Understanding the Hennessey HPE600 Kit for the M133 Engine

The Mercedes-Benz M133 engine, found in the A45 AMG, CLA45 AMG, and GLA45 AMG, is a turbocharged four-cylinder known for its impressive factory output of 355–375 horsepower. The Hennessey HPE600 kit elevates this engine to approximately 600 horsepower and 500 lb-ft of torque by upgrading the air intake, intercooler, downpipe, exhaust system, and transmission programming. This comprehensive bolt-on package transforms the M133 into a serious performance contender while maintaining daily-driver civility.

This guide provides a detailed, step-by-step installation procedure for the HPE600 kit. Whether you are a seasoned technician or a student learning performance tuning, the following instructions are designed to be clear, complete, and safe. The entire job can be completed in a weekend with basic hand tools and a lift or jack stands.

Tools, Equipment, and Preparation

Required Tools and Supplies

  • Hennessey HPE600 kit (includes intake, intercooler, downpipe, exhaust, programming module)
  • Metric socket set (8mm–19mm) and wrenches
  • Torque wrench (capable of 20–120 N·m)
  • Breaker bar (for stubborn bolts)
  • Screwdriver set (flathead and Phillips)
  • Trim removal tools (for plastic fasteners)
  • Jack and four jack stands (or vehicle lift)
  • Safety glasses, mechanic’s gloves, and ear protection
  • Penetrating oil (e.g., WD-40 or PB Blaster)
  • Shop towels and brake cleaner
  • Service manual for your specific M133 vehicle model

Workspace and Vehicle Preparation

Park the vehicle on a level surface. Disconnect the negative battery terminal and isolate it to prevent accidental reconnection. Allow the engine to cool completely—contact with hot exhaust or turbo components can cause burns. Remove any loose objects from the engine bay. Review the entire Hennessey installation manual before beginning.

Safety Considerations

Working under a vehicle and handling sharp exhaust components carries inherent risks. Always use jack stands rated for the vehicle’s weight; never rely solely on a floor jack. Wear safety glasses when working under the car. The M133’s exhaust system can exceed 500 °F after operation—let the vehicle cool for at least one hour before working. Have a fire extinguisher nearby, and work in a well-ventilated area, especially when disconnecting fuel or coolant lines.

Step 1: Removing Stock Components

Air Intake Removal

Begin at the front of the engine bay. Loosen the clamps connecting the factory intake duct to the turbo inlet and the air filter housing. Remove the mass airflow sensor (MAF) connector and unclip the housing from its mounts. Lift out the entire intake tube and air box. Use a shop towel to cover the turbo inlet opening—this prevents debris from falling into the compressor.

Exhaust System Removal

Raise the vehicle securely on jack stands or a lift. Start at the downpipe, which connects the turbocharger to the mid-pipe. The M133 downpipe has two oxygen sensors—carefully unclip the wiring from their brackets before unbolting the pipe. Use a 13mm and 15mm socket to remove the downpipe flange bolts. Apply penetrating oil if bolts are seized. Support the exhaust system while removing hangers near the center resonator. Lower the entire rear section from the vehicle. Save all factory hardware; it may be reused for aftermarket components.

Intercooler Removal

The stock intercooler sits in the lower front bumper trim. Remove the undertray and front bumper cover as instructed in your service manual. Disconnect the intercooler charge pipes and unbolt the core from its mounts (usually three T30 Torx or 10mm bolts on each side). The M133 intercooler is small and heat-soaks quickly; the HPE600 replacement features a much larger bar-and-plate core for sustained power.

Step 2: Installing the Hennessey Air Intake

The HPE600 intake system replaces the restrictive factory airbox with a large cone filter and smooth aluminum tube. Position the new heat shield into the factory airbox location. Install the filter on the tube and secure it with the supplied clamp. Slide the intake tube over the turbo inlet and tighten the clamp to 4 N·m (35 in-lb). Reconnect the MAF sensor—make sure the wiring does not contact the belt or pulleys. Double-check that all rubber grommets seat properly to prevent unmetered air from entering the system.

Step 3: Installing the Hennessey Intercooler

Slide the larger HPE600 intercooler into the factory location. It may require slight trimming of the plastic bumper support tab for clearance—use a rotary tool or fine-tooth saw. Secure the intercooler with the provided brackets and hardware. Torque the bolts to 10 N·m (89 in-lb). Attach the silicone charge pipes to the intercooler outlets and tighten the T-bolt clamps. The on‑to‑one flow path eliminates several factory bends, reducing restriction.

Step 4: Installing the Hennessey Downpipe and Exhaust

Downpipe Installation

The HPE600 downpipe is a catted or catless high-flow unit (check local emissions regulations). Apply anti-seize compound to the turbo flange studs. Mount the downpipe gasket and slide the pipe into position. Tighten the flange nuts in a crisscross pattern to 25 N·m (18 ft-lb). Reattach the oxygen sensor wiring. The sensor threads should be coated with anti-seize (avoid the sensor tip).

