[Mustang_Girl_32]

Ok so I don't understand a whole lot about how the pulley functions along with its size to how much psi you get out of it. However my question is being that mine has a 3.09 supercharger pulley on it and I was given the stock idler pulley for the 00-04 mustang application last night. Due to the fact the 99-01 cobra pulley is a bit bigger. Anyway I kinda wanted to know if that pulley is going to work for me and what psi I will be looking at? I am new to this whole thing so, be easy on me. I am learning slowly

[Shaun03GT]

I believe a 3.6 pulley will net 10psi with a 3 core intercooler. 3.09 is to small for the stock motor.

[Mustang_Girl_32]

Great... So what one should I get? I believe I have a 3.9 or 3.09.

[Eagle2000GT]

A P1SC normally ships with a 3.85" or 3.7" pulley. The 3.85" is normally considered an 8 psi pulley. The 3.7" pulley gets you around 9 psi. I'm running a 3.7" pulley and get 8.9 psi at 6000 rpms. If I push the motor up to 6200-6300 rpms its 10 psi. In general for every 1/10th inch smaller pulley you get 1 additional psi. A 3.0" pulley would be somewhere around 16 lbs of boost. That is far more than you want to run on a stock motor.

The size of the idler pulley doesn't affect this at all. Its purpose is make the belt have more contact on the pulley to help prevent belt slippage. The reason we have the smaller 1.95" idler pulley is to keep it from rubbing against the water pump pulley. There should also be an offset space in the kit that attaches to the bottom of the altenator lifting it farther away.

The P1SC has an internal 4.10 gear ratio. To calculate the impeller speed you divide the crank pulley size (stock is 6.5") by the supercharger pulley size multiply by 4.10 and multiply again by the engine rpm. At 6000 rpms mine is spinning at 43,216 rpm (6.5/3.7 x 4.10 x 6000). A 3.0" pulley with a stock crank pulley would be spinning at 53,300 rpms and as mentioned before generating somewhere around 16 psi (it is not a precise estimate). The smaller the supercharger pulley the greater the chance for belt slippage. More force is needed to turn the supercharger and there is less belt contact.

Another way of generating the same boost (same impeller speed) having a larger supercharger pulley is to increase the size of the crank pulley. For example, a overdrive 7.25" crank pulley and a 3.4" supercharger pulley will get you about the same amount of boost.

Edit: 3.9 to 3.09 is almost an inch difference. You can measure the diameter of the pulley with a ruler. Be sure to measure the inside part that the belt rides on and not the entire pulley.

[HighDensity]

Originally Posted by Eagle2000GT A P1SC normally ships with a 3.85" or 3.7" pulley. The 3.85" is normally considered an 8 psi pulley. The 3.7" pulley gets you around 9 psi. I'm running a 3.7" pulley and get 8.9 psi at 6000 rpms. If I push the motor up to 6200-6300 rpms its 10 psi. In general for every 1/10th inch smaller pulley you get 1 additional psi. A 3.0" pulley would be somewhere around 16 lbs of boost. That is far more than you want to run on a stock motor. The size of the idler pulley doesn't affect this at all. Its purpose is make the belt have more contact on the pulley to help prevent belt slippage. The reason we have the smaller 1.95" idler pulley is to keep it from rubbing against the water pump pulley. There should also be an offset space in the kit that attaches to the bottom of the altenator lifting it farther away. The P1SC has an internal 4.10 gear ratio. To calculate the impeller speed you divide the crank pulley size (stock is 6.5") by the supercharger pulley size multiply by 4.10 and multiply again by the engine rpm. At 6000 rpms mine is spinning at 43,216 rpm (6.5/3.7 x 4.10 x 6000). A 3.0" pulley with a stock crank pulley would be spinning at 53,300 rpms and as mentioned before generating somewhere around 16 psi (it is not a precise estimate). The smaller the supercharger pulley the greater the chance for belt slippage. More force is needed to turn the supercharger and there is less belt contact. Another way of generating the same boost (same impeller speed) having a larger supercharger pulley is to increase the size of the crank pulley. For example, a overdrive 7.25" crank pulley and a 3.4" supercharger pulley will get you about the same amount of boost. Edit: 3.9 to 3.09 is almost an inch difference. You can measure the diameter of the pulley with a ruler. Be sure to measure the inside part that the belt rides on and not the entire pulley.

