Mercedes M156 Tuning

"All you need to know about performance tuning the Mercedes M156 engine!"

TorqueCars will review M156 tuning and highlight the premier mods that work. Mercedes M156 are popular tuning projects and with carefully chosen uprated upgrades like a remap, turbo kits and camshafts you will certainly increase your driving experience.

History, Power & Specs of the M156 Engine


  • 475 hp 482 PS 354 kW at 6,800 rpm 630 Nm 465lbft @ 5,200 rpm.
  • 2007 CLS63 and E63, 507 hp 514 PS 378 kW at 6,800 rpm 630 Nm 465lbft at 5,200 rpm
  • 2007 ML63 503 hp 510 PS 375 kW
  • 2008 C63  451 hp 457 PS 336 kW
  • 2015 C63  500 hp 507 PS 373 kW

Tuning the Mercedes M156 and best M156 performance parts.

Best M156 modifications

Just because particular modifications are popular with M156 owners it doesn't mean you should fit it, instead we'll optimum modifications that will give your M156 the best value for money to power increase.

Altering your M156 camshaft will make a dramatic difference to the engine bhp. Choosing a higher performance camshaft profile raises the bhp accordingly.

Fast road camshafts normally raise the bhp and torque across the rev range, you may sacrifice a little low down bhp but your higher rpm power will be lifted.

Competition camshafts, raise the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport cam will just annoy you whilst driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

You should ideally optimize your torque band to your driving style so for a daily driver stick with a mild fast road M156 cam

Some M156 engines respond better to less aggressive camshaft durations so set your engine up on a rolling road.

The engine timing and fuel pump and injectors also have a large bearing on the torque gains you'll get.

Longer valve durations can alter the torque band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

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Best Engine Mods for your car

  1. Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.
  6. Typical stage 1 mods often include:
    Sports exhaust header/manifold, drilled & smoothed airbox, Panel air filters, Remaps/piggy back ECU, Intake manifolds, Fast road camshaft.

    Typical stage 2 mods often include:
    Fast road cam, fuel pump upgrades, Ported and polished head, induction kit, high flow fuel injectors, Sports catalyst & performance exhaust.

    Typical stage 3 mods often include:
    Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Adding or Upgrading forced induction (turbo/supercharger), Competition cam, Crank and Piston upgrades to alter compression, Twin charging conversions.

    The M156 engine blocks respond well to mods and we note that there is a lot of modifications and performance parts about.

    Remaps will help to establish the full potential of all the tuning mods you've done to your M156.

    (In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

    It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but your results usually vary depending on the tuning mods you've applied and the condition of your engine.

    It is vital to any tuning task to shove more fuel and air into the M156 engine

    Intake manifold carry the air during the suck phase from the filter and allow it to be drawn into the engine cylinders.

    Design and flow rate of the Plenum can make a substantial change to fuel mixing and power on the M156.

    On popular production engines plenum chambers are improved through motorsport parts, although some manufacturers provide well optimised plenum chambers.

    Adding a M156 larger valve kit, getting port work and head flowing will also raise torque, and importantly will afford you an improved torque increase on other upgrades.

    M156 Turbo upgrades

    NA (naturally aspirated) engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your M156

    The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes excellent power gains.

    When an engine has forced induction parts are more reliable and you'll see that turbo engines are built using many forged and stronger components.

    There are practical limits for every engine, with some being extremely strong and some only able to handle stock powerIt is important to find these limits and fit better quality components to survive the power.

    We've seen drivers spending a loads of money on turbocharger upgrades on the M156 only to have the engine block explode when it's been completed.

    Larger upgraded turbo chargers will usually suffer low end lag, and little turbo chargers spool up more quickly but won't have the high rpm bhp gains.

    In the last 10 years the world of turbo chargers is always developing and we now see variable vane turbo chargers, permitting the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

    Twin scroll turbo chargers divert the exhaust gases into 2 channels and flow these at differently designed vanes in the turbo. They also increase the scavenging effect of the engine.

    You'll commonly see there is a limit in the air flow sensor MAF/MAP on the M156 when considerably more air is being pulled into the engine.

    Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting power at a much lower level.

    Adding a supercharger or additional turbo will make large power gains, although more challenging to configure. We have this feature on twinchargers if you want to read more.


    Don't forget to raise the fuel delivery when you are increasing the torque - it makes the car more thirsty. We strongly recommend you to over specify your flow rate on the injectors.

    The accepted safe increase is to add another 20% when specifying an injector, this allows for injector deterioration and provides some spare capacity should the engine require more fuel.

    We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

    M156 Performance Exhausts

    You may need to uprate your exhaust if the current exhaust is actually creating a restriction.

    On most factory exhausts you'll see the exhaust flow rate is still ok even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

    Sports exhausts balance the flow of air through the engine.

    But if the exhaust is too big, ie: over 2.5 inches bore, you will lose much of your flow rate and end up losing power and torque.

    Typically exhaust restrictions come around the emissions filters installed, so adding a better flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

    Weak spots, Issues & problem areas on the M156

    The M156 engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

    Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

    Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

    Regular oil changes are vital on the M156, especially when tuned and will help extend the life and reliability of the engine.

    If you would like to know more, or just get some friendly advice on Tuning your M156 engine please join us in our car forums where you can discuss M156 tuning options in more detail with our M156 owners. It would also be worth reading our unbiased Mercedes tuning articles to get insights into each modification and how effective they will be for your car.

    Please help us improve these tips by sending us your feedback in the comments box below.

    We love to hear what our visitors have got up to and which modifications work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these M156 tuning guides which get regular updates and revisions.

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