Cat-Back Exhaust Installation

Assemble the mid-pipe and rear muffler section on the ground. Slide the assembly onto the downpipe outlet and loosely install the mounting brackets. Adjust the exhaust tip alignment so the tips are centered in the rear valance. Tighten all clamps and bracket bolts to specifications provided by Hennessey. Start the clamps at the front and work backward to prevent binding. Run the engine briefly to check for leaks and listen for rattles against the underbody.

Step 5: Installing the ECU and TCU Programming

The HPE600 kit includes a handheld tune module (or OBD flash device) that reprograms the engine control unit (ECU) and transmission control unit (TCU). This is the heart of the 600 HP gain. Connect the programmer to the OBD-II port under the dashboard. Follow the on‑screen prompts—the process takes about 15 minutes. Do not disconnect or start the engine during the flashing procedure. After completion, disconnect the tool and verify that no error lights remain on the dashboard.

Step 6: Reconnect the Battery and Perform System Checks

Reattach the negative battery terminal. Turn the ignition to “ON” (do not start) and let the fuel pump prime for five seconds. Check for any loose wires, hoses, or clamps. Verify that the intercooler and intake plumbing connections are secure. Inspect the exhaust system for any contact with subframe or body panels. Confirm that all oxygen sensors are plugged in and the wiring is heat‑wrapped near the turbo area.

Step 7: Start the Engine and Dial In

Start the engine with the air conditioning off. Let it idle for 30 seconds. The idle may be slightly rougher than stock due to the more aggressive tune, but it should steady. Rev the engine gently to 2500 rpm and listen for any air leaks (a hissing sound near intake joints). Check the downpipe connection for exhaust leaks. Allow the engine to reach operating temperature (coolant at 90 °C). The cooling fans should cycle on after a few minutes of idling.

Step 8: First Test Drive and Performance Evaluation

Drive the vehicle gently for the first five miles to let the ECU adapt and to heat‑cycle the exhaust components. Then perform a medium‑throttle pull from 30 to 60 mph. The HPE600 kit should deliver immediate, linear power with no flat spots. The turbo spools noticeably faster, and the exhaust note becomes deeper and more aggressive. Watch the dashboard for any warning lights related to the engine or transmission. If everything looks good, proceed to a full‑throttle pull in a safe, legal area. The transmission shifts more firmly, especially under load, thanks to the TCU recalibration.

Post-Installation Considerations and Maintenance

  • Break‑in period: Avoid sustained full‑throttle runs for the first 200 miles to allow the new exhaust gaskets and turbo seals to seat properly.
  • Oil changes: With 600 hp, the M133 oil temperature rises faster. Use a high‑quality full synthetic 5W‑40 meeting Mercedes‑Benz 229.51/229.52. Change oil every 5,000 miles or annually.
  • Spark plugs: The increased boost pressure may require shorter spark plug replacement intervals—every 20,000 miles is a safe guideline. Use iridium plugs gapped to 0.028 inches (0.7 mm).
  • Emissions compliance: If you live in an area requiring annual OBD testing, verify that your exhaust setup will not trigger a catalyst efficiency code. Some HPE600 downpipes include a high‑flow catalytic converter to avoid this.

Common Questions and Troubleshooting

Engine hesitation or stutter under boost

Check for a boost leak at the intercooler couplings or intake clamps. Retighten all silicone connectors. Also inspect the spark plugs—if the gap is too large, boost pressure can blow out the spark.

Check engine light on after installation

The most common cause is an unplugged or damaged oxygen sensor. Clear the code with a scan tool and verify connections. If the light returns, the downstream sensor may need a spacer to move it out of the main exhaust stream.

Transmission shifts harshly in automatic mode

The TCU tune increases clamp pressure. This is normal for the HPE600 profile. If the shifts become too aggressive for daily comfort, you can revert the TCU to stock using the handheld programmer while keeping the ECU tune.

Performance Expectations

Dyno results for the Hennessey HPE600 kit on an M133 engine typically show 590–620 wheel horsepower with 93 octane fuel. 0–60 mph times drop into the 3.2–3.4 second range for the A45 AMG. Quarter‑mile passes land in the 11.1–11.4 second bracket at 124–126 mph. On the street, the car feels significantly stronger above 3500 rpm, pulling hard to a 7200 rpm redline. The exhaust note is aggressive but without excessive drone on the highway thanks to the tuned muffler design.

Final Thoughts

Installing the Hennessey HPE600 kit on your M133‑powered Mercedes is one of the most rewarding upgrades you can perform. The package addresses the engine’s major restrictions—intake, intercooler, downpipe, exhaust, and tuning—delivering a cohesive increase of roughly 200 horsepower over the stock output. With careful installation and proper maintenance, the HPE600 provides reliable daily‑driver performance that can embarrass many exotics.

For additional technical details, refer to the official Hennessey HPE600 product page. The M133 engine’s architecture is discussed in depth on Wikipedia’s M133 article. For community support and installation tips, the MBWorld forum has several build threads. A useful torque specification guide for the M133 is available at MercedesMedic. Finally, a detailed installation video by Hennessey can be viewed on their YouTube channel.