Hennessey Venom 700 Upgrade for the C63 M177: Complete Installation Guide

Upgrading your Mercedes-AMG C63 with the Hennessey Venom 700 package transforms the M177 V8 into a true powerhouse. This comprehensive guide provides a step-by-step walkthrough for installing the Venom 700 upgrade, covering everything from initial preparation to final testing. Whether you are an experienced technician or a dedicated DIY enthusiast, this article ensures you perform the installation correctly and safely, unlocking the full potential of your C63.

The Venom 700 kit typically includes upgraded turbochargers, a high-flow intake manifold, revised intercooler piping, a performance ECU calibration, and upgraded exhaust components. This guide assumes you have basic mechanical knowledge and access to a fully equipped garage. For any steps beyond your comfort level, consult a professional Hennessey-authorized installer.

Tools and Materials You Will Need

Before beginning, gather all required equipment. Using the correct tools prevents damage and ensures proper torque specifications are met. Below is a comprehensive list organized by category.

Hand Tools and Specialty Items

  • Socket and ratchet set (metric, ¼-inch and ⅜-inch drive, with extensions and universal joints)
  • Torque wrench (capable of 5–150 Nm, calibrated)
  • Combination wrenches (8–19 mm, open-end and box-end)
  • Screwdriver set (flat-head, Phillips, and Torx bits T25–T50)
  • Pliers (standard, needle-nose, and snap-ring pliers)
  • Trim removal tools (plastic pry bars for interior panels and clips)
  • Turbocharger alignment tool (if included in the kit, or use a soft brass drift)
  • Coolant and oil recovery containers

Consumables and Fluids

  • Engine oil (Mercedes-Benz 229.5 or 229.52 approved, 0W-40 or 5W-40, approximately 8 liters)
  • Coolant (MB 326.0 approved ethylene glycol concentrate, premixed 50/50)
  • Threadlocker (medium-strength blue Loctite 243 for critical fasteners)
  • Anti-seize compound (for exhaust bolts and turbo mounting studs)
  • Shop towels and brake cleaner
  • Zip ties and electrical tape (for re-routing harnesses)

Safety Gear

  • Safety goggles
  • Mechanics gloves (cut-resistant)
  • Jack stands (minimum 3-ton capacity, two pairs)
  • Floor jack
  • Fire extinguisher (rated for Class B and C fires)

Preparation and Workspace Setup

Proper preparation reduces the risk of mistakes and ensures a smooth installation. Park the vehicle on a level concrete surface and disconnect the negative battery terminal. Allow the engine to cool completely — the M177 runs hot, and working on a warm engine increases the risk of burns and warped gaskets.

Remove the engine cover by unscrewing the four Torx T30 bolts and lifting it straight up. Set it aside in a safe location. Next, drain the engine oil and coolant to prevent spills during component removal. Open the oil drain plug and coolant drain valve (located at the bottom of the radiator on the driver’s side). Capture all fluids in proper containers for disposal. Reinstall the drain plugs with new washers after draining.

Clean the engine bay thoroughly using a degreaser and low-pressure water. Remove any debris, dirt, or grease from the intake and exhaust system areas. This prevents contamination when you open the systems. Cover the alternator and any exposed electrical connectors with plastic bags to protect them from moisture.

Removing the Stock Components

Removing the factory parts requires patience and attention to detail. Work systematically, labeling each fastener and connector as you go. Take photos before disconnecting anything — this will save hours during reassembly.

Step 1: Remove the Intake System

Disconnect the mass air flow (MAF) sensor connector and unclip the intake duct from the air box. Remove the air box assembly by unscrewing the two 10 mm bolts at the base. Set the air box and filter aside. Loosen the clamps on the intercooler pipes and pull them free from the throttle body. Cap the throttle body opening with a clean rag to prevent debris entry.

Step 2: Detach the Exhaust System

Raise the vehicle on jack stands and support the exhaust system with a jack or strap. Unbolt the downpipes from the turbocharger outlets — these fasteners are often rusted, so apply penetrating oil and allow it to soak for 15 minutes. Remove the mid-pipe and muffler section if required by the Venom 700 kit (some kits reuse the factory rear section). Hold the exhaust hangers with pliers and slide the rubber isolators free. Lower the exhaust system and move it out of the way.

Step 3: Remove the Turbochargers

Disconnect the oil feed and return lines from each turbocharger. Plug the openings with clean caps or tape to keep debris out. Unbolt the turbocharger mounting brackets from the cylinder head — there are four 13 mm bolts per turbo. Carefully lift each turbocharger free from the exhaust manifold studs. Inspect the studs for damage and replace any that are bent or corroded. Repeat for the secondary turbo on the passenger side.

