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On the left is an alloy cylinder
with steel liner bored to 47mm. On the right is a standard cast iron cylinder bored to
39mm. I didn't have a 47mm cast iron cylinder to compare in this picture but with the
exception of the bore size it would be identical to the cast iron 39mm cylinder. The alloy cylinder is 2.4 lbs (1.1 kg) lighter than the iron unit which is a substantial weight reduction on a race bike. Also note the increased size of the cooling fins, not only will the metal of an alloy cylinder transfer heat faster, it will also have more surface area exposed to the air for more efficient cooling. This cylinder came from Mini-4-Stroke in Holland. |