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M157

M278 & M157: Real Upgrades That Deliver

The twin-turbo V8 era rewarded simple, proven mods: better cooling, tidy airflow, clean calibration. Skip gimmicks—do the work that actually moves the needle.

M278 (4.7L V8 Biturbo)

The M278 responds best to heat control and backpressure reduction. Keep intake temps in check and let the turbos breathe; the ECU will do the rest with a proper tune.

Common Platforms

  • E550 (W212)
  • CLS550 (W218)
  • S550 (W221/W222 early)
  • CL550 (C216)
  • GL/GLS 550 (X166)
  • ML/GLE 550 (W166)

Upgrades That Matter

  1. Front-Mount Heat Exchanger (FMHE) – Increases thermal capacity and slows heat soak during spirited pulls.
  2. Auxiliary Heat Exchanger – Stabilizes IATs after back-to-back runs; pairs with FMHE for consistent charge temps.
  3. High-Flow Intercooler Pump – Improves coolant circulation through the charge-cooler loop for steadier temps.
  4. Downpipes (track/off-road) – Reduces turbine outlet pressure; improves transient response and mid-range torque when tuned.
  5. Intake & Inlet Refinements – Keep it simple: quality filters and sealed ducting reduce turbulence without hot air creep.

Tuning Notes

Strong results come from cooling + calibration. Don’t chase peak numbers on a heat-soaked pull; build for repeatability and you’ll feel the difference every drive.

M157 (AMG 5.5L V8 Biturbo)

The M157 is stout and rewards a measured, old-school approach: control heat, shorten pressure drop, then ask the tune for more—reliably.

Common Platforms

  • E63 AMG (W212)
  • CLS63 AMG (W218)
  • S63 AMG (W221/W222 early)
  • CL63 AMG (C216)
  • ML/GL/GLE/GLS 63 AMG (W166/X166)
  • G63 AMG (W463 pre-M177)

Upgrades That Matter

  1. Oversized FMHE – Larger core for the higher AMG heat load; keeps timing intact through long pulls.
  2. Aux Heat Exchanger & Hard-Line/Manifold Cleanup – Smooth flow, faster recovery between hits.
  3. High-Output Intercooler Pump – Supports continuous charge-cooler circulation under sustained load.
  4. Downpipes (track/off-road) – Frees the turbos; helps spool and extends the usable powerband with the right map.
  5. Thermal Management – Heat shielding, fresh plugs, healthy coils; simple maintenance prevents false knock and timing pull.

Tuning Notes

Build for repeatable performance, not a one-and-done dyno hero run. Keep IATs in line, verify fuel quality, then lean on the torque where these cars live—mid-range.

FAQ

Do I need both FMHE and an auxiliary unit?
If you do repeated pulls or drive in heat, yes. The combo slows heat soak and keeps power consistent.
Will these parts affect emissions or inspection?
Cooling hardware is typically fine. Downpipes are for off-road/track use where allowed. Know your local laws.
What’s the smartest first step?
Start with cooling (FMHE + pump). Then tune. Add downpipes only if your use-case and local regulations allow.