Buyer's GuideApril 18, 2026

Supercharger Lid and Blower Pulley Upgrades: What They Do and What They Cost

A smaller blower pulley or ported lid is the first and most cost-effective upgrade for any Hellcat or Redeye.

The Supercharger System Basics

The Hellcat's 2.4L Roots-type supercharger is belt-driven off the crankshaft. The ratio of the crank pulley diameter to the blower pulley diameter determines how fast the supercharger spins. Faster spin = more boost.

Lid Porting

The supercharger lid houses the throttle body and the inlet to the blower rotors. Factory lids have casting restrictions that limit airflow.

What porting does: Enlarges and smooths the inlet passages, reducing restriction and improving mass flow. A ported lid typically adds 20–40 hp on a stock-boost Hellcat without changing boost levels.

Who does it: STS Turbo, SHR, Lethal Performance, and others offer ported Hellcat lids.

Cost: $400–700 for the ported lid exchange service. Worth doing before spending on pulleys.

Smaller Blower Pulley (Underdrive Pulley)

Replacing the 2.65" factory blower pulley with a smaller pulley spins the blower faster, generating more boost.

Common upgrades:

  • 2.45" pulley: ~1–1.5 psi more boost, 30–50 hp gain
  • 2.40" pulley: ~1.5–2 psi more boost, 40–60 hp gain
  • 2.10" pulley (aggressive): Requires upgraded fuel system and tune, significant cooling demands

Important: Pulley upgrades require a tune. Running more boost without recalibrating fuel and ignition causes detonation.

The Lid + Pulley Combo

The most popular Hellcat first step: ported lid + 2.45" pulley + E85 tune.

Expected gains on a stock Hellcat:

  • From 707 hp at the crank to approximately 620–650 whp
  • Quarter mile improvement: typically 0.3–0.5 seconds off the stock ET

Supporting Mods Required

  • Upgraded spark plugs (one heat range colder, 0.035" gap)
  • Tune calibrated for the new boost level
  • Verify fuel pump can support increased demand
  • Consider heat exchanger coolant upgrade for sustained use