Mercedes M278 vs M157: Key Differences and Which Engine Suits You Best. mercedes m278 engine for sale

If you’re looking to purchase replacement engines for your Mercedes-Benz or provide your ride with a shot in the performance arm, then there are two V8 giants you’ve likely considered: the Mercedes M278 and the AMG M157. Both engines have left their marks on the fields of reliability, refinement, and sheer output — though each was engineered with differing aspirations in mind.

In today’s post, we’re pitting the M278 vs M157 engine reliability and power, price and availability, and more. And most importantly, we’ll give you a conclusion to choose the ideal engine for you — and where you can buy either engine from a reliable source. mercedes m278 engine for sale

Introduction to M157 and M278 Engines
Mercedes M278 Engine Overview
Mercedes M157 Engine Review
M278 vs M157: Key Specifications Comparison
Performance Differences
Reliability and Maintenance
Fuel Efficiency Comparison
Applications: Which Mercedes Use These Engines?
Tuning Potential and Aftermarket Support
Pricing and Availability
Which Engine Is Best for You?
Where to Buy Mercedes M278 and M157 Engines
Final Considerations mercedes m278 engine for sale

1. Introduction to the M278 and M157 Engines

Mercedes-Benz produces cars that are a combination of luxury, performance, and technology. At the heart of the majority of its luxury vehicles is the M278 or the M157 — twin-turbo V8s that couldn’t be more different. mercedes m278 engine for sale

M278: A power-conscious but efficiency-focused engine used in most non-AMG luxuries.
M157: A high-performance, AMG-tuned beast designed for exciting driving dynamics. mercedes m278 engine for sale

In the event that you require a good donor engine or wish to upgrade to AMG performance, it’s good to know the difference between these two motors. mercedes m278 engine for sale

2. Overview of Mercedes M278 Engine

Mercedes M278 is a 4.6L twin-turbo V8 engine introduced in 2011 as a substitute for the previous naturally aspirated M273. The new engine was designed to produce more power and torque but was also intended to provide improved fuel efficiency and emissions.

Key Specs: mercedes m278 engine for sale

Displacement: 4.6L (4663 cc)
Configuration: V8, DOHC, 32-valve
Forced Induction: Twin-turbocharged
Horsepower: 402-455 hp (model/year dependent)
Torque: 443–516 lb-ft
Fuel System: Direct Injection
Valvetrain: Dual overhead camshaft (DOHC) with variable valve timing

The M278 powers a number of Mercedes sedans, coupes, and SUVs in the S-Class, E-Class, GL-Class, and CLS-Class. mercedes m278 engine for sale

3. Mercedes M157 Engine Overview

The Mercedes-AMG M157 is the high-performance variant of the M278, hand-assembled by AMG engineers. The M157, being of greater displacement and more aggressive tuning, is designed for power, luxury, and performance. mercedes m278 engine for sale

Key Specs:

Displacement: 5.5L (5461 cc)
Configuration: V8, DOHC, 32-valve
Forced Induction: Twin-Turbocharging
Horsepower: 518–577 hp (year and trim specific)
Torque: 516–664 lb-ft
Fuel System: Direct Injection
Valvetrain: DOHC variable valve timing

The M157 is probably used in Mercedes automobile AMG models such as the E63 AMG, S63 AMG, ML63 AMG, GL63 AMG, and CLS63 AMG. mercedes m278 engine for sale

4. M278 vs M157: Key Specifications Compared

Feature	M278 Engine	M157 Engine
Displacement	4.6L	5.5L
Turbochargers	Twin	Twin
Horsepower	402–455 hp	518–577 hp
Torque	443–516 lb-ft	516–664 lb-ft
Fuel Type	Premium	Premium
Application	Standard luxury	High-performance AMG

The M157 appears to be stronger but is also more expensive to fuel and maintain.

5. Differences in Performance

The M278 accelerates smoothly from the line and cruises down the highway with ease. It’s perfect for owners of luxury vehicles who prefer subtle, refined power. The M157 is track-ready, however. Its aggressive turbo configuration and high torque output make it well-suited to driving enthusiasts and speed freaks.

0–60 mph times:

M278: ~4.9–5.2 s (depending on the model)
M157: ~3.8–4.3 seconds

6. Maintenance and Reliability

Both of these motors are new, current, and durable but are only as reliable as you make them based on use and maintenance.

M278 Reliability

Common Issues: Timing chain stretch, camshaft adjuster failure, oil leak
Maintenance Cost: Medium
Longevity: Long-lasting, survives more than 200,000 miles with proper maintenance mercedes m278 engine for sale

M157 Reliability

Common Issues: Turbo oil seals, head bolts, intercooler leaks
Maintenance Cost: High (performance & labor parts)
Longevity: Needs careful attention but is long-lasting if properly cared for

When buying a remanufactured or rebuilt engine, buy from an authorized dealer with warrantied and inspected engines.

7. Fuel Efficiency Comparison

M278: ~18–22 MPG combined
M157: ~15–18 MPG combined

If economy is paramount, the M278 is more economical. If raw performance is more important than MPG, then the M157 wins out. mercedes m278 engine for sale

8. Applications: Which Mercedes Models Use These Engines?

M278 Applications:

Mercedes-Benz S550 (W221, W222)
E550 (W212)
CLS550
GL550
SL550

M157 Applications:

Mercedes-AMG S63
E63 AMG
CLS63 AMG
GL63 AMG
ML63 AMG
G63 AMG (earlier models prior to M177)

If your vehicle was originally equipped with an M278 or an M157, buying the same kind of engine will assure compatibility. mercedes m278 engine for sale

9. Potential Tuning and Aftermarket Support

M278: Not straightforward to tune due to conservative ECU settings and internals that are not exactly friendly towards high degrees of performance boost.
M157: Highly tunable with bolt-ons, remaps, and turbo upgrades — most make 700+ hp.

If you must tune your automobile, then the M157 is the perfect platform.

10. Price and Availability

We stock warranted and tested quality remanufactured and used M278 and M157 engines in our engine shop.

Sample Price:

M278 engines: $4,800 USD and above
M157 engines: $6,500 USD and above

Mileage, condition, and warranty requirement-based pricing. Availability and quotes on call.

11. Which Engine Is Right for You?

Choose the M278 when:

You want performance and luxury
You’re installing a non-stock engine into a non-AMG car
You’d rather have less maintenance cost

Choose the M157 if:

You need class-leading performance
You’re restoring or reconstructing an AMG car
You need space for tuning for more horsepower

We carry both engines in our shop and can help you decide which would work best for your car and driving.

12. Where to Purchase Mercedes M278 and M157 Engines

We offer remanufactured and used Mercedes engines, such as:

Mercedes-Benz M278 engines
High-performance AMG M157 engines
Compression- and leakdown-tested engines
Warranted engines
Low shipping charge

You don’t purchase an engine — you purchase peace of mind. You’re a shop owner, a mechanic, or an enthusiast, and we have the part and service that you require.

Ready to buy your Mercedes M278 or M157 engine? Call us today.

13. Final Thoughts

Mercedes’ M157 and M278 engines each have their own unique appeal to offer. The M278 is a daily luxury and comfort master, and the M157 offers AMG performance excitement and dynamics.

Some way, somehow, whatever engine you need, we can provide you with a quality warrantied engine at the right price. Shop our inventory, consult with a technician, or shop online today.

Your next engine starts here.

Mercedes M278 vs M157: Key Differences and Which Engine Is Right for You? Mercedes M278 Engine For Sale