Why Turbocharge Your 5.7L HEMI Challenger?

Adding forced induction to a naturally aspirated 5.7L HEMI transforms the driving character of your Dodge Challenger. A properly designed turbo kit can push output well beyond 500 rear-wheel horsepower while maintaining daily-driver civility. Unlike a centrifugal supercharger setup, turbochargers spool from exhaust pressure, offering a linear powerbuild that rewards higher RPM. The installation is a substantial project, but one that pays dividends in acceleration and top-end pull.

Before starting, decide on a kit that matches your performance goals and budget. Kits from Hellion, STS, or Trick Performance typically include all necessary components: turbo manifolds, turbocharger, wastegate, blow-off valve, intercooler, oil feed/return lines, intake piping, and a boost controller. Some kits also include a tune file for the ECU. This guide assumes you have a complete turbo kit and basic mechanical experience. If you're new to forced induction, consider enlisting a shop with HEMI turbo experience.

Tools and Materials Needed

Gather the following before starting. Having everything on hand avoids frustrating mid-project trips to the store.

  • Socket and wrench set (metric and SAE, 1/4" and 3/8" drive)
  • Torque wrench (ft-lb for fasteners, in-lb for delicate sensors)
  • Screwdrivers (flathead and Phillips of various sizes)
  • Picks, pliers (needle-nose, slip-joint, hose clamp pliers)
  • Pipe wrenches for rusted connections
  • Vacuum pump for cooling system refill
  • Coolant (Mopar OAT or compatible type)
  • Engine oil (5W-20 or 5W-30 as per tuner recommendation)
  • Gaskets: exhaust manifold gaskets, turbo flange gasket, throttle body gasket
  • Wire connectors, heat shrink, electrical tape
  • Safety glasses, nitrile gloves, shop towels
  • Jack and jack stands (or drive-on ramps)
  • Shop vacuum for cleaning

Preparation Steps

Secure the Vehicle and Disconnect Power

Park on level ground, chock the rear wheels, and disconnect the negative battery terminal. The battery is located in the trunk on Challengers; disconnect it there. The ECU may store learned values; disconnecting power resets them so the new tune can adapt cleanly.

Drain Coolant

Place a drain pan under the radiator petcock (driver side lower corner). Open the petcock and remove the radiator cap to allow flow. Drain into an appropriate container for recycling. Also remove the lower radiator hose to fully empty the block. This gives access to the front of the engine and turbo placement.

Remove Engine Cover and Intake Components

Lift off the plastic engine cover (it’s held by push tabs). Remove the air intake tube from the throttle body to the airbox. Unclip the mass airflow sensor and set it aside. Remove the entire airbox assembly. This opens up the front and driver side of the engine bay.

Label Wiring and Hoses

Use painter’s tape and a marker to label every connector and hose you disconnect. Pay special attention to the throttle body electrical connector, MAP sensor, PCV hose, and brake booster vacuum line. A wrong connection during reassembly can cause drivability issues or set a check engine light.

Removing Stock Components

Remove the Factory Air Intake System

Loosen the clamp at the throttle body and pull the intake tube. Unbolt the airbox from the inner fender using a 10mm socket. Remove the silicone elbow from the throttle body. Set aside all parts; they can be reused if you ever revert to stock.

Disconnect and Remove the Throttle Body

Unplug the electrical connector (press the tab and wiggle). Loosen the four T30 Torx bolts holding the throttle body to the intake manifold. Gently pull the throttle body away. Place it in a clean bag to avoid contamination. Cover the intake opening with a clean rag to prevent debris from falling in.

Remove the Stock Exhaust Manifolds

The 5.7L HEMI has two exhaust manifolds, one per bank. The driver side is more accessible; the passenger side requires working around the alternator and A/C compressor. Use penetrating oil on the manifold bolts if they are rusted. Loosen bolts gradually from the outer edges inward to prevent warping. Lift the manifold off; you may need to wiggle it past the studs. On some models, you'll need to disconnect the steering shaft at the intermediate joint on the driver side to get enough clearance.

