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11 hp gained...
Someone was amazed that BMW "only got 11 hp" when they bored and
stroked the 2.5. Well, that's not all of the story, as the most
gain is in torque, what the 2.5 desperately needed. A good example
of misunderstanding the reasoning behind displacement changes is
in looking at the jump in horsepower when BMW went from a 3.0 to a
3.3 in '79 or so in the 6's and 7's. The US 633 got... ONE horsepower
higher than the 630! God, why bother? Well, torque went up nearly
linearly with the displacement, from around 180 to near 200 lb-ft,
and at lower revs than before. Therefore the bigger motor FEELS
stronger off the line, in commuting, etc. where it really counts
for 99% of driving. Same thing happened later with the 3.3-3.5
change. Tiny hp change but lb-ft up 15%...
And with a larger motor, MORE horsepower is possible with
less radical cams, etc.
thi v., who enjoys the torque
of the 2.7 nearly as much as
the scream of the 2.3
'78 323i/327i
'77 320i
'75 2002 for sale
'82 320i