The JLT 2.80 Pulley Upgrade: Unlocking 700+ Horsepower from Your Hellcat

For Dodge Hellcat owners who crave more than the factory 707 horsepower, the JLT 2.80 supercharger pulley upgrade is one of the most cost-effective and impactful modifications available. By spinning the supercharger faster, this simple swap can push output well beyond 700 wheel horsepower when combined with proper supporting modifications. This guide covers everything you need to know—from how the pulley works and what gains to expect, to installation steps, tuning requirements, and real-world results.

How the JLT 2.80 Pulley Works

The heart of the Hellcat’s power is its 2.4-liter IHI supercharger, which force-feeds air into the 6.2L Hemi V8. The supercharger is driven by a belt connected to the crankshaft via a pulley. Factory-equipped 2015–2023 Hellcats (including Charger, Challenger, Durango, and Jeep Trackhawk) use a 2.72-inch pulley on the supercharger snout. The JLT 2.80 pulley replaces that factory pulley with a slightly smaller diameter—2.80 inches versus the stock 2.72. While 0.08 inches may sound trivial, the change dramatically increases supercharger speed. A smaller pulley forces the supercharger to spin faster at any given engine RPM, which raises boost pressure significantly. Typical Hellcat boost jumps from about 11.6 psi to around 13–14 psi with the JLT 2.80 pulley alone, and with proper tuning, those extra pounds of boost translate directly into 50–80 horsepower at the wheels.

The JLT pulley is CNC-machined from 6061-T6 billet aluminum and features a precision bore for a vibration-free fit. It includes a replaceable press-in hub that accepts the factory supercharger snout coupler, making installation straightforward. The pulley is also 10-rib compatible, handling the increased belt load without slipping.

Why 2.80 Inches? The Sweet Spot

JLT offers several pulley sizes for the Hellcat: 2.85, 2.80, 2.75, 2.70, and even smaller. The 2.80 is widely considered the safe, street-friendly option. It provides a substantial power increase while remaining within the blower’s safe RPM limit and without requiring immediate fuel system upgrades like injectors or a BAP (boost-a-pump). Larger pulleys (smaller diameters) such as 2.70 generate more boost but demand more comprehensive supporting mods (e.g., lower intake temps, upgraded fuel system, colder plugs, and careful tuning). The 2.80 hits a balance: enough boost to break 700 whp with a tune, but still conservative enough for daily driving on pump gas (93 octane).

Expected Horsepower and Torque Gains

Real-world dyno results from Hellcat owners show that the JLT 2.80 pulley alone—with no other changes—typically adds 30–50 whp. However, the true potential is realized when combined with a custom tune. A properly tuned Hellcat with the 2.80 pulley often produces:

  • 650–690 wheel horsepower on 93-octane pump gas (stock air intake and exhaust)
  • 710+ wheel horsepower with a cold air intake (like JLT’s own CAI) and cat-back exhaust
  • 730+ whp on E85 (requires injectors and fuel system upgrades)
  • Torque figures usually climb to 650–680 lb-ft at the wheels

For context, a stock Hellcat typically dynos at 650–660 whp. So the pulley + tune package can yield a net gain of 50–80 whp, easily pushing the car past the 700 whp threshold. Quarter-mile times improve by 0.3–0.5 seconds, often landing in the 10.5–10.7-second range on street tires.

Installation Process: Step-by-Step

Installing the JLT 2.80 pulley is a moderate DIY job if you have basic mechanical skills and tools. However, if you’re uncomfortable working near the supercharger snout, a shop can complete the swap in about two hours. Here’s an expanded look at the process:

Tools and Parts Needed

  • JLT 2.80 pulley kit (includes pulley, press-in hub, and instructions)
  • Pulley removal tool (JLT recommends their own or a standard three-jaw puller)
  • Torque wrench (capable of 25–30 ft-lb)
  • Socket set (10mm, 13mm, 15mm, 18mm)
  • Breaker bar
  • Thread locker (Loctite 242) for the pulley bolt
  • Safety glasses and gloves

Step 1: Disconnect Battery and Remove Belt

Disconnect the negative battery terminal to prevent accidental starting. Then, using a 15mm socket on the tensioner pulley, rotate the tensioner clockwise to relieve belt tension, and slide the serpentine belt off the supercharger pulley. It’s wise to mark the belt routing or take a photo for reference.

Step 2: Remove Factory Pulley

Using a pulley removal tool (commonly a three-jaw puller), place the jaws behind the factory pulley. Tighten the puller’s center bolt against the supercharger snout shaft until the pulley pops free. Be careful not to damage the snout. The factory pulley is pressed on and will require steady force; it may pop loudly when it releases. Remove the retaining bolt (if present) first—on some Hellcat models there is a single 18mm bolt securing the pulley to the snout.

Step 3: Install JLT Pulley

Clean the supercharger snout shaft with brake cleaner to remove any debris. Apply a small amount of anti-seize or moly grease to the snout splines. Press the JLT pulley onto the snout by hand as far as possible, then use the included installation tool (or a large socket and mallet) to seat it fully. Ensure the pulley is flush against the snout face. Install the retaining bolt (usually a 10mm Allen or hex) and torque to 25–30 ft-lb with Loctite 242.

Step 4: Reinstall Belt and Reconnect Battery

Route the serpentine belt over all pulleys according to the routing diagram. Use the tensioner again to slip the belt onto the supercharger pulley. Spin the engine over by hand (using a socket on the crankshaft bolt) to ensure the belt tracks properly. Reconnect the battery.

Step 5: Check for Leaks and Start-Up

Start the engine and let it idle for a few minutes. Listen for any unusual noises from the supercharger area. Check for belt misalignment or rubbing. A healthy supercharger should whine louder than stock—this is normal and expected. Once confident, take a short test drive to verify smooth operation.

