sv650lex

I replaced my stock balancer with a set of underdrives a year ago when my stock balancer failed. Now I just got a vortech with 2 different pulleys one is a 3.60 and the other is a 3.30. Can I just run the smaller pulley on the supercharger or will the boost be to low? Anyone tried this or should I just get a good quality sfi approved damper?

Ryan86272

Swap back to stock pulleys...

The UDP's are going to make your small supercharger pulley seem BIG... Waste of boost.. Not sure on how much, I changed before i threw the blower on.

school boy

i would switch back if i was you. it can be done but you can only go so small on a s/c pulley before it starts slipping. say you wanted to run a 3.60 s/c pulley with a factory gt pulley system. i think underdrive pulleys run 15% underdrive. 15% of 3.60 is 3.06. its not recamended to run any lessthan 2.90 pulley because of slippage. so you see, it ca be done but your kinda stuck with that setup. your call man

LilRoush

If you have the UPD on, just run a smaller blower pulley and save yourself the time, energy and money. Make sure your % of change matches.

Blk003GT

And put more wear on the blower than needed? Its too easy change back to stock sell the udp kit.

school boy

what are you talking about??? the smaller pulley brings the s/c back up to the proper rpms as is theres no u/d pullies used. there will be no extra wear!

Blk003GT

Oh so the udp's actually slow down the belt speed. I just saw throw a smaller pully on so I thought spin faster(not thinking about the udp's) which creates more wear.

I stand corrected do what lilrousch said

LilRoush

Yes, if you have an UDP on the crank, you'll need to make up for it with a smaller pulley on the blower to get it spinning the same speed. It's not going to be any different (assuming you match % change) than a stock crank pulley and a larger SC pulley.

grogan

i would spend a little bit of money and buy an sfi rated overdrive pulley. they run about 400 bucks.

just my .02

school boy

i like your idea man. if hes got to pick up a crank pulley he should do it right the first time