What kind of issues does a smaller pulley on their supercharger cause?

[pvan]

I just dug my blown valk out of storage and this winter was reading a Mini Cooper Eaton 45 tuner named KAUMOTORSPORT.COM has a variety of smaller pulleys that offer significant performance gains.

I am sure some of you blower boys have tried smaller pulleys and am curious what kind of success and issues you have faced?

Have any of you used KAUMOTORSPORT pulleys?

Please advise and thanks

[BonS]

I have a blower but haven't reduced the driven pulley. Doing so will certainly increase the boost pressure, of course, and will produce more power in kind. Issues? To avoid over stressing the pistons you'll need to use forged pistons after getting in the range something like 10-14 psi (stock being ~7 psi). And to help things breathe better porting the head and a free flowing exhaust to move the extra volume of gases. The down side? First and foremost is heat: getting rid of it. Your link to KAUMOTORSPORT.COM doesn't work for me. Others here have far more experience with blowers around here and hopefully they'll chime in.

[Patrick]

I don't know much about superchargers on the Valk except for the problems listed here over the years, but, I've played with blowers for 40yrs.. Decreasing the size of the blower pulley will speed up  the blower increasing pressure.. From what I've seen on Valk blower manifolds there is no baffling which can cause overpressure/ uneven pressure on some cylinders which can break pistons.. So increasing pressure much on these engines would require forged pistons.. Its my understanding that original pulley diameter creates about 5-7# and increasing that pressure by only a couple pounds is considerable..