ECU Tuning, M177, Mercedes-AMG - September 27, 2026

M177 vs M178 — AMG's Two 4.0T V8s Explained

The M177 and M178 are two versions of AMG's 4.0-liter twin-turbo V8, and the confusion between them is widespread. They share a displacement, a bore and stroke, and a hot-V turbo layout — but they are not the same engine. Here's what actually separates them, which AMGs use which, and how the differences affect tuning.

The Basics: What They Share

Both engines are built on the same fundamental architecture:

Displacement: 3,982 cc (4.0L)
Configuration: 90-degree V8
Bore x Stroke: 83 mm x 92 mm
Compression Ratio: 10.5:1
Turbocharging: Twin BorgWarner turbochargers in a hot-inside-V layout (turbos mounted between the cylinder banks)
Fuel Injection: Bosch piezo-electric direct injection with multi-pulse capability
Block Material: Aluminum alloy with Nanoslide cylinder liners (plasma-sprayed iron-carbon coating)
Head Material: Aluminum alloy

The engines share many internal components — cylinder heads, valve train components, and much of the rotating assembly are common or closely related between the two.

The Key Differences

1. Oil System — The Defining Distinction

M177: Wet Sump The M177 uses a conventional wet sump oil system. Oil is stored in a pan bolted to the bottom of the engine block. A single oil pump draws oil from the sump and circulates it through the engine.

Simpler design, fewer components
Slightly taller engine package (the sump adds height below the crankshaft centerline)
Susceptible to oil starvation during sustained high-G cornering (hard left/right turns, aggressive track driving can uncover the oil pickup)

M178: Dry Sump The M178 uses a dry sump oil system with an external oil reservoir. Instead of storing oil in a pan beneath the engine, a two-stage scavenge pump continuously evacuates oil from the crankcase and stores it in a separate tank. A pressure pump then feeds oil from the tank to the engine.

Oil capacity: Approximately 12 liters in the external tank (vs. ~8-9 liters total in the M177 wet sump system)
Scavenge pump capacity: 250 liters per minute
Allows a lower engine mounting position (no deep oil pan needed)
Immune to oil starvation during sustained lateral G-forces — critical for the AMG GT's sports car mission
More complex, heavier system overall (pumps, tank, additional lines), though the engine itself sits lower, improving center of gravity

2. Engine Mounting and Physical Dimensions

The dry sump system on the M178 allows the engine to sit lower in the chassis. In the AMG GT, the engine is mounted as far back and as low as possible — a front-mid-engine layout that contributes to the GT's 47/53 front/rear weight distribution.

The M177 doesn't need to sit as low. It's packaged conventionally in the engine bay of sedans, SUVs, and crossovers where maximum low-CG mounting isn't the priority.

3. Exhaust and Turbo Geometry

Both engines place the turbos in the hot-V, but the exhaust manifold routing differs slightly:

M177: Exhaust manifolds route from the cylinder heads inward and upward to the centrally mounted turbos. The exhaust then exits downward through the transmission tunnel area. Packaging is dictated by the various chassis it fits (C-Class through GLS, plus G-Class).

M178: The AMG GT's dedicated sports car chassis allows for more optimized exhaust routing. The exhaust path is shorter and less restrictive, contributing to slightly better turbo response and more aggressive exhaust tuning. The M178's exhaust system is also tuned for a different sound character — sharper, more race-oriented compared to the M177's deeper, more refined tone in most applications.

4. Cooling Layout

M177: Cooling system is adapted to fit each host chassis. The charge cooler heat exchangers, radiator, and associated plumbing are designed to work within the packaging constraints of each model (C-Class is tighter than E-Class, which is tighter than GLE, etc.).

M178: The AMG GT's purpose-built chassis allows for a dedicated cooling layout. The M178 has more aggressive factory cooling — larger heat exchangers and more direct airflow paths to the cooling components. The GT R and GT Black Series variants have additional factory cooling upgrades.

5. Power Outputs

The M177 and M178 are tuned to different power levels across their respective applications:

M177 Power Outputs (Factory):

Model	Power	Torque
C63 (W205)	469 HP (350 kW)	479 lb-ft (650 Nm)
C63 S (W205)	503 HP (375 kW)	516 lb-ft (700 Nm)
E63 (W213)	563 HP (420 kW)	553 lb-ft (750 Nm)
E63 S (W213)	603 HP (450 kW)	627 lb-ft (850 Nm)
G63 (W463)	577 HP (430 kW)	627 lb-ft (850 Nm)
GLC63 S	503 HP (375 kW)	516 lb-ft (700 Nm)
GLE63 S	603 HP (450 kW)	627 lb-ft (850 Nm)
GLS63	603 HP (450 kW)	627 lb-ft (850 Nm)
GT 63 S 4-Door (X290)	630 HP (470 kW)	664 lb-ft (900 Nm)

M178 Power Outputs (Factory):

Model	Power	Torque
AMG GT (C190)	462 HP (340 kW)	443 lb-ft (600 Nm)
AMG GT S	510 HP (375 kW)	479 lb-ft (650 Nm)
AMG GT C	557 HP (410 kW)	502 lb-ft (680 Nm)
AMG GT R	577 HP (430 kW)	516 lb-ft (700 Nm)
AMG GT R Pro	577 HP (430 kW)	516 lb-ft (700 Nm)
AMG GT Black Series	720 HP (537 kW)	590 lb-ft (800 Nm)
AMG GT Track Series	734 HP (540 kW)	627 lb-ft (850 Nm)

Note: The AMG GT Black Series and Track Series use a significantly modified version of the M178 with a flat-plane crankshaft — designated M178 LS2 — which is effectively a different engine from the standard M178.

