M177 vs M178 AMG Engine Comparison
M177 vs M178 — AMG 4.0T V8 Engine Comparison
Mercedes-AMG's 4.0-liter twin-turbo V8 comes in two variants: the M177 and the M178. They share the same basic architecture — 4.0L displacement, twin-scroll turbochargers in a hot-V configuration, and hand-built "one man, one engine" assembly — but differ in critical ways that affect performance, tuning potential, and application. Understanding the differences is essential when choosing parts, calibrations, and build paths.
For the complete M177 spec sheet, known issues, and full build path from Stage 1 to 1,500 HP, read our M177 Complete Engine Guide.
Technical Comparison
| Specification | M177 | M178 |
|---|---|---|
| Displacement | 3,982 cc | 3,982 cc |
| Crankshaft | Cross-plane (90° firing order) | Flat-plane (180° firing order) |
| Oiling System | Wet sump | Dry sump |
| Factory HP Range | 469–630 HP | 476–730 HP |
| Rev Limit | ~6,500–7,200 RPM | ~7,200–7,600 RPM |
| Character | Deep V8 rumble, massive low-end torque | Higher-pitched, sharper, more rev-happy |
| Mounting | Front-longitudinal in standard chassis | Front-mid, lower center of gravity |
| Applications | C63, E63, GT63, GLC63, G63, GLE63 | AMG GT, GT R, GT S, GT C, GT Black Series |
| YPG Crate Engine | From $29,999 | From $35,000 |
Flat-Plane vs Cross-Plane Crank
The most significant difference between the M177 and M178 is the crankshaft. The M177 uses a conventional cross-plane crank that produces the classic V8 burble and delivers massive torque from low RPM. The M178's flat-plane crank fires the cylinders in an even left-right-left-right sequence, creating a sharper, higher-pitched exhaust note and enabling the engine to rev higher and breathe more efficiently at the top of the RPM range.
The flat-plane design also reduces rotational inertia, allowing faster throttle response and quicker spool — but it introduces more secondary vibration, which is why Mercedes pairs the M178 with a dry-sump oiling system and reinforced engine mounts in the dedicated AMG GT sports car platform.
Tuning Differences
Both engines respond exceptionally well to ECU tuning, but the calibration approach differs:
- ▸ M177: Huge torque gains in the midrange. Stage 1 tunes unlock 80–100 HP. The cross-plane crank loves boost. With forged internals and turbo upgrades, 800+ WHP builds are proven — including our 828 WHP world record C63.
- ▸ M178: More top-end focused gains. The flat-plane crank rewards high-RPM calibrations. Stage 1 tunes unlock 60–80 HP. Stage 2+ with downpipes opens up significantly more. The dry-sump system handles sustained high-g loads better for track use.
Which Engine is Better for Tuning?
The M177 offers more accessible, higher-magnitude gains — especially at Stage 2 and Stage 3 where the cross-plane crank's torque characteristics pair perfectly with bigger turbos. It's also more widely available, with parts and calibrations well-established across multiple chassis.
The M178 shines on track where the flat-plane crank's higher rev ceiling and the dry-sump oiling system provide advantages under sustained lateral and longitudinal g-forces. For pure drag racing, the M177 is typically preferred; for circuit racing, the M178 has inherent advantages.
Build Both Platforms With YPG
YPG Motorsport builds forged M177 crate engines from $29,999 and M178 crate engines from $35,000 — both rated to 1,500 HP with CP-Carrillo forged internals, ported race heads, and ARP hardware. No core exchange. Ships worldwide.
For the full lineup including the M156 6.2L NA V8, visit our AMG Crate Engines hub.