+1

[Mustang_Girl_32]

I also have the 2 core intercooler. What pulley do you suggest I get? Because I have read over that twice and I still can't quite comprehend it.

[Mustang_Girl_32]

I probably need to go out there and measure it..

[HighDensity]

Originally Posted by Mustang_Girl_32 I also have the 2 core intercooler. What pulley do you suggest I get? Because I have read over that twice and I still can't quite comprehend it.

With everything else stock, I would get one of these two:

3.85 (around 8psi)
3.4 (around 10psi)

^ I would NOT go any smaller than that on an otherwise stock engine

Your 2 core intercooler will be fine at those boost levels.

[Shaun03GT]

It should say on the pulley. With a 2 core, I think you want a 3.4 pulley to hit 10psi. Don't take my word for it.

Listen to eagle, he's very knowledgable with prochargers.

[HighDensity]

Originally Posted by Mustang_Girl_32 I probably need to go out there and measure it..

One way is to wrap some string around the pulley, then spread the string out into a perfect circle, then measure

[Mustang_Girl_32]

I will let u know here soon what pulley I have because I believe I saw numbers on it. That's where I was coming from with the 3.09 or 3.9 but I don't see why it would be a 3.09 if that would just be extremely too small and wouldn't even remotely work.

[HighDensity]

One thing, and this may have been already discussed in your other threads, the stock bypass valve crapped out on my original P1SC kit which caused surge in the head unit so it started to leak. I now have a D1SC with a Vortech mini-race BOV without any problems. ProCharger also makes one, the Big Red, but I cost significantly more than the Vortech mini-race BOV. The Vortech mini-race BOV is about $125-150 CHEAPER than the BIG RED.

[Mustang_Girl_32]

Alright.

[Eagle2000GT]

HighDensity may have just had some bad luck. Or else I've had good luck. I've got 76,000 miles on the standard ProCharger BOV.

[Mustang_Girl_32]

It is a 3.90. What it said on the pulley. Will it absolutely not work or would I just be better off going with a 3.70?

[Shaun03GT]

It will work, but you won't make a lot of boost. Maybe 6-7psi? Is go down to a 3.4. Just throw it up on corral, you want to trade for a 3.4 or sell it. Might be someone who just upgraded to a d1 and needs a bigger pulley.

[Mustang_Girl_32]

Alright. That's what I will do. Do I need to go to procharger for my pulley?

[Shaun03GT]

You can get them from a lot of places. Just Google search shopping procharger 3.4 6 rib pulley

[Eagle2000GT]

There are a lot of variable in predictiing boost and I'm running a 3 core intercooler instead of a 2 core but I would think a 3.6" pulley would put you around 9-10 psi. A 3.5 would be somewhere around 10-11 psi. I recommend the 3.6 for a daily driver. You can go 3.5 or 3.4 if you really want to push it.

House of Boost sells pulleys for $90. House of Boost: Corvette parts, Z06 parts, Camaro parts, GTO parts, G8 parts, Trailblazer SS parts, LS1 parts, LS2 parts, LS3 parts, LS6 parts, LS7 parts, LS9 parts, LSX parts, Mustang parts

P.S. It takes an impact wrench to get the pulley off.

[Shaun03GT]

Tom, wouldn't a 3.4 pulley be good for a 2 core intercooler since it wont flow as much cfm as a 3 core? I figure a 3.6 with a 3 core should be 10psi. And a 3.4 with a 2 core should be 10psi.

Correct me If im wrong