The Dodge SRT-4 remains a benchmark in the front-wheel-drive turbo world. Its light chassis, peppy 2.4L engine, and factory Mitsubishi TD05HR turbocharger made it an instant hit with tuners. But stock turbo spools quickly run out of steam, and the 2.4L bottom end has a fatigue limit that serious power seekers must respect. That is where the AMS 2.8L stroker kit comes in. Designed to literally give your 2.4L more breathing room and displacement, this kit, paired with the right tuning strategies, can push your SRT-4 well past a 50-horsepower gain at the wheels. This article covers exactly how to achieve that number—from selecting the right supporting hardware to dialing in the engine management.

What the AMS 2.8L Kit Actually Delivers

The AMS 2.8L stroker kit replaces the factory 2.4L rotating assembly with a forged crank, longer rods, and custom pistons that bump displacement to 2.8 liters. The extra displacement gives the engine a larger swept volume, which increases torque across the entire curve and lets a smaller turbo spool harder than it would on a 2.4L. More important, the forged internals raise the rev limit and the maximum cylinder pressure the bottom end can tolerate. That directly unlocks the potential for much higher boost pressures and safer operation at elevated power levels.

Key components in the kit include:

  • 4340 forged steel crankshaft with increased stroke
  • Forged connecting rods (often H-beam or I-beam) rated for 500+ hp
  • Custom-forged pistons with proper ring groove positions for 2.8L geometry
  • Main and rod bearings matched to the new rotating mass

This package is a direct bolt-in for the SRT-4 block—no sleeving, no deck plate. The result is a bottom end that can comfortably support 500–600 whp with the right tuning, but even a moderate 50 hp gain is easily attained at much lower stress levels.

Pre-Tuning Checklist: Don’t Skip These Steps

Before you even think about adjusting fuel maps or ignition timing, you must verify that the rest of the car is ready for the extra power. A 50 hp gain may sound modest compared to the kit’s potential, but it still requires a balanced approach. Neglecting any of the following will lead to knock, overheating, or drivetrain failure.

Engine Health and Break-In

After installing the AMS 2.8L kit, you must follow the piston ring seating procedure exactly. The forged rings require a specific heat cycle and short break-in period (usually 500–800 miles with light to moderate throttle, no sustained boost). Use a high-zinc break-in oil and change it after the first hour of runtime to remove any metallic debris.

Supporting Airflow Mods

The stock intake, intercooler, and throttle body are restrictive for the 2.8L’s increased demand. Invest in a cold-air intake with a large filter, a bar-and-plate front-mount intercooler (the stock side-mount will heat-soak immediately), and a 65 mm or larger throttle body. If you plan to push beyond 350 whp, consider porting the intake manifold or upgrading to a sheet-metal unit. AMS Performance offers a full line of air-to-air intercoolers designed for the SRT-4 that complement the stroker kit perfectly.

Fuel System Readiness

With 2.8 liters of displacement and higher boost, the factory fuel pump and injectors will run out of headroom quickly. At a minimum, install 750 cc or larger injectors (e.g., Bosch EV14), a 255 LPH or 340 LPH in-tank fuel pump, and an adjustable fuel pressure regulator set to 43.5 psi base pressure. If you intend to run E85 in the future, upgrade to stainless-steel braided lines and a fuel pressure sensor for the ECU.

Engine Management Options

You cannot tune a 2.8L stroker with a simple piggyback. The fuel and ignition maps need complete rewriting to account for the different cylinder displacement and airflow. The best options are a full standalone or a reflash of the factory ECU. Standalone units like the AEM Infinity or Haltech Elite 2500 give you complete control over fuel, timing, boost by gear, launch control, and knock strategies. The factory ECU can also be reflashed via tools like DiabloSport Trinity or HP Tuners if you work with a calibrator who knows the 2.8L characteristics. HP Tuners has SRT-4 support and a large community of tuners who have experience with the AMS stroker.

Tuning Strategies for a Reliable 50+ Horsepower Gain

Achieving 50 whp reliably on a 2.8L stroker is almost too easy—the displacement alone adds 15–20 whp at the same boost pressure. But to get the full 50+ hp without damaging the engine, you need to optimize four areas: airflow, fuel delivery, ignition timing, and boost control.

Airflow Optimization at Higher RPM

The stroker engine flows more air per revolution than a 2.4L. At high RPM the turbo must support that flow without choking. A GT3582R or BorgWarner S366 sized turbo works well because the added displacement helps spool them harder than they would on a stock 2.4L. Install a 4-inch inlet tube and a 3-inch intercooler piping to minimize pressure drop. Use a blow-off valve that can hold 30+ psi (like a Tial Q or Synapse) to prevent compressor surge.