Remove Necessary Sensors and Wiring Harnesses

Disconnect the oxygen sensors (both upstream and downstream) using an O2 sensor socket or 22mm wrench. Unclip the harness from the valve covers and set it aside. If your kit relocates the O2 sensors, you’ll need to extend the wiring. Plan where the new sensor bungs will be on the turbo downpipe.

Installing the Turbo Kit

This is the core of the installation. Follow the kit's instructions, but here's a general outline.

Install the New Turbo Manifold

Place the new exhaust manifold (turbo flange) against the cylinder head. Use new gaskets (OEM or high-temp copper). Hand-start all bolts, then tighten to the manufacturer’s torque spec (usually 18-20 ft-lb for M8 bolts). Work from the center outward. On the driver side, ensure the wastegate actuator bracket clears the frame rail.

Attach the Turbocharger

Mount the turbo to the manifold using the supplied gasket and hardware. Tighten the V-band clamp or bolts securely. Prime the turbo before first startup by spinning it with a small amount of oil through the feed port. This prevents dry bearing wear during the first seconds of engine running.

Connect Oil Feed and Return Lines

The oil feed line runs from a port on the oil filter housing or a sandwich plate to the turbo center section. The return line (drain) goes from the bottom of the turbo back to the oil pan. Usually, you’ll tap the oil pan for a -10AN fitting. Remove the pan, drill, and weld (or use a thread-in bung). Clean all metal shavings. Use Teflon paste on threaded fittings, not tape, to prevent pieces from entering the oil system. Ensure the drain line has a constant downward slope with no dips that could trap oil and cause seal failure.

Install the Intake Piping and Filter

Run the intake tube from the turbo compressor outlet to the throttle body. Most kits include a silicone hose with a blow-off valve flange. Mount the intake filter (large cone filter) in a clean, cool air location—usually behind the front bumper or inner fender. Use a heat shield if possible to keep intake air temperatures down.

Reconnect the Throttle Body

Bolt the throttle body onto the new intake manifold (if it’s part of the kit) or onto the factory manifold if it’s retained. Use a new gasket. Torque to 89 in-lb (10 N·m). Reattach the electrical connector. The throttle body position may need recalibration in the tune; most tuners handle this.

Connecting the Intercooler

The air-to-air intercooler reduces intake air temperature, increasing density and power. It also prevents detonation.

Mount the Intercooler

Position the intercooler in front of the radiator, behind the bumper cover. Use the supplied brackets to secure it to the crash bar or frame rails. Ensure it is level and straight. Trim the plastic bumper support if necessary. The bottom of the intercooler should be at least 2" off the ground to avoid scraping on parking curbs.

Connect Piping

Route the charge pipe from the turbo compressor outlet to the intercooler’s inlet (one side of the core). Another charge pipe runs from the intercooler outlet to the throttle body. Use T-bolt clamps on all silicone couplers. Tighten evenly to prevent leaks. Apply a small amount of silicone lubricant to the pipe ends for easier assembly.

Ensure Leak-Free Connections

After all clamps are tightened, perform a boost leak test. Block the throttle body side with a rubber plug or block-off plate. Use a compressed air fitting with a regulator to pressurize the system to 15-20 psi. Listen for hissing. Common leak points: coupler joints, blow-off valve gasket, wastegate actuator arm. Repair any leaks before proceeding.

Wiring and Electronics

Connect Boost Controller

Most turbo kits include a manual or electronic boost controller. For a simple manual controller (ball-spring type), tee into the line from the turbo compressor housing to the wastegate actuator. For an electronic one (like a BoostController or solenoid), follow the specific wiring diagram. The solenoid typically gets power from a switched 12V source (e.g., windshield wiper motor fuse) and ground. Route the control wires away from spark plug wires and ignition coils to avoid EMI.

Install Additional Sensors

Many aftermarket ECUs or piggyback systems require a MAP sensor (manifold absolute pressure) and an intake air temperature sensor. Weld a bung into the charge pipe near the throttle body. Connect the sensor wiring to the ECU (0-5V signal, 5V reference, ground). Also consider a wideband O2 sensor for tuning feedback; weld a bung into the downpipe at least 18" from the turbine outlet.

