Underdrive Pulley Power Kit

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"Free" power.

Slightly reducing the crankshaft pulley size reduces parasitic loss through rotational inertia directly on the crank.

Optimised for the street.

The reduced diameter was selected as a balance between power, auxiliary functions and coolant temperatures.

Machined from billet aluminum.

The pulleys are machined from 6061 aluminum billet and anodized in a black finish.

Sold as a kit.

It includes new OE accessory belts and hardware.
Build Journal: mechanical program
A little something something.

As we waited for parts during the upgrade and refresh to the S85-002, I decided to test an unoften discussed "free" upgrade.

Some say underdrive pulleys make a difference, others say they didn't feel a thing.

As part of my Special Series on the S85-002, I'll chat on the underdrive pulley theory, the kit I picked and my impressions.

Cheers,
- Matt / @m3_epoustouflant

Spec your kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit
S65/S85 Underdrive Pulley Kit

391019

S65/S85 Underdrive Pulley Kit

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Specifications: 

  • CNC machined 6061 aluminum billet
  • Anodized in black finish
  • Optimized diameter for street compromise between power and auxiliary functions. 
  • Reduces parasitic loss on the crankshaft
  • Advertised gains of up to 22 HP and 21 Ft/lbs Torque
  • There are slight variances for the S65 6spd and DCT.
  • Comes with Continental and Gates accessory belts and installation hardware
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