Engines: what does having more cylinders do?

[ShawnD1]

If I have 2 engines, each having the same compression, same displacement and burn the same amount of gas, what will the difference be if one has 6 cylinders and the other has 8 cylinders?

[nunyadam]

well for one you can balance the power more evenly with eight cylinders.

[nunyadam]

one piston firing every 45° of the 360° of rotation on the 8.
where on a 6 it would be 60°.

In most cases, more power. As Nunya said, you get a better balance and each piston has to work less to turn the motor. That's why old jags have V12s. They're not monster 500 displacement engines. They're actually very small pistons, but since there are so many, they make power more easily. Oh, and more cylinders = less gas milage in just about any equation.