Which AMGs Get Which Engine — The Complete List

M177 (Wet Sump) — Sedans, SUVs, 4-Door GT

Mercedes-AMG C63 / C63 S (W205, 2015-2021)
Mercedes-AMG E63 / E63 S (W213, 2017+)
Mercedes-AMG S63 (W222, C217, 2017+)
Mercedes-AMG G63 (W463, 2018+)
Mercedes-AMG GLC63 / GLC63 S (X253/C253, 2017+)
Mercedes-AMG GLE63 / GLE63 S (W167, 2020+)
Mercedes-AMG GLS63 (X167, 2020+)
Mercedes-AMG GT 63 / GT 63 S 4-Door (X290, 2019+)

Also used in (M177 variant):

Aston Martin Vantage (2018+)
Aston Martin DB11 V8 (2017+)
Aston Martin DBX (V8 variant)

M178 (Dry Sump) — 2-Door Sports Cars

Mercedes-AMG GT (C190, 2014+)
Mercedes-AMG GT S (C190, 2014+)
Mercedes-AMG GT C (C190, 2017+)
Mercedes-AMG GT R (C190, 2017+)
Mercedes-AMG GT R Pro (C190, 2019+)
Mercedes-AMG GT Black Series (C190, 2020)
Mercedes-AMG GT Track Series (C190, 2022)

The simple rule: If it's a 2-door AMG GT (C190), it's the M178 (dry sump). Everything else in the AMG lineup — plus the Aston Martin V8 models — uses the M177 (wet sump).

Tuning Differences

M177 Tuning Characteristics

The M177 is the more commonly tuned of the two engines, primarily because it's in more cars and those cars are generally less expensive.

Advantages for tuning: - Larger aftermarket support — more tuners, more parts, more data - The 9-speed MCT transmission in the E63/G63/GLE63 has strong torque capacity - Easier to work on in most chassis (the C63 is tight, but the E63 and G63 have more space) - Lower starting power on some variants (C63 base at 469 HP) means more headroom before reaching hardware limits

Typical tuning stages (M177): - Stage 1 (ECU tune only): 600-650 WHP - Stage 2 (downpipes, intake, tune): 700-800 WHP - Stage 3 (turbo upgrade, fuel system): 800-1,000+ WHP

M178 Tuning Characteristics

The M178 responds to tuning similarly to the M177 in most respects — same displacement, same compression, same basic turbo setup. But there are meaningful differences:

Advantages for tuning: - Dry sump oil system handles high-G track use without starvation concerns - More aggressive factory cooling on higher-spec variants (GT R, GT C) - The AMG GT is lighter than M177-equipped sedans and SUVs, so the same power level produces a faster car

Challenges for tuning: - Smaller aftermarket than the M177 — fewer tuners specialize in the M178 - The AMG GT's rear-mounted transaxle transmission (7-speed dual-clutch on later variants) is a different unit than the M177's transmissions, requiring different TCU calibrations - Engine access is more difficult in the AMG GT's long-hood, front-mid-engine layout - The dry sump system adds complexity for engine-out work

Typical tuning stages (M178): - Stage 1 (ECU tune only): 550-620 WHP - Stage 2 (downpipes, intake, tune): 650-750 WHP - Stage 3 (turbo upgrade, fuel system): 800-1,000+ WHP

The M178's slightly lower Stage 1 and Stage 2 numbers compared to the M177 reflect the different turbo configurations and exhaust routing rather than any fundamental engine weakness.

Parts Compatibility

What's interchangeable: - Many internal engine components (pistons, rods, bearings, valve train) are identical or closely related - Turbocharger cartridges and rebuild kits are often the same - Fuel system components (injectors, fuel rail) share specifications - Spark plugs and ignition coils are the same

What's NOT interchangeable: - Oil pan / sump assembly (fundamentally different systems) - Oil pump and scavenge pump assemblies - Engine mounts and mounting hardware (different chassis, different mounts) - Exhaust manifolds (different routing for different chassis) - Transmission and TCU (completely different units) - Intake manifold (may differ depending on specific variant) - Engine wiring harness (chassis-specific)

Common Confusion Points

"The M177 has a flat-plane crank"

Not standard. The production M177 and standard M178 use a cross-plane crankshaft. The flat-plane crank is used only in the M178 LS2 variant found in the AMG GT Black Series and GT Track Series. There have been reports of an M177 Evo variant with a flat-plane crank, but this is not in widespread production M177 applications as of 2026.

"The M178 is just an M177 with a dry sump"

Partially true but misleading. The oil system difference is the most significant distinction, but the engines also differ in exhaust manifold design, cooling layout, engine mounting, and in some cases turbo configuration. They're siblings, not twins.

"You can swap an M178 into an M177 car (or vice versa)"

Theoretically possible but rarely practical. The oil system, engine mounts, wiring harness, and transmission are all different. The swap requires extensive fabrication. There's no performance reason to do it — both engines respond to the same tuning modifications with similar results.

"The AMG GT 4-Door uses the M178"

No. The GT 4-Door (X290) uses the M177 with a wet sump. Despite the "GT" name, it's architecturally an M177 car. The "GT" designation in 4-door form refers to the vehicle platform, not the engine variant.

Bottom Line

The M177 and M178 are branches of the same family tree — same displacement, same bore and stroke, same hot-V turbo layout. The M178's dry sump oil system is the headline difference, purpose-built for the AMG GT's sports car mission. For tuning, both engines respond similarly and share many internal components. The M177 has a significantly larger aftermarket due to its wider deployment across the AMG range. Understanding which engine your car has matters for parts compatibility, tuner selection, and oil system maintenance — but from a pure power potential standpoint, both engines are capable of 1,000+ WHP with the right modifications. Shops like YPG Motorsport tune both the M177 and M178 platforms and can advise on the specific differences that matter for your build.

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