Verify All Electrical Connections

Double-check that you haven't left any connectors unplugged. Verify the fuel pump wiring—if you upgraded to a higher-flow pump, ensure it is properly fused and relayed. Check the battery positive terminal for clearance from any turbo heat shield or piping.

Final Assembly Steps

Reinstall Engine Cover and Components

If your kit allows, replace the engine cover (some turbo systems require removing it permanently). Reattach any wiring harnesses you unclipped. Install the front bumper cover if removed. Ensure all fasteners are tight—loose bolts can lead to rattles or contact with rotating parts.

Refill Coolant and Oil

Use the vacuum pump to refill the cooling system to prevent air pockets. If unavailable, pour slowly and burp the system by squeezing the upper radiator hose while running. Fill oil through the valve cover filler cap; use the weight recommended by your tuner. Crank the engine with the starter (fuel pump relay disconnected) until oil pressure registers on the gauge—this pre-oils the turbo bearings.

Reconnect Battery

Reconnect the negative terminal. Turn the key to ON (not START) and allow the fuel pump to prime. Check for fuel leaks around the injectors (if you changed them). Check for oil leaks at the turbo feed and drain connections. If everything looks dry, proceed to startup.

Testing the Installation

Start and Idle Check

Start the engine. It may idle rough initially if the tune hasn't been loaded. Let it idle for 2-3 minutes, then shut off and check fluids again. Look under the car for any drips. Listen for unusual noises from the turbo area—a scraping sound indicates the compressor wheel is contacting the housing, requiring immediate shutdown.

Leak Check Under Load

With the engine warm, gently rev to 2500 RPM and hold for a few seconds. Inspect all charge pipes and intercooler connections for air leaks. Use a soapy water spray; bubbles indicate a leak. Tighten or reposition clamps as needed.

Boost Level Verification

If using a boost gauge, briefly apply part throttle (no more than 50%) while driving in 3rd gear. Boost should climb smoothly. Stay within the kit’s safe range (typically 6-8 psi on a stock bottom end). Do not go full throttle until the tune is final. Log boost, fuel pressure, and wideband AFR to send to your tuner.

Test Drive and Care

Take a short drive, keeping RPM under 4000 and boost below 5 psi for the first 50 miles to seat rings. Gradually increase load. Monitor gauges constantly. After 500 miles, change the oil and inspect the turbo for any oil leaks. The first oil change is critical because the turbo may shed tiny metallic particles during break-in.

Tuning: The Final Piece

A turbocharger without proper tuning is a recipe for detonation and engine failure. You need a custom calibration from a reputable HEMI tuner. Options include HP Tuners, DiabloSport, or a mail-order tune from companies like MMX or HHP. The tune adjusts fuel tables, ignition timing, throttle mapping, and transmission shift points (for automatics). Provide your tuner with data logs at various boost levels. Never attempt to run the car on the stock tune—fueling and timing are way too aggressive for boost.

Maintenance and Upkeep

Turbocharged cars require more frequent oil changes (every 3,000-4,000 miles). Use high-quality synthetic oil (5W-30 recommended). Check the intercooler piping for loose clamps annually. Inspect the turbo for shaft play when changing oil. Keep an eye on the wastegate actuator for signs of heat stress—it can crack if the turbo is heat-soaked after a long pull.

Conclusion

Installing a turbo kit on your 5.7L HEMI Challenger is one of the most rewarding upgrades you can perform. The process requires patience, attention to detail, and a willingness to learn. When done correctly, you’ll have a car that outruns many V8s costing twice as much. Whether you choose a budget DIY kit or a premium turnkey system, the thrill of spooling a turbo in a Dodge Challenger never gets old. For further reading, check out Hemi Tuner’s turbo comparison guide or Forced Inductions’ kit reviews. Always verify compatibility with your specific model year—small differences in engine bay layout can trip up even experienced installers.