The 6.4L HEMI V8 found in Dodge Challenger models like the Scat Pack and SRT 392 is a naturally aspirated powerhouse, delivering stout horsepower and torque from the factory. However, for enthusiasts who crave more—whether for drag strip domination, road course aggression, or sheer street thrill—adding forced induction through a turbo kit transforms this already impressive engine into a serious performer. Among the aftermarket options, MRT Performance has carved a reputation for engineering turbo systems that balance power gains with reliability.

Choosing the right MRT Performance turbo kit for your 6.4L HEMI Challenger is not a one-size-fits-all decision. It requires matching the kit's capabilities to your specific goals, driving habits, and preparation for supporting modifications. This guide breaks down every critical aspect to help you make an informed selection that delivers the performance you want without unnecessary headaches.

Understanding Turbocharging for the 6.4L HEMI

Forced induction via a turbocharger uses exhaust gases to spin a turbine, which compresses incoming air and forces it into the engine's cylinders. This allows the engine to burn more fuel, creating significantly more horsepower and torque than natural aspiration alone. The 6.4L HEMI responds exceptionally well to forced induction due to its robust cylinder heads, forged steel crank, and decent rod and piston strength—though supporting upgrades are still required for higher boost levels.

MRT Performance designs their kits specifically for the HEMI platform, taking into account engine bay layout, accessory placement, and thermal dynamics. Their systems typically include the turbocharger(s), exhaust manifolds or headers, intercooler, wastegate, blow-off valve, piping, and necessary hardware. Understanding the fundamental benefits and challenges of turbocharging will guide your kit choice.

Benefits of Turbocharging a 6.4L HEMI

  • Massive Power Gains: Even a conservative single-turbo setup can add 150–250 wheel horsepower, while aggressive twin-turbo builds can push well beyond 1,000 horsepower.
  • Torque Curve Flexibility: Turbos can be sized to deliver a broad, flat torque curve ideal for street driving or peaked for top-end track performance.
  • Fuel Efficiency Potential: When not in boost, a turbo engine can be more efficient than a high-compression naturally aspirated engine, though this is often secondary in performance builds.

Challenges to Address

  • Heat Management: Forced induction generates significantly more underhood heat. Adequate cooling, heat shielding, and thermal barriers are essential for reliability.
  • Engine Internals: The factory 6.4L pistons and rods are strong but have limits. Boost levels above 8–10 psi (or power over ~700 wheel horsepower) often require forged internal components.
  • Fuel System Demands: The stock fuel injectors and pump may not supply enough fuel for boosted operation. Upgraded fuel delivery is non-negotiable for safe high-power tuning.

Factors to Consider When Choosing a Turbo Kit

Every build is a compromise between performance, cost, drivability, and reliability. Before shopping for an MRT Performance turbo kit, assess the following dimensions honestly.

Power Goals

Define your horsepower target early. Are you aiming for a modest daily-driver 600 wheel horsepower, a competitive track-capable 800 wheel horsepower, or an all-out 1,000+ wheel horsepower monster? MRT’s kits are often classified by power ranges, so knowing your goal directs you to the appropriate stage.

A lower power goal (500–650 wheel horsepower) can often be achieved with a stock internal engine, a mid-frame single turbo, and basic supporting mods. Higher targets require larger turbochargers, upgraded fuel systems, and often internal engine reinforcement. Be realistic about what you want to use the car for—overbuilding can waste money, underbuilding can lead to disappointment or failure.

Driving Style

How you intend to drive the Challenger heavily influences turbo selection:

  • Daily Street Driving: A kit with a smaller, quicker-spooling turbo (e.g., a 76mm or smaller single or small twins) will give you punchy low-end torque and responsive throttle. Lag is minimized, and drivability remains pleasant.
  • Drag Racing: A larger turbo that huffs air at high RPM delivers peak horsepower in the upper half of the rev range. Some lag can be tolerated if the car is mostly used for passes.
  • Road Course / Track Days: Heat management and sustained power become critical. Twin-turbo setups or large single turbos with robust intercooling and oil cooling are preferred to prevent heat soak over long sessions.

