This solution was originally developed on the HyperMiata time attack car, which uses a Rotrex C38 on its LFX V6 engine. Early tuning of the system left us wanting to know exactly what RPM the supercharger was spinning at instead of just basing things off a theoretical calculated speed derived from engine RPM.

Having true supercharger RPM data monitored and logged by the ECU allows you to identify belt slip, know where you are on the compressor’s efficiency map, make better informed decisions about pulley size changes, and more.

To accomplish this, we use a custom pulley adapter that is CNC machined from 6061 aluminum which makes it possible to mount a Haltech split collar to the supercharger pulley. This split collar is typically used for driveshaft RPM in drag cars. It has 8 rare earth magnets embedded in it, which provide a strong square wave signal to a hall effect sensor – far better than a tone ring. The hall effect sensor we supply is a Haltech GT101 Style High Frequency Hall Effect Sensor. You can get just the adapter and split collar from us if you wish to use your own different hall effect sensor, just be sure that it is a suitable type that can provide high resolution.

Installation on the HyperMiata:

Adapter:

• CNC Machined 6061-T6 Aluminum
• Counter-sunk holes for precise centering. Tighten these like a lug nut; evenly and in a cross-pattern
• Includes 6 x M6 countersunk bolts

Split Collar:

• Haltech aluminum split collar
• 8 embedded rare earth magnets
• Includes bolts and allen key to fasten the two halves together

Hall Effect Sensor:

• Haltech GT101 Style High Frequency 3-wire sensor
• Includes Deutsch DTM-3 male and female connectors, with contacts
• Includes instructions for wiring, sensor setup, and dimensions
• *You must make your own bracket to mount the hall effect sensor* Recommended gap is ~1.5 mm to the collar

The supplied M6 hardware for the pulley adapter is the correct length for use with Kraftwerks 6 rib v-belt supercharger pulleys (which are ~12mm thick at the bolt holes), but this adapter can be used with any other Rotrex pulleys with just a different length bolt as needed if your pulley is a different thickness. Be sure to use countersunk bolts so the adapter self-centers as you tighten the bolts.