12A/13B Underdriven water pump pulley

Lightweight water pump pulley made from aircraft-grade 6061-T6 aluminium for light weight, and black anodised for great looks.

Offers faster acceleration through significant reduction of mass having to be accelerated by the crankshaft. The effect is similar to a lighter flywheel, and the car feels more lively and willing to rev.

Pulley outside diameter is 130mm.

Suits early 12A and 13B engines, not S4, S5 or later engines.