HKS Supercharger Pulley Upgrade Kit - 2013+ FR-S / BRZ / 86

Supercharger Pulley Upgrade Kit for the HKS GT2 Supercharger System

The HKS Supercharger Pulley Upgrade Kit for the 2013+ FR-S, BRZ, and 86 is a pulley size change for existing HKS GT2 supercharger system owners who want to increase boost pressure beyond the stock pulley configuration. Changing the supercharger drive pulley ratio increases the supercharger speed relative to engine RPM, which increases boost pressure and charge volume. The most effective way to extract additional power from an already-supercharged application.

Specs & Highlights

• Pulley upgrade for HKS GT2 supercharger system
• Increases supercharger speed and boost pressure
• Required for power levels beyond stock GT2 pulley configuration
• Precision machined pulley
• Requires recalibration or retune after installation
• Fitment: 2013+ Scion FR-S / Subaru BRZ / Toyota 86 with HKS GT2 supercharger

15-18% Speed Increase, 9-11 psi Boost Target

The upgrade pulley reduces the supercharger drive pulley diameter from the stock ratio, increasing rotor speed by approximately 15–18% depending on the specific pulley selected. This raises boost pressure from the standard 7–8 psi to approximately 9–11 psi. Power output on a properly tuned car increases from approximately 228–235 whp to approximately 255–270 whp. Supporting modifications, upgraded fuel injectors, a tune accommodating the higher boost, and confirmed oil and cooling system health, are required before installing the pulley upgrade.

Pulley Work Requires a Retune

Pulley upgrades on supercharged applications are a well-understood way to increase boost, but they require corresponding changes to the tune to take advantage of the additional pressure. Running a smaller pulley (faster supercharger) on the original tune risks running the engine on an air/fuel mixture calibrated for lower boost. A professional retune is required when changing the pulley ratio.

Supporting Modifications Before the Pulley

This kit requires an existing HKS GT2 Supercharger System installation. It is not compatible with other supercharger systems. The pulley dimensions are specific to the GT2 system's drive architecture.

The FT Breakdown

The pulley upgrade kit is for GT2 system owners who have maximized the stock pulley configuration and want more. It is a power-seeking part that comes with real requirements: a proper tune, possibly upgraded fuel system components depending on your target power level, and an understanding of what higher boost pressure asks of the rest of the drivetrain. The 15–18% supercharger speed increase from the upgraded pulley is not a trivial performance delta — going from 228 whp to 255–270 whp on a properly supported tune is a 12–18% power increase on a car that weighs approximately 1,250 kg. On the track that difference is felt in every corner exit. The requirement for a retune is not optional and not a formality; it is engineering reality.