When we vary the pulley size so as to increase boost, which pulley is it that we are changing...

If it were the pulley that is driven, ie, the one on the supercharger, then I imagine it would function like a ten speed bike, where if you decrease the pulley which is DRIVEN, ie, the back one, then you increase speed, but if you decrease the one which DRIVES, like the crank pulley, then that decreases boost.

So, if we increase the crank pulley, we increase boost, and if we decrease SC pulley, we also increase boost..

Despite this analysis, which pulley is actually changed? I would guess its the one on the sC itself, because changing the crank pulley would alter the way all the accessories are driven, which really isnt necessary.

thanks.

Make sure you contact the manufacturer of your SC. I know that powerdyne (my unit) and vortech offer higher boost pressure pulley setups (by changing the pulley size). However, I do not know which one this is. The dangerous part is that they knew what they were doing when they designed the kits for the BMW's. Since our cars have such a high compression ratio, that is what limited the boost pressure to begin with. So, if you figure it out let us know. But if you simply change the pulley size to get more boost, you run the possibility of pre-detonation (pinging) which is the recipe to broken parts and lots of cash!