Step 4: Remove the Intercooler and Pipes

Unbolt the intercooler from its mounting bracket (two 10 mm bolts). Slide the intercooler downward and out through the lower grille opening. Remove all factory intercooler piping, including the hard pipes and silicone couplers. Set them aside — you will not reuse them.

Installing the Hennessey Venom 700 Upgrade

With the stock components removed, you can now install the Venom 700 hardware. Follow the instructions included with your specific kit, but the general procedure below covers the most common steps.

Step 1: Install the Upgraded Turbochargers

Apply a thin coat of anti-seize to the exhaust manifold studs. Position the new turbochargers onto the studs, ensuring the oil drain ports face downward. Hand-tighten the mounting nuts, then torque them to 35 Nm in a cross pattern using a torque wrench. Connect the oil feed lines using new copper washers and tighten to 25 Nm. Attach the oil return lines with new gaskets and tighten to 20 Nm. Reinstall the turbocharger heat shields using the original bolts.

Step 2: Install the Upgraded Intake Manifold

Clean the intake port surfaces on the cylinder head with brake cleaner. Place the new Hennessey intake manifold gasket onto the head. Position the intake manifold and hand-tighten the 12 mm bolts. Torque them to 22 Nm in the sequence specified in the kit instructions (usually from the center outward). Reconnect all vacuum lines and sensors to the intake manifold. The Venom 700 kit typically includes a new map sensor — install it and connect the harness.

Step 3: Install the Intercooler and Piping

Mount the upgraded intercooler into the factory location using the provided brackets. Tighten the bolts to 10 Nm. Connect the new intercooler piping and silicone couplers. Use the supplied T-bolt clamps and tighten them evenly to 6 Nm. Ensure all connections are secure and the pipes do not rub against the chassis or engine components. Route the blow-off valve (BOV) recirculation hoses as directed — incorrect routing can cause boost leaks.

Step 4: Install the Performance Exhaust System

If your Venom 700 kit includes a cat-back exhaust, start by hanging the rear section from the factory isolators. Work forward, connecting the mid-pipe and downpipes. Use new gaskets at each joint and tighten the bolts to 40 Nm. Ensure the exhaust tips are aligned evenly with the rear bumper cutouts. If reusing the factory rear section, simply connect the downpipes to the existing system using the provided adapters.

Step 5: ECU Calibration

The Venom 700 upgrade requires a specific ECU tune to optimize fuel delivery, ignition timing, and boost pressure. The kit includes a handheld programmer from Hennessey. Connect it to the OBD-II port and follow the on-screen instructions to flash the new calibration. Do not interrupt the flashing process — it takes approximately 10–15 minutes. Once complete, start the engine and verify it idles smoothly. If the engine misfires or runs roughly, stop immediately and recheck all connections.

Reconnecting Systems and Refilling Fluids

With all hardware installed and the ECU calibrated, it is time to reconnect the vehicle systems and fill fluids.

Battery and Electrical Connections

Reconnect the negative battery terminal and tighten it to 10 Nm. Reconnect any electrical connectors you detached during disassembly, including MAF sensor, map sensor, turbo actuators, and BOV solenoid. Use zip ties to secure any loose harnesses away from heat sources.

Coolant and Oil Refill

Fill the cooling system with the approved coolant mixture. Use a vacuum filler tool if available to prevent air pockets. Start the engine and allow it to reach operating temperature with the heater set to maximum. Top off the coolant reservoir as needed. Refill the engine with 7.5 liters of fresh oil. Check the oil level using the dipstick — the M177 holds roughly 8 liters with filter. Add oil in 0.5-liter increments until the level reaches the full mark.

Bleeding the Cooling System

Run the engine at 2,000 rpm for 2–3 minutes to circulate coolant. Watch for air bubbles in the expansion tank. If bubbles appear, cap the tank and let the engine cool, then repeat the process. Ensure the coolant level stabilizes between the MIN and MAX lines.

Final Checks and System Testing

Perform a thorough inspection before taking the vehicle on the road.

Leak Inspection

Visually inspect all connections for coolant, oil, or boost leaks. Pay special attention to turbocharger oil lines, intercooler couplers, and exhaust gaskets. Use a soapy water spray bottle to check for boost leaks — spray the connections while the engine idles. Bubbles indicate leaks that must be addressed immediately.

Torque Verification

Re-torque all critical fasteners after the initial heat cycle. This includes turbocharger nuts, intake manifold bolts, and exhaust downpipe fasteners. The heat expansion can loosen fasteners during the first warm-up.