Budget

An MRT Performance turbo kit itself is a significant investment, but the total cost of a forced induction build includes much more. Be prepared to spend on:

  • Kit price (varies by stage, usually $5,000–$10,000+).
  • Professional installation ($2,000–$5,000 depending on complexity and location).
  • Tuning ($500–$1,500 for a custom dyno tune or remote calibration).
  • Supporting modifications (fuel system, cooling, exhaust, possibly internals) – easily another $3,000–$8,000.

Setting a realistic total budget—not just the kit price—prevents ending up with a turbo kit sitting in the garage because you can't afford the rest.

Installation

Turbo system installation is a major undertaking. You must decide whether to perform the work yourself or hire a professional shop.

  • DIY Installation: Requires advanced mechanical skills, a full set of tools (including torque wrenches, special sockets, possibly a lift), and significant time—plan for 40–80 hours if you're experienced. You also need the ability to diagnose and fix fitment issues.
  • Professional Installation: Eliminates guesswork and ensures proper fitment, routing, and clearances. Shops experienced with MRT kits can often complete the job in 2–4 days. Factor labor costs into your budget.

Whichever route you choose, verify that the kit includes clear instructions and that all necessary hardware (gaskets, clamps, fittings) is included. Some MRT kits require minimal fabrication; others are more involved.

Supporting Modifications

No turbo kit operates safely or effectively in isolation. The following sections detail the essential supporting upgrades that must be factored into your build plan.

MRT Performance Turbo Kit Options

MRT offers several stages for the 6.4L HEMI, each designed around a power band and complexity level. While specific part numbers and configurations can change, here is a general breakdown of their lineup.

Stage 1 Turbo Kit

Targeted at enthusiasts seeking a moderate, reliable power increase without extensive engine modifications. Stage 1 typically uses a single, relatively small turbo (e.g., 62–67mm) that spools quickly and delivers 550–650 wheel horsepower on pump gas.

  • Pros: Excellent street drivability, minimal lag, can work with stock internals and fuel system with limited boosting (conservative tune).
  • Cons: Power ceiling is lower; requires upgraded fuel system if you plan to turn up boost later.
  • Ideal For: Daily drivers, weekend warriors who want a noticeable but still tame increase.

Stage 2 Turbo Kit

A more aggressive setup, Stage 2 often uses a larger single turbo (70–76mm) or small twin-turbo configuration. Power targets range from 650 to 850 wheel horsepower. This stage generally assumes upgraded fuel injectors and pump, a boost-referenced fuel system, and possibly an intercooler upgrade.

  • Pros: Substantial top-end pull, capable of 9- or 10-second quarter-mile times with proper supporting mods.
  • Cons: More lag than Stage 1, requires careful tuning; stock internals are at risk above 750 wheel horsepower without forged pistons/rods.
  • Ideal For: Enthusiasts who want serious track capability but occasional street use.

Stage 3 Turbo Kit

Designed for maximum power output, Stage 3 kits incorporate large single turbos (80mm+) or well-matched twin turbos. Power goals exceed 850 wheel horsepower and can go well past 1,000. These kits require extensive supporting modifications: forged internals, high-flow fuel system, upgraded intercooling, and custom tuning.

  • Pros: Massive horsepower potential, pure performance.
  • Cons: High cost, significant lag, street manners compromised, requires professional build and tuning.
  • Ideal For: All-out race builds, dedicated drag cars, or show cars where peak numbers matter most.

Installation Considerations

Proper installation is the difference between a reliable, high-performance machine and a source of constant headaches. Here are critical factors to address.

Pre-Installation Engine Check

Before starting, have the engine evaluated for health: compression test, leak-down test, and oil pressure check. Boost magnifies existing weaknesses. Address any oil leaks, cooling system issues, or ignition problems first.

Cooling System Prep

Turbocharging adds immense heat. Upgrade the radiator to a high-capacity unit, add an auxiliary oil cooler, and consider a coolant expansion tank. MRT kits often include an intercooler, but you may need to upgrade to a larger air-to-air or air-to-water unit depending on your power goals.

Fuel System Preparation

Install the upgraded fuel pump and injectors before mounting the turbo system. This avoids having to wrestle with tight spaces later. Many builders also add a boost-a-pump or dedicated fuel pressure regulator. Ensure the fuel lines are compatible with the increased flow and pressure.

