Originally Posted by KraftWerks

Hello All,

CJ here! I want to apologize ahead of time for the length of the post!

I've been seeing quite a few threads pop up recently, undoubtedly due to @Moddiction and their kick-ass group-buy they offered which moved a TON of kits and I believe is still going.
With that said, I want to make sure that everyone knows that if they have ANY questions or concerns with the kit, whether it's before or after the purchase, I am here to help where I can.

I can be contacted via PM here or via Direct Email → cjweidl@group-a-eng.com ← I'll try my absolute best to respond within 24 hours via email / pm, much faster if I can help it but especially during this 'Tax Baller' season, you can imagine all of our bandwidth here is pretty soaked up.

I am working with my team here to finalize the sets of revised instructions to include the new drive-system information as well as the updated brackets to be mounted on both sides of the cylinder head, alleviating that center mounted piece off of those 2 mounting points on the front of the motor.

This is the drive-system as it is currently with the kits as well as the drop down size options;

Here is the standard formula to find out the impeller speed:
Impeller RPM = RPM Engine MAX x Crank Pulley Dia. x Rotrex Ratio / Supercharger Pulley Dia.
For Example: 9350 (RPM ENGINE MAX AP1) x 128 (Crank Pulley) x 7.50 (C38 Ratio) / 100 (Supercharger Pulley) = 89,760 RPM @ Impeller.

For those with some custom setup or an RPM that isn't noted, use this:
Pulley Dia. Supercharger = RPM Engine MAX x Crank Pulley Dia. x Rotrex Ratio / Impeller RPM
For Example: 9350 (RPM Engine Max AP1) x 128 (Crank Pulley) x 7.50 (C38 Ratio) / 90,000 (C38 Max Impeller) = 99.73 → 100

AP1 Comes with 128mm Crank + 100mm S/C Pulley for 9350Rpm Redline @ Approx 12.5psi → 89,760 @ Impeller
Option 1. AP1 128mm Crank + 95mm S/C Pulley for 8900Rpm Redline @ Approx 14.5psi → 89,937 @ Impeller
Option 2. AP1 128mm Crank + 90mm S/C Pulley for 8450Rpm Redline @ Approx 16.5psi → 90,133 @ Impeller


AP2 Comes with 128mm Crank + 90mm S/C Pulley for 8400Rpm Redline @ Approx 13psi → 89,600 @ Impeller
Option 1. AP2 128mm Crank + 85mm S/C Pulley for 8000Rpm Redline @ Approx 14.5psi → 90,353 @ Impeller
Option 2. AP2 128mm Crank + 80mm S/C Pulley for 7500Rpm Redline @ Approx 16.5psi → 90,000 @ Impeller

These pulleys are available directly for $89.99 MSRP and any of our Authorized Dealers will have access to them as well, just most likely not IMMEDIATELY In-Stock.

*Note: These RPM Figures are what the CHARGER is spec'd to go to, not necessarily where the car may be going to, this is more towards the standard pulley options*

Note, some of the 'high-boost' options will slightly overspin the supercharger. You'll also find that some users are seeing much higher boost than what our approximate boost figures were.
If the system is congested at all meaning, stock header, oe cat, stock or smaller exhaust, etc. the boost figures will be higher. It's certainly not impossible to see the 20+ psi on the setup but could be making the same power as a car at 16lbs, just with more free-flowing parts. The same is to be said about any forced induction setup whether it be turbo or supercharger.

If you have a kit with the OLD Drive System Setup (100mm Crank, 80 or 70mm S/C), and the older side-mounting brackets AND you are the original owner of the kit, PLEASE CONTACT me so I can get you upgraded to the proper equipment. If you are a second-hand owner, we can still work out a discounted value for the upgrade! ← I have attached the blown-up drawings of the revised drive-system as well as the bracket upgrade so the information is consolidated here as opposed to having some of the awesome users continuing to share with each new thread that posts up.


If there's anything left out, please let me know!

If ANYONE has CONSTRUCTIVE input regarding the instructions and is willing to work with me by outlining specific points for me to potentially incorporate into the instructions to make things easier and more convenient for everyone, please reserve that comment STRICTLY for email. We can discuss those changes outside of the boards.

Originally Posted by michaelnyden

Lets start a thread to keep all upgrades and options for the new C38 Kraftwerks supercharger kit.

From my understanding as explained to me by a vendor on here, the C38 can spin to maximum of 90K rpm. The kit comes with a 90 or 100mm pulley and has these options as upgrades from Kraftwerks:

AP1 Comes with 128mm Crank + 100mm S/C Pulley for 9150Rpm Redline @ 12.5psi
Option 1. AP1 128mm Crank + 95mm S/C Pulley for 8900Rpm Redline @ Approx 14.5Psi
Option 2. AP1 128mm Crank + 90mm S/C Pulley for 8450Rpm Redline @Approx 16.5Psi


AP2 Comes with 128mm Crank + 90mm S/C Pulley for 8200Rpm Redline @ 13psi
Option 1. AP2 128mm Crank + 85mm S/C Pulley for 8000Rpm Redline @ Approx 14.5Psi
Option 2. AP2 128mm Crank + 80mm S/C Pulley for 7600Rpm Redline @Approx 16.5Psi

So obviously at these designated redlines, the blower is at ~90K RPM. At what PSI/pulley do you think it would be wise to upgrade to their larger BOV option? I assume if stilal taking the AP1 to the fctory 9K redline, the 8900 (95mm pulley) would still be safe? Can a math guru help me out with the calculations on blower/impeller speed? Maybe we can make a chart of input shaft, engine rpm, and impeller speed. The drive ratio on the C38 is 1:7.5

Originally Posted by schhim

When changing pulleys, is it recommended to use new allen bolts? If so, how can we obtain these bolts?