GFB lightweight pulley kits are made from aircraft-grade 6061-T6 aluminum and offer faster acceleration through significant weight reduction on the crankshaft.
Most of our kits are under-driven, which means the accessories are driven slightly slower to reduce parasitic losses. GFB pulley kits are designed to improve acceleration by reducing the rotational mass (inertia) on the crankshaft as well as parasitic loads from the driven accessories. The effect is similar to a lighter flywheel, and the engine feels more lively and willing to rev.
We know that people are sometimes concerned about possible adverse effects of lightweight pulleys and under-driving, but rest assured we have done our homework! The under-drive ratios have been optimized to ensure there are NO adverse effects on the performance of the accessories, and whilst it is true that some engine types do suffer harmonic issues from lightweight pulleys, we steer clear of those. The kits we release are thoroughly application tested and do NOT cause engine damage in the short or long term.