MAIN FEATURES OF THE KIT:

• Billet aluminum alternator pulley

• BOSCH -type replaces BMW part No. 12311432988 or 12311703736 or 12311726139 found on M43 / M44 / M50 / M52 / S50 engines (pulley height 41mm)

• VALEO -type replaces BMW part No. 12311713945 or 12311436636 or 12311703735 or 12311403026 found on M43 / M50 / M52 / M54 / S50 / S52 engines (pulley height 49mm)

• Increases alternator life

• Reduces horsepower losses

• Longer serpentine belt might be required!

• COMES WITH MRT ENGINEERING DECALS
  
  

WHY DO YOU NEED ONE?

If you're building a high revving track / drifting / rally engine, here's a simple and effective solution to increase alternator life and reduce horsepower losses. This billet aluminum alternator pulley has 35% underdrive ratio compared to original pulley, drive ratio will be changed from 3:1 to 2:1.

DOES IT FIT MY CAR?

The kit can be used in most BMW M43 / M44 / M50 / M52 / M52TU / M54 / S50 / S52 engines equipped with Bosch or Valeo alternator. See reference pictures of alternator and pulley type.

IS IT EASY TO INSTALL?

Bosch -type drawing, PDF

Valeo -type drawing, PDF

No special tools needed, part will directly bolt-on. Loctite or similar thread or shaft lock adhesive is recommended on installation of the pulley.

If you need any further info please contact us!

HOW ABOUT THE LIFETIME AND SERVICE OF THE KIT?

The kit does not need service while in use, always use Loctite on bolts and screws that might become loose. The kits have been proven on street and track applications by many of our customers. We're constantly doing R&D to make the kits even better, all improvements are based on customer feedback which is very important to us. Any of the spare parts can be also bought separately from us.

We want to keep our customers 100% happy thus we're only using the best materials and manufacturing processes available. Pulley is CNC machined out of AW-6082 aluminum billet.