They also lighten the internals. Thats a lot of rotating mass, figure out what the pistons, crank, connecting rods, and all the bearings and bolts weigh. On high RPM engines they have exotic things like titanium connecting rods, light pistons, and usualy timing belts. I guess you can spin a belt faster then a chain.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200