I've been shopping for supercharger pulleys lately, and I've noticed that while some respected tuners use aluminum, other make their pulleys out of stainless steel.

I'm questioning which material is better:

- Some say that 6061T6 aluminum is better, because it is lighter than stock, while stainless pulleys are heavier than stock. This makes some sense, even though the radius of the pulley is small. It's worth noting that the SC pulley runds around 3x faster than the crank pulley, so weight reduction here is in the same ballpark as weight reduction at the crank pulley. So why substitute a rotating part that is heavier than stock?

- Others say that stainless steel is better because it is more corrosion-resistant, but these same vendors offer 6061T6 aluminum crankshaft pulleys. Anodized aluminum is pretty corrosion-resistant, and I can't personally see this as being much differentiation, since stainless steel corrodes too - witness what a dishwasher can do to stainless tableware. Why would stainless be important for one pulley, but not the other?

- Another claim is that using different metals (aluminum pulley on a steel shaft) can lead to metal fatigue and loosening of the fasteners and thus the pulley on the shaft, but again, the same vendors that claim this offer aluminum pulleys for the steel crankshaft. An aluminum pulley on a steel shaft is pretty standard engineering practice, so I personally discount this one.

Overall, it seems to me that an aluminum supercharger pulley is a better choice on the balance, but I'd be curious what others might think of the tradeoffs?

 

Careful with using aluminum in contact with the steel shaft. It's a recipe for galvanic corrosion. That area is not a dry area.

http://www.corrosion-doctors.org/Aircraft/galvdefi.htm