pulley install questions

[hey its me]

Hello all, I am new to this forum and new to the sn blower as well so i need some help. I have an sn92, newly rebuilt on a 92 GT i just bought. Right now it has all stock pulleys, an anderson power pipe, and it looks like its at about 3psi.

First off, my boost guage is old and doesnt sit at 0 when the cars off, does this effect anything?

Second, i just ordered a 4" pully from paradise wheels, and am looking for tips on installing. I assume its easy but am wondering how tight belt should be? do i needa new belt?

Also how much power gains, boost gains should i see?

Thanks for any help, its well appreciated.

[444]

Hello all, I am new to this forum and new to the sn blower as well so i need some help. I have an sn92, newly rebuilt on a 92 GT i just bought. Right now it has all stock pulleys, an anderson power pipe, and it looks like its at about 3psi.

First off, my boost guage is old and doesnt sit at 0 when the cars off, does this effect anything?

Second, i just ordered a 4" pully from paradise wheels, and am looking for tips on installing. I assume its easy but am wondering how tight belt should be? do i needa new belt?

Also how much power gains, boost gains should i see?

Thanks for any help, its well appreciated.

If it's a boost/vacuum gauge not reading at 0 is pretty common. These gauges seem to have a hard time zero-ing out. So if your boost gauge reads 2" vacuum when the engine is turned off, you're actually making 5psi not 3. For example. Sometimes gauges can be adjusted to reset them with a set screw on the back or take the lens off, most cheapies can't be adjusted.

[hey its me]

oh ok thats what i thought. guy at O' Reily said it doesnt matter, so good thing I checked. So I installed my 4" pulley. I wasn't expecting much but i was suprised i didnt see more boost. before i saw about 3psi, now i see about 4 or 4.5 at about 5,000 engine rpms. Craig at paradise said i should be seing about 5 or 6? is this right? do i need to change to a smaller belt so i dont have to move the belt tensioner down as far?

by the way my engine is all stock, except the anderson powerpipe, electric fan, exhaust..

[CiDhed]

What impeller?

[JPJP]

Get as small a belt as you can squeeze on there.

[hey its me]

I'm sure its the stock sn92 impeller. and im pretty sure it was rebuilt locally. Ok will get a smaller belt this week. Will this help the boost? and you think this is why im only getting about 4 psi instead of 5-6 like i was told i should get? help help!

[JPJP]

In my case it helped w/ the boost (smaller belt), getting that belt on tighter. When I first put the kit together I had my dad drive it and he came back saying the belt is slipping at the higher RPM's. I don't have a gauge but even w/o it you should be able to tell if you pay close attention. Of course a slipping belt will leave belt dust residue too. Some people recommend Gaterback belts as they are supposed to slip less.

I am running a 3.75 Dia. pulley and usually run the car a few minutes to loosen/heat up the belt a little. I will admit the Mustang kit does not allow very much for belt adjustment. This makes getting that shorter belt on a pain. I am assuming you have a 5.0 Mustang.

[hey its me]

Yea i can tell its sipping a little cuz I can watch the boost go up, then stop at about 4psi, ( as engine rpms are still increasing) it then drops down to about 3psi before i shift into the next gear.

Yea I have a 92 GT. hmm in this case, mybe I should get a half inch smaller belt, put it on and run the car for a bit. then push it down and re tighten the tensioner as much as i can.
what do ya think? any other tips?

[JPJP]

Sounds good. I recommend you get a 1/4 inch smaller belt AND a 1/2" smaller belt. Then find which one still fits and return the one you don't use. It is surprising how little adjustment there is on the set up.

[steel1]

I used a 49" Gatorback belt on my 93GT w/SN89, great fit and I haven't noticed any slipping.

[steel1]

Sorry^^, it's a 4" s/c pulley, 6" crank.

[speedytang]

Something else to watch for is the bracket is weak and is moving with your rpm. The crank pulley is pulling against the pulley and moving the bracket. This happens after years of stress on the bracket. To check if this is your problem stand to the side and watch the supercharger while snapping the throttle. If you have this problem you will see the 'SN' move inward and the belt start to slap because of slack of the supercharger moving.

[JPJP]

Glad to hear no slipping. What is your gauge showing now?

[steel1]

Showing 5-lbs. boost

[Granatelli]

When this kit was sold new Model number 18001 for 88-93 Mustangs it came with 4.25 blower pulley and 6 inch crank. Required belt was Gates KO60500. it made 5psi at 6k

Next came 4.00 blower pulley and used KO60495 belt and should have made 6.5 to 7 psi.

then 3.75 used KO60490 and should have made 8.5 psi

3.50 and 3.25 used a KO60480 and a larger idler pulley for tension