Electrical System Check

Turn on the headlights, air conditioning, and other accessories to verify alternator output and battery voltage. Check that all dashboard warning lights extinguish after engine start. If the check engine light remains illuminated, use the programmer to read diagnostic codes. Common post-installation codes include P0234 (overboost) or P0101 (MAF circuit) — these usually indicate a loose connection or incorrect calibration.

Test Drive and Performance Evaluation

The test drive is the most critical phase of the installation. Proceed carefully and monitor the vehicle closely.

Initial Low-Load Drive

Drive for 10–15 minutes at low throttle and moderate RPMs (2,000–4,000). This allows the upgraded components to bed in and the ECU to adapt. Listen for unusual whistles, rattles, or vibrations. Note any hesitation during tip-in throttle response.

Full Boost Testing

Find a safe, empty road. Gradually apply full throttle from 3,000 rpm in third gear. The Venom 700 kit should deliver a strong surge of power up to the 7,000 rpm redline. Watch the boost gauge — peak boost should be around 18–20 psi (1.24–1.38 bar). If boost exceeds 22 psi, lift off immediately and recheck the wastegate actuator settings. Perform two to three full-throttle runs, then allow the engine to cool by cruising at highway speeds for 5 minutes.

Temperature Monitoring

After a hard run, bring the vehicle to a stop and monitor the coolant temperature gauge. It should stabilize at around 90–100°C (194–212°F). The oil temperature should remain below 120°C (248°F) under spirited driving. If temperatures climb rapidly, check for coolant flow issues or oil cooler blockage.

Post-Installation Maintenance

Maintaining your upgraded C63 is essential for longevity and consistent performance.

Oil Change Intervals

Shorten your oil change interval to 5,000 miles (8,000 km) or every six months. The increased heat and boost put more stress on the oil. Use only the approved viscosity and MB specification. Consider using a high-ZDDP oil for older M177 engines, as the Venom 700 upgrade increases camshaft and valvetrain loads.

Spark Plug Replacement

Replace spark plugs every 10,000 miles (16,000 km) with the colder heat range specified in the Venom 700 kit. Gap them to 0.024 inches (0.6 mm) for boosted applications. Incorrect gap can cause misfires under full load.

Fuel Quality

Always run 93 octane (98 RON) fuel or higher. The Venom 700 calibration is designed for premium fuel. Using lower octane can cause detonation and engine damage. If you live in an area with limited access to high-octane fuel, consider a flex-fuel tune from Hennessey.

Troubleshooting Common Issues

Even with careful installation, issues can arise. Below are the most common problems and their solutions.

Boost Leaks

Symptoms include hesitation under full throttle, high boost readings, and a hissing sound. Inspect all intercooler hose clamps and tighten them to 6 Nm. Check the BOV diaphragm for tears. A boost leak test with a pressure tester can pinpoint small leaks.

Check Engine Light for Cylinder Misfires

Misfire codes (P0300–P0308) often stem from spark plug gap or fuel quality. Verify the plugs are gapped correctly and the fuel octane meets the requirement. If the issue persists, inspect the coil packs for cracks or arcing. The Venom 700 kit can push the factory coils to their limit — upgrade to higher-performance coils if needed.

Overheating

If the coolant temperature exceeds 110°C (230°F) during normal driving, check for airflow obstruction at the intercooler and radiator. The larger intercooler can restrict airflow to the radiator if not properly shrouded. Consider upgrading to a high-flow fan shroud if temperatures remain high.

Turbocharger Whistle or Surge

A high-pitched whistle during boost may indicate a small boost leak or a damaged turbo compressor wheel. Remove the intake duct and inspect the wheel for contact marks. Surge (a fluttering sound) occurs when the BOV is stuck closed or the recirculation hose is blocked. Clean or replace the BOV as needed.

Professional Resources and Support

If you encounter issues beyond your expertise, do not hesitate to seek professional help. Hennessey Performance offers a network of authorized installers who can complete the upgrade and fine-tune the calibration. Additionally, the Mercedes-AMG community provides extensive knowledge through forums and dedicated Facebook groups. Below are some external resources to assist you further.

Conclusion

The Hennessey Venom 700 upgrade is one of the most rewarding modifications you can make to the C63 M177. This guide walks you through each phase, from preparation to final testing. The upgrade transforms daily driving and track performance, delivering a visceral power increase that matches the car’s aggressive styling. By following these steps and respecting the mechanical limits of the stock engine, you can enjoy a reliable 700-horsepower experience for years. If anything remains unclear, refer back to the specific sections above or consult a certified Hennessey installer. The Venom 700 is a significant investment in performance — treat the installation with the same care and precision that Hennessey puts into their engineering.