Overdrive SC Pulley Wheel 2.3" & 2.4"

I'm planning to have a run of 2.3" pulley wheels turned by one of our machinists. As most of you already know, these smaller diameter supercharger pulley wheels will allow you to obtain greater boost pressures. Many in this forum have seen success running the 2.3" wheels, though for those of us who want a slight increase, I'm thinking of producing a 2.5" as well.

I'm planning to produce this run from 4140 steel. However, we do have a nice round of 316 SS that looks destined for our government project. If you're interested in a wheel, please reply to this post. I'm confident that we can produce them for a reasonable price (Much more reasonable than those other boys, who will go unmentioned).

If you want more PSI you need to make a smaller pulley. 2.5" is about the stock size.

What is a safe amount or underdrive to put on the S/C without damaging the motor? And i am refering to an otherwise stock motor.

It's not underdrive- it's OVERdrive. That is why you go from 2.5" down to 2.3" for greater boost. The SC will spin faster.

Talith- I would not go any farther than a 2.3" without some type of fuel system change. I saw that the Skyline fuel pump is a possibility, but that does nothing if the fuel rail is limited to a certain amount of delivery. Larger injectors are also a good way to go, but may cause driveability issues when not in boost or while idling. We need a piggyback computer for the stock ECU. I am trying to get Venom to produce one, but I don't think there is enough interest. I just ordered the Service Manual, which provides a complete wiring diagram. I am going to try and install an A'pexi Super AFC (which changes fuel delivery at programmable rpms, not across the whole rev range).

I'll not go below 2.3" with my motor, unless I can get a salvaged SC motor sometime soon and build it into a nice drop-in powerplant. It would be a dream to build up the 3.3 into something really great...then again, the same time could be spent figuring out a way to drop in the 3.5.

A good fuel pump is certainly a necessity, and I'm already suspect of the X's stock pump. Has anyone who is running the 2.3 wheel seen anything they might suspect could be linked to an underpowered fuel pump? I don't know about any latent issues concerning the stock pump and higher boosts.

Have you looked at the Unichip piggyback ECU? Unichip Homepage I know that the other forced induction motors have seen success using them. Check out APS's subaru WRX page. They've got a WRX tweaked out to over 600 horses that apparently accelerates faster than the Lamb. F-1.....Back to terra firma (earth) and the xterra. Though I know little about ECU's, I'm certain that any modification made to the mechanicals of our motors will need to be supported by the programming, or we'll never realize the full performance potential. Heck, there may even be some things that a piggyback system could tweak with stock mechanicals to enhance our performance.

How about using this for adjusting your fuel?

Then again, you would really need an O2 Monitor, an EGT gage, and probably an OBDII Logger to really see what the engine is doing to timing. You could just install a stand-alone computer and remove the stock ECU to have complete control of the Engine.

This is the engine out of the old Z cars right? Shouldn't there be lots of info on the internet on what PSI the stock block can safely take?

I wish it was...but it isn't. The old Z's used the VQ series engine, ours is the VG series - same as in the old pathfinders