Quote:
Originally Posted by mkoesel
I had crafted a fairly involved response to this, but realized that it was more complex than I thought at first.
But, in short, cylinder count plays a role because, while it does not change total piston area, it does effect area per combustion event. So, assuming we have two engines with the same displacement, same stroke, same effective RPM range, but different cylinder count, the one with fewer cylinders theoretically has the torque advantage. This could partly explain why Porsche's H6 (in its most evolved form) has higher peak torque than BMW's S65 V8 at similar RPM.
But yes, generally speaking torque is displacement-bound (while power is RPM-bound). Most naturally aspirated production cars make somewhere in neighborhood of 75-85 ft-lbs of torque per liter at peak, whether they are econoboxes with tiny three or four cylinder engines or supercars with huge V12s.
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I am not sure I follow you here. For a total cycle (2 complete rotations), the area exposed to cylinder pressure should be the same regardless of cylinder count.
However, an engine with a larger cylinder count will have more friction losses. Just considering the piston/cylinder interface, the bigger pistons have a better area to circumference ratio.