MAC Autosport swapped out the 3.2 inch diameter pulley on the blower for a 2.85 inch pulley and retuned for me. We also swapped out the Bosch bypass valve with a direct replacement from Forge that is good up to 15 PSI and uses a piston versus a diaphram. Final results were 398 WHP and 319 WTQ. Newest dyno sheet is attached at the bottom of this post.

 

Nice gain ! Almost 11 WHP .
Which blower pulley they used ? Can you send me the exact link for it ?
Thanks

 

The pulley is a stock Vortech part. It is their high traction series which is just like their other pulleys but has some kind of non-slip coating applied to the surface of the area that interfaces with the belt. I purchased the pulley from SuperchargersOnline.com, part number V2A038-285. This is an 8 rib pulley that is swapped out for the pulley that is on the blower itself. Two things to be aware of.

1. The supercharger assembly (bracket, jackshaft, blower, tensioner etc.) must be removed from the car to install this pulley.
2. There is not enough adjustment in the belt tensioner to tighten the belt after this pulley is installed and there are no shorter replacement belts, so we had to order a larger (3 inch diameter) idler pulley. I purchased this from Summit Racing, part number VOR-4FA016-170. It is also a stock Vortech part. However, this idler will not directly replace the existing idler, we had to have a spacer and shaft custom fabricated. The cost for the custom machining was only about $40 though. There may be other idlers that are larger diameter and would be a direct replacement but I do not know of any offhand.

 

Thats great work. But i'm still thinking about shorter belt or as you said finding 3 ince idler pulley with direct replacment . I will do my search and i will get back to you .
Thanks

 

Can you feel the extra hp driving?

 

I was wondering if I would be able to subjectively tell any difference and after driving home then driving around after work on Friday I can definitely say there is a difference. It is probably more related to the fact that the HP and Torque start to build earlier than before. I ended up spending a little more money than I had anticipated because we started with a 3 inch pulley (down from 3.2) and did not see any gain, swapped that out for the 2.85 inch pulley (which forced us to go to the larger idler) and did not see much gain. This led us to replace the bypass valve after which, we saw the gains reflected in the dyno graph I posted. In short, we spent a lot more time than anticpated on the dyno and in labor for swapping out pulleys. Had I opted to go straight to the 2.85 inch pulley on the first try then we would have saved time and money but I was trying to be conservative

 

Bringing this back up, tried to PM the OP but their inbox is full. I know it's been years but are you by chance still out running with this? Checked this and the 370z forum haven't seen updates. Ready to order my Stillen and I'm in Colorado, asked one shop for a quote, looking to hear what you paid for yours. I'll get in touch with MAC as well.