On the dyno the belt driving the super charger and water pump starts to slip at 950ish HP. Adding the alternator and A/C compressor would only make that situation worst. After a lot of thought, I decided the best approach would be to mount a custom 6-groove pulley to the face of the crankshaft damper and run a second serpintine system. This is going to make things very tight and require custom brackets for both the alternator and the A/C compressor, but it seems like the best approach -- time will tell.
I spent a lot of time searching for "custom billet pulley" and found lots of companies making beautiful pulleys, but all that I spoke with are focused on products and not one-off pulleys. Anyone with a CNC lathe can make one, but I wasn't sure of the profile of the ribs. I eventually found ASP Racing and they were great to deal with.
The diameter was optimized for the A/C compressor because that A/C compressor doesn't work well at low RPM and running it too fast will damage it. In addition, unlike the pulley on the alternator which can be easily changed, the compressor pulley has an integral clutch which means that it can't be changed.
Here are the final specs:
- 6 grooves
- 6-1/4” diameter
- Concentric locating flange machined to fit inside the damper’s 2.050 ID.
- 3 bolt holes for 3/8” bolts on a 3.2” hole pattern
- Clear anodized machined finish
The next step is to pull the engine and design the custom brackets and serpentine system.