Fuel Tuning for the Larger Displacement

The fuel map must be scaled for a 2.8L engine. This means increasing the injector pulse width across the board, especially at lower RPM where volumetric efficiency is higher. Use a wideband oxygen sensor (AEM or PLX) to target 11.5:1 air-fuel ratio under heavy boost. For 91–93 octane, keep peak boost at 18–20 psi if you are aiming for a safe 350–380 whp. If you run E85, you can push 24–26 psi and still stay cool, easily exceeding 50 hp gain. Fine-tune the transient fuel tables to avoid lean spikes during throttle tip-in.

Ignition Timing: The Fine Line

The 2.8L stroker has a bigger combustion chamber volume, so it tends to be less knock-prone than a highly strung 2.4L at the same boost level. Still, ignition timing must be dialed back from the factory curve. Start with a baseline of 12–14 degrees at peak torque (around 4000 RPM) and advance to 18–20 degrees by the redline. Use a knock sensor (or factory knock monitoring via the ECU) and log each pull. E85 allows 2–4 degrees more advance than pump gas without knock. Back off timing by 0.5 degree if you see even slight knock count values—the forged rods can handle the combustion pressure, but detonation will still crack ring lands.

Boost Control Strategy

The stroker loves boost, but the way you get there matters. Use a boost controller (manual or electronic) to ramp in boost smoothly. An abrupt application of 20+ psi on a 2.8L can overwhelm the tires and break axles. Many SRT-4 owners use a Hallman Pro MBC or a 3-port solenoid with the ECU controlling duty cycle. Set a target of 18 psi at 3500 RPM, then taper slightly to 16 psi at redline for the best power under the curve on pump gas. For E85, start at 22 psi and hold it to redline—the extra oxygen content in the fuel will net you the 50+ hp with zero drama.

Data Logging and Dyno Tuning Approach

It is tempting to just flash a generic “2.8L tune” from the internet, but every engine has minor variations in compression ratio, fuel quality, and sensor calibration. The only way to guarantee a safe 50+ hp gain is to tune it on a dynamometer equipped with wideband O2 and knock logging. Plan on spending at least 2–3 hours of dyno time for a base tune, then another session for final trimming.

Key parameters to log:

  • Mass airflow (MAF) or calculated load
  • Engine coolant temperature (keep below 205°F at full throttle)
  • Intake air temperature (IAT) after intercooler – should stay within 20°F of ambient
  • Knock level per cylinder (if ECU supports it)
  • Fuel pressure (must remain steady under high load)
  • Boost pressure vs. RPM curve

A typical dyno sheet for a 2.8L kit with stock turbo at 18 psi shows a peak of about 320–340 whp and 360–380 lb-ft of torque. Upgrading to a GT3582R at 20 psi on E85 can produce 400+ whp. That is a 100+ hp gain over a stock SRT-4, well above the 50 hp goal. Real-world dyno threads on SRTForums show that even conservative tunes deliver 50–70 whp gains with excellent reliability.

Keeping the Drive Train and Cooling in Check

Adding 50+ hp to a front-wheel-drive car places new stress on the transmission, axles, and cooling system. The SRT-4’s T850 transmission is robust, but the differential pins and axles can fail under repeated hard launches. At minimum, upgrade to hardened axle shafts (DSS or Stage 3) and install a Quaife or Wavetrac limited-slip differential. For cooling, use a high-flow water pump, a 160°F thermostat, and an electric fan shroud to keep engine temps in check during prolonged pulls. The oil cooler that came on some SRT-4s should be upgraded to a larger setrab or similar unit, especially if you plan to track the car.

Conclusion: Realizing the Promise of the AMS 2.8L Kit

The AMS 2.8L kit transforms the SRT-4 from a fun street car into a seriously potent machine. By adding 0.4 liters of displacement and stronger internals, you create the foundation for a rock-solid 50+ horsepower gain with relatively modest boost levels. The key is not to rush the process: break in the engine properly, upgrade the airflow and fuel systems, and commit to a custom tune using a quality standalone or reflash. A well-executed 2.8L setup delivers drivability, reliability, and power that will surprise drivers of much more expensive cars. Whether you keep it at a conservative 18 psi on pump gas or push into the 400 whp range with E85, the AMS 2.8L kit paired with the tuning strategies covered here will maximize your SRT-4’s potential safely and consistently.