Note: Some owners also choose to replace the supercharger oil during this service, as the job is easier with the pulley off.

Tuning: Why It’s Non-Negotiable

The JLT 2.80 pulley increases boost by roughly 2–3 psi. Without recalibrating the engine’s air/fuel ratio and ignition timing, the extra airflow can cause lean conditions, detonation, and potential engine damage. A custom tune from a reputable calibrator (e.g., Dusterhoff, HP Tuners, Diablosport) is mandatory. The tuner will adjust:

  • Fuel tables: Enrich the mixture to prevent lean spikes under boost.
  • Spark timing: Reduce timing slightly to avoid knock, especially on pump gas.
  • Boost control: Optionally raise the rev limiter or adjust throttle mapping.
  • Transmission: Firm up shift points and increase line pressure for the ZF 8HP (8-speed auto).

A typical pulley+tune package costs $400–$600 for the tune (plus the pulley kit, around $250). Some tuners offer remote tuning via e-mail or data logging. If you run E85, a separate flex-fuel tune with larger injectors is required.

Supporting Modifications for Maximum Power

To fully exploit the JLT 2.80 pulley, consider pairing it with these complementary upgrades:

  • Cold Air Intake: A larger intake like JLT’s own system reduces inlet restriction and lowers IATs (intake air temperatures), adding 10–15 whp.
  • Cat-Back Exhaust or Axle-Back: Reduces backpressure; adds a few horsepower and a more aggressive sound.
  • Heat Exchanger Upgrade: An aftermarket supercharger intercooler heat exchanger (e.g., from AFE or Mishimoto) keeps charge air cooler, sustaining power on hot days.
  • Spark Plugs: Colder heat-range plugs (NGK 6510 or equivalent) prevent pre-ignition under higher boost.
  • Fuel System: For E85 or pump gas above 15 psi, consider a Boost-A-Pump or larger injectors (e.g., 1000cc).

Comparison with Other Pulley Sizes

Hellcat owners often debate between the 2.80 and smaller pulleys. Here’s a quick comparison:

  • JLT 2.85: Gains 20–30 whp; very safe but less dramatic. Good for 93-octane without tune (though tuning still recommended).
  • JLT 2.80 (sweet spot): ~50–80 whp gain; requires tune; ideal for pump gas and street use.
  • JLT 2.70 or 2.60: 80–120+ whp but require E85, fuel system, and often a lower thermostat. More aggressive, with increased supercharger heat and wear.

The 2.80 strikes the best balance for daily-driven Hellcats that see occasional track use.

Real-World Owner Experiences

Online forums (e.g., Hellcat.org, ChallengerTalk) are filled with positive feedback. One owner reports: “Installed the JLT 2.80 with a Dusterhoff tune. Car pulls like a freight train. Dyno’d at 710 whp on 93. No issues after 10k miles.” Another notes: “The whine is addictive. But get a tune—don’t skip it. I had to also upgrade my heat exchanger because I was getting heat soak after hard pulls.” Most agree that installation is straightforward and the power gain is immediately noticeable.

Potential Drawbacks and Considerations

Before purchasing, weigh these factors:

  • Warranty: Any pulley swap can void the supercharger and engine warranty on new vehicles. Check with your dealer.
  • Heat: More boost means higher supercharger discharge temperatures. A heat exchanger upgrade is strongly recommended if you’re in a hot climate or plan to track the car.
  • Belt Slippage: If the belt is old or the tensioner weak, it may slip under hard acceleration. Replace the belt if it’s worn, and consider a shorter belt (gates part #K081280HD) if needed.
  • Emissions: In some states, a pulley change may require a tune that could affect smog testing (though a pulley alone often passes visual inspection).
  • Insurance: Notify your insurer of modifications—failure to do so could affect claims.

Cost Breakdown

Typical costs for the JLT 2.80 pulley upgrade:

  • JLT 2.80 pulley kit: $250–$300
  • Custom tune (mail-order or dyno): $400–$700
  • Installation labor (if shop): $200–$300
  • Optional: CAI ($300–$400), heat exchanger ($500–$800), spark plugs ($40)

Total for base pulley + tune: ~$650–$1,000. That’s a remarkable price-per-horsepower ratio (about $10–$15 per wheel horsepower).

Maintenance After Upgrade

Once installed, routine maintenance stays nearly identical. However, because the supercharger is spinning faster, it’s wise to:

  • Inspect the belt every oil change for cracks or glazing.
  • Monitor supercharger oil level (change every 30,000 miles or when you replace the pulley).
  • Log IATs and boost with a scan tool occasionally to ensure the tune is safe.
  • Use top-tier 93 octane fuel (or higher) to minimize knock risk.

Alternatives to JLT 2.80 Pulley

Other manufacturers produce similar pulleys (e.g., Metco, RIPP, ATI) but JLT is renowned for quality and fit. If you want more power without a pulley swap, consider a smaller supercharger snout pulley from RIPP Superchargers or a ported supercharger upgrade from Jumper Cable (Example Link). But for the street, the JLT 2.80 remains a top choice.

Final Verdict

The JLT 2.80 pulley upgrade is one of the smartest modifications you can make to a Hellcat. It delivers a tangible power increase—often enough to reach or exceed 700 wheel horsepower—without the complexity or cost of a full supercharger swap. When paired with a professional tune and basic supporting mods like a CAI and heat exchanger, the result is a car that feels dramatically quicker from a roll or at the drag strip. Just remember: never run the car with the pulley alone—tuning is essential for reliability. If you’re ready to turn your Hellcat into a true 700+ HP monster, the JLT 2.80 pulley is the place to start.

For more information, check JLT’s official product page or forums like Hellcat.org and Challenger Talk for community dyno sheets and owner feedback.