Mercedes-Benz AMG V8 engines represent some of the finest performance engineering in the automotive world. Whether you own a naturally aspirated M156/M159 or a twin-turbo M157/M177/M178, your AMG is already fast—but it can be so much faster.
After tuning dozens of AMG vehicles here at Raw Exotics, I can tell you that these German V8s respond incredibly well to modification. The factory leaves significant power on the table for reliability and emissions reasons, and unlocking that potential is easier than you might think. This guide covers everything you need to know about getting started with AMG tuning.
Understanding AMG V8 Engine Platforms
Mercedes has produced several distinct AMG V8 platforms over the past two decades. Each has unique characteristics and modification potential.
M113K - Supercharged 5.4L/5.5L (2002-2006)
The M113K is the supercharged predecessor to the modern AMG engines. Found in the C55, CLK55, E55, CLS55, S55, SL55, and G55.
Key specs:
- Displacement: 5,439cc (5.4L) or 5,546cc (5.5L)
- Power: 469-510 hp (varies by model)
- Torque: 516-553 lb-ft
- Forced induction: Roots-type supercharger (Lysholm screw in later models)
- Compression: 9.0:1
Tuning potential: The M113K responds amazingly well to tuning. A simple ECU flash can add 50-80 hp. With pulley upgrades and supporting mods, 600-650 hp is achievable on pump gas.
M156 - Naturally Aspirated 6.2L (2007-2014)
The M156 is the legendary naturally aspirated 6.2L V8 found in the C63, E63, CLS63, ML63, S63, and SL63 AMG models from 2007-2014. This is the engine that made AMG famous for its incredible sound and high-revving nature.
Key specs:
- Displacement: 6,208cc (6.2L)
- Power: 451-507 hp (varies by model year and variant)
- Torque: 443-465 lb-ft
- Aspiration: Naturally aspirated
- Compression: 11.3:1
- Redline: 7,200 RPM
Tuning potential: The M156 is somewhat limited as an NA engine, but proper tuning combined with bolt-ons can yield 480-530 hp. For serious power, forced induction is the way to go (more on that later).
M157 - Twin Turbo 5.5L (2012-2017)
The M157 replaced the M156 with a smaller-displacement but twin-turbocharged design. Found in C63, E63, S63, CLS63, and G63 AMG models.
Key specs:
- Displacement: 5,461cc (5.5L)
- Power: 518-585 hp (varies by tune level)
- Torque: 516-664 lb-ft
- Forced induction: Twin turbochargers
- Compression: 10.0:1
Tuning potential: The M157 is a tuner's dream. ECU tuning alone can add 80-120 hp. With downpipes and a quality tune, 700+ hp is easily achievable. Built motors are pushing 1,000+ hp.
M177/M178 - Twin Turbo 4.0L (2015-Present)
The current generation AMG V8 uses a "hot-V" configuration with the turbos mounted inside the V of the engine for reduced lag and packaging.
Key specs:
- Displacement: 3,982cc (4.0L)
- Power: 469-630 hp (varies by model and tune)
- Torque: 465-664 lb-ft
- Forced induction: Twin turbochargers (hot-V config)
- Compression: 8.6-10.5:1 (varies by variant)
Tuning potential: Excellent response to tuning. Stage 1 tunes add 80-100 hp. Full bolt-on cars are making 700-750 hp. AMG GT Black Series variants are making 720 hp stock and can exceed 900 hp with mods.
ECU Tuning: The Foundation of Power
For any AMG platform, ECU tuning is the single most important modification. The factory ECU programming is conservative—designed for reliability, emissions, fuel economy, and component longevity. Performance is secondary.
How AMG ECU Tuning Works
AMG ECU tuning involves rewriting the engine management software to optimize performance parameters:
- Ignition timing: More aggressive timing advance for more power
- Fuel maps: Richer air-fuel ratios for maximum power (while staying safe)
- Boost control (turbo models): Higher boost pressure for significantly more power
- Throttle mapping: Sharper throttle response
- Rev limiter: Raised redline (when safe)
- Speed limiter: Removed or raised electronic top speed limit
- TCU tuning: Faster shifts, more aggressive shift points, launch control
Popular AMG Tuning Platforms
Weistec Engineering: One of the most respected AMG tuners in the world. Offers everything from ECU flashes to complete supercharger and turbo kits. Known for reliable, well-engineered solutions.
- ECU tuning: $1,200-2,000
- TCU tuning: $800-1,200
- Combined ECU + TCU packages: $1,800-3,000
Eurocharged: Specializes in AMG ECU tuning with excellent customer support and proven results. Offers various stage tunes for different platforms.
- Stage 1 (ECU only): $1,200-1,500
- Stage 2 (ECU + bolt-ons): $1,500-2,000
- TCU tuning: $800-1,000
VR Tuned: Remote tuning specialist with a large AMG customer base. Good value option with solid results.
- Flash tuning: $800-1,400
- Custom tuning: $1,200-1,800
Raw Exotics (us!): We use a combination of Weistec, Eurocharged, and custom in-house calibrations depending on the specific platform and customer goals.
Expected Power Gains from ECU Tuning
Here's what you can realistically expect from a quality ECU tune on different AMG platforms:
- M113K (supercharged): 50-80 hp gain with ECU tune alone
- M156 (NA 6.2L): 20-35 hp gain with ECU tune alone
- M157 (twin turbo 5.5L): 80-120 hp gain with ECU tune alone
- M177/M178 (twin turbo 4.0L): 80-100 hp gain with ECU tune alone
These are conservative, proven numbers. Some cars may see slightly higher gains depending on condition and baseline power.
