3.25 pulley ?

[00superchargedSe]

i am going to drop to a 3.25 pulley.. How much horsepower am i looking to gain from 3.5 to 3.25 ?

[SuperSLE]

Depends on the timing and KR. Dropping from 3.5 to 3.25 = huge change in size. I wouldn't recommend it, but hey, what do I know. I dropped to smaller than that. Just going out on a limb here, don't know what you have for tuning, but what is going to happen most likely is you will see KR in the upper range which is going to pull your timing and you will loose power. But maybe not. Just my experience. You'll have to add some fuel.

[2000Silverbullet]

Looks like with the mods you have that you could run with a 3.1 like me.
You should be able to run the 3.25 from the 3.5 with no problem.
Very approximately about 15 -20 hp.

If I were you I would get a 3.0 track and a 3.2 daily

[00superchargedSe]

i have 0 kr with 93 oct with the 3.5... and i am going to add the 104 oct booster with my 3.25 to keep the kr at 0. One problem, i have the M90 ss kit and 3.25 is the smallest i can go without changing out the belt system. Anybody know how to change it over so i can go to a 3.0.. and is the ss intercooler easy to install ? and one last question... how much psi did you push at the 3.0 ??

[willwren]

First of all, don't gauge what you can run by another car. All are different. Second, the 104 octane boost is a joke. Get serious about what you put in your tank. 95% of the products on the market advertise a 2, 3, or 4 POINT increase in octane. If it's 4, and you start with 90 octane, you end up with 90.4 net. It's very misleading, and they like it that way. If it doesn't say FULL POINT as opposed to POINT or POINTS, it's 0.x octane, not x.0 octane. Make sense?

Lastly, judging by boost pressure isn't a good way to go on a supercharged car. Boost pressure is what you're NOT using. Too much boost can be a bad thing. You want to see boost decrease when doing exhaust or head work (or cam/rockers). That means you're actually flowing it and using it. Not just storing and stacking it, which is bad.

[00superchargedSe]

so mixing it your self by buying 103 straight is more better.. and then changing to a leaded sensor ?

[willwren]

No, don't run leaded period. Use unleaded race gas, or Toluene. Be VERY careful though, as 'octane runaway' is very easy to get when mixing subsequent tanks.

Ultimately, your street pulley should be chosen based on the highest octane pump gas (92/93) available to you, and scan on the hottest day.

Your track pulley will be based on the highest octane (to a point, 100 is plenty for most) you can run in those conditions.

Scan, scan, scan, and when you have it, scan to check quite often. Chunked pistons are fairly common. Several of us have had them.

[SuperSLE]

Yeah, I noticed that. After doing my build putting in the cam, going gen V and exhaust work I only see about 6psi on a 3.2 pulley. So you can't really judge how much you would see. Before all the work I did I was at about 16psi on a 3.0 on a ported Gen III which wasn't any faster in the 1/4 then the 3.2.

Toluene and Xylene are great octane boosters. But rather expensive these days. You can use Torco to increase Octane as well. Never mix unleaded and leaded, your car will hate you.

To get rid of the SS kit you have to buy all the idler pulleys that are on regular S/C series II which means the coil bracket and two other idlers that will bolt to the block with minimal work, and a S/C harmonic balancer with the second rib. Then of course the belt.

SS intercooler is very easy to install. But you still need the injector spacers, FMHE, hoses, IC pump, etc to get it going, and good luck finding a location for the FMHE (radiator) in that car.