I'm running a centrifugal d1sc blower on my automatic 5.4L supercrew and have recently added a smaller pulley to the blower, now the problem is the low rpm torque is great, but max boost at max rpm is a little high, I was wondering if anyone uses shiftpoints in their programmers to control boost in a centrifugal setup? I just wish there was a positive displacement kit out there for my 01, to really kick up the boost, but only centrifugals until the 3v motors came out, however, if I can limit my max boost on this procharger by lowering the rpm at wich it shifts, I can actually make pretty good torque down low with the smaller pulley, but as I mentioned before it just climbs a little too high at the top of the rev range. I also live at 6500feet above sea level and want to be able to run safe at lower elevations as with an elevation drop = boost increase. And I don't feel like spending the money to run a blow through system and dumping excess boost via wastegate.

 

A couple of us have added a boost limiter valve much like the turbo guys use. You have to plumb it differently depending on if you are using a blow through or standard mass air. I have been using one for almost a year and it has been working well. I have much better low end boost and torque and can easily adjust what i want for maximum boost with the turn of the adjuster ****.

 

You list 9lbs of boost in your sig. Why do you think that's too high?
My HD has 16lbs of boost with the ported Eaton.

 

Because I'm getting this amount of boost @ 6500' elevation and regularly drive to areas that are close to sea level and I'm sure I'd gain at least 2-3 psi in that condition. 9 isn't too high but that's about the max I want with my trucks stock engine, I don't know, but I'm willing to bet your "harley" truck has lower compression, and stronger internals, than my 4wd 5.4, as your truck came with forced induction from the factory and mine did not. BTW I'm running a ported Eaton pullied for approx.16 psi on my 04 Cobra, torque, torque, torque, and a little bit more torque.

 

I've looked into doing that as well but it seamed to be costly and a bit of a guessing game, but that's refreshing seeing that you've gotten it to work, are you blow through now with the boost controller/wastegate?

 

Jeff

The HD and Lightning has about half a point lower compression to the regular 5.4.
The rest of the internals are the same too.