[net.auto] 'v8, sixes and torque'

keithe@teklabs.UUCP (06/13/83)

A recent article mentioned the superiority of a V8 in the low-end
torque department. I always thought a 6 cylinder had the better low-end
torque, but that the V8 would have a broader torque-vs-rpm curve.
Isn't that why the hi-class racing engines use 12 (smaller) cylinders
than a 6 or an 8? And isn't that why the Ford 300 cu in 6 cylinder
is a preferred truck engine over the 302 V8?

keith ericson at teklabs

rs55611@ihuxk.UUCP (06/14/83)

Yes, your point is basically correct.  Perhaps a better statement 
is that larger engine displacement provides greater torque, and since
most V-8s are larger than most sixes, typical V-8s have greater torque.
As you said, however, if you compare an 8-cylinder and a 6-cylinder
engine of equal displacement, the six will typically provide more torque.
The disadvantages of the equal-size six are 1)lack of smoothness, compared
to an eight, and 2)higher piston mass and inertia.

Thus, the equal-size eight would probably rev higher (given a supportive
valve train), and could have other advantages in terms of more even
fuel burning in the smaller cylinders.  As another example, old
BSA single-cylinder 500 cc bikes (thumpers?) have great gobs of
torque, but are very tiring to ride, from all the vibrations.