Bolt-On Modifications
After ECU tuning, these bolt-on mods provide the best bang-for-buck power gains:
Exhaust System Upgrades
Downpipes (turbo models only): Replacing the restrictive factory catalytic converters with high-flow downpipes is the single best bolt-on mod for turbo AMGs.
- Power gain: 30-60 hp (combined with tune)
- Improved turbo spool and boost response
- Much more aggressive exhaust note
- Cost: $1,200-2,500 for quality downpipes
Cat-back exhaust: Less power gain than downpipes, but still worthwhile for sound and minor power improvements.
- Power gain: 10-20 hp
- Weight reduction (many aftermarket exhausts are lighter)
- Enhanced exhaust note
- Cost: $2,000-5,000 depending on brand (Akrapovic, Armytrix, Capristo, etc.)
Intake Systems
A quality aftermarket intake provides modest power gains and improved induction sound.
- Power gain: 8-18 hp
- Better throttle response
- Aggressive induction noise
- Cost: $600-1,200
Popular brands: Eventuri (premium option), APR, Gruppe M, BMC.
Intercooler Upgrades (Turbo Models)
The factory intercoolers on M157/M177/M178 engines are adequate for stock power but become a bottleneck with tuning. Upgraded intercoolers maintain lower charge air temperatures, preventing heat soak and power loss.
- Power gain: 0-20 hp (primary benefit is consistency and heat soak prevention)
- Critical for track use or aggressive street driving
- Cost: $1,500-3,500 depending on design
Forced Induction for M156 (6.2L NA Engines)
The M156 is a brilliant naturally aspirated engine, but if you want serious power, forced induction is the answer.
Weistec Supercharger Kit
Weistec offers a comprehensive supercharger kit for M156 engines that transforms the car.
- Power output: 650-750 hp depending on pulley and boost level
- Instant throttle response (maintains NA character with added punch)
- Complete kit with intercooling, fuel system, and tuning
- Cost: $15,000-20,000 installed
Turbocharger Kits
Several companies offer turbo kits for M156, though these are less common than superchargers.
- Power output: 700-900+ hp with built motor
- More complex installation
- Some turbo lag compared to supercharger
- Cost: $12,000-18,000 for kit + installation
Real-World AMG Build Examples
Here are some actual AMG builds we've completed at Raw Exotics:
Build 1: 2015 C63 AMG S (M157)
- Eurocharged Stage 2 ECU + TCU tune: $2,200
- Weistec downpipes: $2,000
- Eventuri carbon intake: $1,200
- Installation and dyno tuning: $1,200
- Total cost: $6,600
- Result: 557 hp (stock) → 685 hp (110+ hp gain)
Build 2: 2012 E63 AMG (M156)
- Weistec supercharger kit: $17,500
- Headers and exhaust: $3,500
- Upgraded fuel system: $2,000
- Installation and tuning: $3,000
- Total cost: $26,000
- Result: 451 hp (stock) → 715 hp (264 hp gain)
Build 3: 2018 AMG GT S (M178)
- VR Tuned Stage 1: $1,400
- IPE cat-back exhaust: $4,200
- BMC air filters: $300
- Total cost: $5,900
- Result: 515 hp (stock) → 590 hp (75 hp gain)
Common AMG Issues to Address
Before modifying your AMG, address these common platform issues:
M156 Head Bolt Failure
Early M156 engines (2007-2011) have a known issue with head bolts failing, leading to coolant leaks or catastrophic engine damage.
Solution: Replace head bolts with updated design. Cost: $3,000-5,000 for professional replacement. Critical for peace of mind on early M156 engines.
M157 Turbocharger Failure
Some M157 engines experience turbo failures, often due to oil starvation or contamination.
Prevention: Use quality oil, change regularly (5,000 miles or less), and address any oil leaks immediately.
Transmission (722.9 Seven-Speed Auto)
The 722.9 transmission in many AMG models is a known weak point, especially with added power.
Solutions:
- TCU tuning to optimize shift points and reduce wear
- Transmission cooler for track use
- Regular fluid changes (every 30,000 miles)
- For high-power builds (700+ hp), consider upgraded clutch packs or valve body
Recommended Modification Path
Here's the order I recommend for building an AMG:
Stage 1 (ECU Tune Only)
- ECU flash tune
- TCU tune (if applicable)
- Cost: $1,500-2,500
- Power gain: 50-120 hp depending on platform
Stage 2 (ECU + Bolt-Ons)
- ECU + TCU tuning
- Downpipes (turbo models)
- Intake system
- Cost: $4,000-7,000
- Power gain: 80-150 hp depending on platform
Stage 3 (Full Bolt-Ons)
- Everything from Stage 2
- Cat-back exhaust
- Upgraded intercoolers (turbo models)
- Headers (NA models)
- Cost: $8,000-14,000
- Power gain: 100-180+ hp depending on platform
Stage 4 (Forced Induction for M156, or Built Internals for Turbo Models)
- Supercharger/turbo kit (M156)
- Forged internals (turbo models going 800+ hp)
- Upgraded fuel system
- Transmission upgrades
- Cost: $15,000-35,000+
- Power potential: 700-1,000+ hp
"AMG V8s are some of the most rewarding engines to tune. The turbo models respond incredibly to ECU tuning and bolt-ons, while the M156 NA motors have that intoxicating sound that gets even better with exhaust mods. These are hand-built engines from the factory—they deserve proper performance tuning."
Ready to Tune Your AMG?
If you're in Houston and ready to unlock your AMG's potential, Raw Exotics can help. We specialize in European performance tuning and have extensive experience with all AMG platforms—from M113K supercharged beasts to the latest M177/M178 twin turbos.
We'll help you choose the right modifications for your goals and budget, handle professional installation, and provide custom tuning that maximizes power while maintaining reliability. Call us at (713) 299-1168 or visit our shop to discuss your AMG build.