Ok. For starters I own a 91 1LE formula 305. I have an SN92 with the SN93 upgrade.

I had a 4.5" pulley on there producing about 4lbs of boost.

Tonight, I switched to a 3.25" pulley with the proper belt. I gained about 3 extra lbs of boost. Now heres the problem. At around 4100 RPMS, a screeching sound is present. It only happens when I "punch" the throttle. If I take the car up to 4100 RPMs slowly, the sound isnt there. Only when I punch it. I know I cant be over revving it????? can I?

With a 6" crank pulley and 3.25" blower pulley, my Paxton redline is 4700 RPMS. I use a MSD shift light I set specially with a adjustable RPM limiter and my auto xray so I'm positive I have it set correctly. What can cause this sound? Could it be belt slippage? Should I tighten the belt? Does a loose blower belt sound like someone burning their tires? Know what I mean? Or is it the blower ? It never made any noises with the other pulley

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91 Formula 1LE 1 of 46
305 TPI 5speed
1LE/G92/WS6

Paxton SN92 supercharger(SN93 upgrade), Ford SVO 24#injectors, Crane AFPR,SLP airfoil, ported/polished plenum, March alt. pulley,Crane Gold 1.6rrs,MSD coil,MSD6AL (5200rpm limit),Holley 9mm wires,Ac delco R43ts plugs,custom chip,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,170* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

 

I had the same problem with my sn2000 Paxton,
just tighten the belt a little at a time untill the squeal goes away.
You don't want to overtighten it.

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Louis
Convertable
92 Z28 305tpi Auto
1/4 at 13.23 @ 106.1mph w/Paxton 10psi, Ram air mod,Water methanol inj.,52mm T/B,ASM Large tube runners, ported upper & lower intakes,AFPR,23# injectors,1.6 roller rockers,slp tri-y headers,3in. cat,3in. gale banks cat back system,3.42 gears,17x9 camaro SS wheels, 285x40x17 tires,and much more.
http://www.lbsz28blown.cz28.com

 

Ok thanks man you were right. Problem solved.