Revvability of Alfa fours

[C M Smith <cmsmith@domain.elided>]

The big change should have been between the 1570 cc(1600) with a 
bore/stroke ratio of .95 and the 1779 cc(1750) with a bore/stroke ratio of .90.

The 1962 cc(2000) engine had a bore/stroke of .95 just as for the small 
engine it derived from.

Bore/stroke ratio is significant because it gives you an idea of the 
breathing capability of the head relative to the size of the engine. Bigger 
bore breathes deeper and easier.

That said, the 1750 should have been a relative dog with it's enormous 
stroke and teeny, tiny bore ( a mere 2 mm bigger than the much smaller 1600).

The real difference has to be in the valve timing, and possibly lift, 
though the lift should have been comparable throughout the engine range. No 
way the 2000 engine could be more reluctant to rev just because of the tiny 
4 mm increase in bore and no difference in stroke. Piston speed would be 
unchanged and the aluminum pistons would have weighed very little more than 
in the smaller engine. Piston speed for the 1750 and 2000 would be much 
higher than in the 1600. With the right valve timing the 1600 should be the 
rev champion of this series, the 2000 next and the 1750 a distant third.

What really happened here?


Michael Smith
White 1991 164L
Original owner
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