm. More cylinders usually means more torque and smoother power delivery, as every revolution will have more explosions. Smaller displacement usually allows for a higher redline and more upper RPM range power, as there is less mass in motion with an overall smaller explosion. With a turbo, the number of cylinders will effect how fast the turbo spools, as there will be more exhaust pulses per revolution. Engines with 8-12 and 16 cyl are smoother as the number of cycles per revolution are divisible by 4. There are 360º in 1 revolution, with 4 cycles (intake, compression, ignition and exhaust). In a 4 cyl., there will be 1 cycle per 90º, which is why 4 cyls often feel rough at idle. In an 8 there will be 1 cycle per 45º and so on.