Professional vs. DIY – Making the Call

If you’re not comfortable fabricating custom lines, wiring sensors, or diagnosing fitment issues, pay a professional. A botched install can destroy the turbo, damage the engine, or create dangerous boost leaks. Many specialty shops that work on HEMI cars are familiar with MRT kits. Check forums like ChallengerTalk for shop recommendations.

Supporting Modifications Deep Dive

Fuel System Upgrade

A boosted engine consumes significantly more fuel. The stock 6.4L injectors and pump are inadequate beyond modest boost levels. Minimum upgrades for a Stage 1 setup include 1,000–1,200 cc/min injectors (or equivalent E85 compatibility) and a 450+ LPH in-tank fuel pump. For Stage 2 and above, switch to a return-style fuel system with a fuel pressure regulator, high-flow lines, and a surge tank or external pump.

Cooling and Heat Management

  • Intercooler: A high-flow, low-pressure-drop intercooler reduces intake air temperatures. MRT kits include one, but if you run high boost or live in a hot climate, upgrade to a larger bar-and-plate design.
  • Oil Cooler: Oil temperatures climb quickly under boost. An external oil cooler with a thermostat is a wise investment.
  • Heat Shielding: Use turbo blankets, heat wrap for exhaust pipes, and reflective shields to protect nearby wiring and plastic components.

Exhaust System

The turbo itself acts as a restriction, but a free-flowing downpipe and exhaust are still critical. A high-flow catalytic converter (if staying emissions-compliant) or a straight-through exhaust reduces backpressure and helps the turbo spool more efficiently. Consider a 3-inch or larger system from the turbo back.

Engine Internals

This is the most debated area. The factory 6.4L HEMI uses a forged steel crank, but the pistons are hypereutectic aluminum and the rods are powdered metal. At boost levels above 8–10 psi (approximately 700–750 wheel horsepower), these components are at risk of failure. For builds targeting 800+ wheel horsepower, invest in forged pistons (e.g., from Diamond Racing or Manley), forged connecting rods (e.g., Manley H-beam or I-beam), and ARP head studs. This is expensive but prevents catastrophic engine failure.

Tuning and Calibration

No turbo kit performs right out of the box without proper tuning. The factory ECU (Powertrain Control Module) must be recalibrated to adjust fuel timing, air/fuel ratio, boost control, and safety parameters. Use a reputable tuning platform like HP Tuners and work with a tuner experienced in forced induction HEMIs. Options include remote tuning via datalogging or in-person dyno tuning. A poor tune can destroy an engine in minutes—do not skimp here.

Maintenance and Long-Term Reliability

A turbocharged vehicle requires more attentive maintenance than a naturally aspirated one. Follow these practices to keep your MRT kit and engine healthy:

  • Frequent Oil Changes: Turbos generate intense heat that can break down oil quickly. Use a high-quality synthetic oil and change it every 3,000 miles or after every track event.
  • Check for Boost Leaks: Inspect all intercooler couplers, vacuum lines, and wastegate connections regularly. A leak reduces performance and can cause lean conditions.
  • Let the Turbo Cool: After hard driving, idle the engine for 30–60 seconds before shutting off to allow oil to circulate and cool the turbo bearings. A turbo timer can automate this.
  • Monitor Air/Fuel Ratio: Install a wideband oxygen sensor and gauge to keep an eye on the air/fuel ratio during spirited driving. If it starts leaning out, back off immediately.
  • Inspect Heat Shields: Over time, heat wrap can degrade and shielding can shift. Re-wrap or replace as needed to protect components.

Conclusion

Selecting the right MRT Performance turbo kit for your 6.4L HEMI Challenger is a rewarding journey when approached methodically. Define your power goals, match the kit stage to your intended use, set a realistic total budget, and prepare for the necessary supporting modifications. Remember that a turbo system is part of a holistic engine package—fuel, cooling, exhaust, tuning, and possibly internals all must align.

Take the time to research, consult with experienced builders (both online communities and local shops), and never compromise on safety or quality. With the right MRT kit and proper execution, your Challenger will transform into a thrilling, high-powered machine that delivers the driving experience you dream of.