When it comes to legendary engines in the high-performance world, the Mercedes-Benz M156 6.2-liter V8 is a standout. Built by AMG to power models like the C63 AMG, E63 AMG, G63, ML63, CLS63 and SL63 AMG, this engine is beloved by enthusiasts for its great power delivery, high-revving nature, and strong potential for performance upgrades and lets not forget, the incredible sound it make.
In this post, we’ll dive into the strengths of the M156, why it has earned such a great reputation, and explore how aftermarket modifications such as long tube headers and performance ECU tuning can take this engine’s performance to new heights. Whether you’re a C63 AMG owner looking to improve your AMG performance or simply want to learn more about what makes the M156 special, read on.
1. Power and Torque
Right out of the factory, the M156 delivers serious performance. With outputs ranging from 451 hp to 518 hp (depending on the model) and 443 to 465 lb-ft of torque, it brings a level of power that is hard to beat for the money. The best part? The linear power delivery . Nothing beats a high hp naturally asperated V8. The instant power delivery is heard to beat. Although We do all love all the Biturbo Mercedes as well.
2. High-Revving
The M156 has a 7,200 RPM redline, which is unusually high for a V8 of this size. This high-revving characteristic makes it an engine that loves to be pushed hard, delivering maximum performance and excitement at the upper end of the RPM range
3. Built to Last (kind of)
AMG didn’t just focus on power; they made sure the M156 was built to withstand extreme performance conditions. With a closed-deck aluminum block, forged crankshaft, and other lightweight components, the M156 is engineered for durability. This makes it the perfect foundation for performance modifications, allowing it to handle increased power without breaking a sweat.
We cant forget that the M156 engine is not without its problems over the years. I was around at the launch of the M156 in car like the C63 and W211 E63 AMG's. The most notable problem early owners of the Mercedes AMG's equipped with the M156 engine was the head stud issue. This was literally destroying engines. What would happen is the head bolts would stretch or even crack and this would cause coolant to yet into the combustion chamber and thats not a good thing at all! It look s like all M156 engine would be affected by the head stud issue up to year 2012, However I had a 2010 C63 and did not have head stud problems. Funny when I purchased my W204 C63 a tech at the dealer I worked with told me I should be good with the head studs since my car was a 2010. So it seemed Mercedes really didnt have a grasp on the head stud issue since it effected M156 powered AMG's past 2010. I did have a stuck lifter on my C63, but that was a quick fix under warranty at the time.
Valve buckets is another issue, The cam lobes ride over the valve buckets or tappets and it can literally wear a hole in your valve tappets. Then there was the cam adjusters that problem that could be noticed on cold starts with a rattle. I could go into detail on all of this, but you would think this blog was an M156 bash fest. When its not, The M156 engine is great. But like all engines it had/has some bugs that needed/need to be worked out.
4. A Platform for Tuners
The M156’s sturdy construction and naturally aspirated nature make it a fantastic platform for tuning. Many aftermarket companies offer solutions that can significantly enhance the engine’s performance, including long tube headers, performance ECU tuning, all the way to supercharger systems. Most M156 equipped AMG are well supported in the aftermarket.
Performance You Can Feel
Driving a car with the M156 engine is a truly engaging experience. The linear power delivery means that power builds smoothly as you climb through the revs, making it easy to control and predict during aggressive driving or on the track. And let’s not forget about the sound—the M156’s throaty V8 roar is one of its signature traits, adding to the overall thrill of the drive.
Popular Aftermarket Modifications for the M156
If you’re looking to take your AMG’s performance to the next level, there are several aftermarket modifications that can unleash even more power from the M156 engine. Let’s explore a few of the most popular options.
Long Tube Headers
One of the best upgrades for the M156 is long tube headers. These headers replace the restrictive factory exhaust manifolds, improving exhaust flow and unlocking significant performance gains. M156 Long tube headers allow the engine to breathe more freely, resulting in more power and a more aggressive exhaust note.
Performance Gains:
Horsepower increase: 35-45 hp. over stock (no other mods)
Improved torque: Enhanced mid-range torque.
Better sound: The headers produce a deeper, more aggressive exhaust tone.
This graph shows the potential horsepower gains with long tube headers installed,
As you can see, the power curve of the M156 builds smoothly all the way to the redline, offering consistent performance across the RPM range.
Performance ECU Tuning
To complement mechanical upgrades like long tube headers, performance ECU tuning is an essential step. ECU tuning involves optimizing the engine’s fuel mapping and ignition timing,. A properly tuned ECU can unlock more horsepower and torque, as well as sharpen the car’s overall performance without causing reliability issues. .
Performance Gains:
Horsepower increase: can get over 100+ wheel horsepower over stock, depending on the tune and other modifications.
Enhanced throttle response: Quicker, more immediate acceleration.
Improved torque: Increased low-end and mid-range performance.
2015 C63 AMG 507 Edition Dyno chart. MBH headers and tuning
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Tuning Your M156: What You Can Expect
When tuning your M156 equipped AMG, its important to get on a load based dyno like a Dyno Dynamics brand dyno for example. This way you can tune part throttle while the engine is under load, rather than just spinning a large drum that gets easier to spin once it is moving. With tuning there is no magic wand, if the tuner you use is good and the tune file loaded onto your ECU is good that most tunes from one tuner to another should be about the same in the end. Unfortunately its not always like that and some tuners are just have better maps and are more skilled.
Don't be disappointed if your dyno numbers from baseline to end result are lower than some others guys. If your car dynos at 360whp for a base like on a Dyno Dynamics but you have seen baselines of 400+ whp from other people, don't worry about that. Lots of factors come into play when showing power numbers.
Stock M156 C63 AMG's do not open the throttle body all the way like other M156 AMG's Mercedes wanted the more expensive models to have the most horsepower so the C63 was "detuned" from the factory. This is why C63's can see a massive power gain over stock when tuning is added. Simply because the new tune file loaded on your C63 is allowing the throttle bodies to open up all the way along with increased timing and revised fuel mapping and ignition. So yes gaining 100-120+ hp on a C63 AMG is possible when you do custom tuning paired with our long tube headers.
The M156 equipped AMG's have become widely popular. The intoxicating sound from a modified M156 AMG is something to behold as well as its robust constriction it makes for of the best German made engines as well as a great platform for someone to modify as well.
Let me know what you think of the M156 engine? did you have any problems? What mod did you do or are you going to do?
If you are looking to take your M156 to the next level we support a wide range of cars fitted with the M156 engine. Below are some
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