Mercedes M137 Tuning

"All you need to know about performance tuning the Mercedes M137 engine!"

The M137 is phenomenal, an amazing V12 block.

The base 5.8 litre engine pushed out 362hp, and AMG got their hands on it pushing the power up further to 437hp, showing the flexibility and potential of this block.

Both M137 versions will still offer gains when tuned properly, through careful selection of cam profiles, head work, increasing the cylinder capacity and carefully setting up the mapping.

V12 engines like the M137 were not designed to be high revving monsters, instead they deliver shed loads of torque at the low end, and this should be your aim when tuning it.

Raise the torque and power bands rather than extending it.

This pages aim is review M137 tuning and report on the premier mods that work.

History, Power & Specs of the M137 Engine

M137 E58

367 PS 362 hp at 5500 rpm and torque figures of 530 Nm 391lbft at 4250 rpm

  • 1998–2002 S 600
  • 1998–2002 CL 600

M137 E63 AMG

443 PS 437 hp at 5500 rpm and torque figures of 620 Nm 457lbft at 4400 rpm

  • 2001 S 63 AMG
  • 2001 CL 63 AMG
  • 2002 G 63 AMG

The M137 was replaced with a turbocharged unit the M275

Tuning the Mercedes M137 and best M137 performance parts.

Best M137 parts

Just because particular upgrades are are common on M137 it doesn't mean you should fit it, so we'll best upgrades that will give your M137 the best power gain for you money.

The cam profile plays a big part in the engines power output so cam upgrades make quite a large difference. The intake and exhaust durations will alter depending on the chosen cam profile, so large bhp gains are on offer for cam upgrades.

Fast road cams tend to increase the bhp and torque over the rev band, you may sacrifice a little low end torque but the high end rpm power will be higher.

Motorsport cams, increase the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport and race camshaft won't do well if driving in heavy traffic.

You should ideally match your engines power to your preferences so for a daily driver stick with a fast road M137 camshaft

Different M137 engines respond better to different camshaft durations than others.

The engine timing and fuelling also will say much on the bhp gains you'll achieve.

Extending exhaust or intake durations can alter the bhp 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:
    Fast road camshaft, drilled & smoothed airbox, Remaps/piggy back ECU, Intake manifolds, Panel air filters, Sports exhaust header/manifold.

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

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

    Carefully think through your options and then buy your tuning parts and set yourself a power target to avoid disappointment.

    ECU flashing should help to establish the full potential of all the tuning parts you've done to your M137.

    (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 the outcome usually rely on the tuning parts you've carried out and the condition of your engine.

    It is vital to any engine upgrade project to get air and fuel into the M137 engine

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

    Structure and flow rate of the Intake manifold can make a substantial difference to fuel atomisation on the M137.

    It's not uncommon that plenum chambers are ripe for an upgrade, although some manufacturers provide reasonably good plenum chambers.

    Increasing the M137 valve size, doing some port matching and head flowing will also lift bhp and torque, and as an added benefit will afford you a better bhp and torque increase on other mods.

    M137 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 M137

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

    When an engine is fitted with a turbocharger modifications are more reliable and you'll see that turbo engines are built with stronger components.

    There are reliable limits for every engine, with some being incredibly solid and some only able to handle stock powerDiscover these restrictions and install stronger pistons, crank and engine components to cope with the power.

    We've seen tuners spending a loads on turbo charger upgrades on the M137 only to suffer the indignity of watching the car throw a rod when it's finished.

    Bigger upgraded turbochargers tend to experience no power at low rpm, and low capacity turbochargers spool up much more quickly but won't have the peak end engines power gains.

    Over the last 20 years the choice of turbo units is always increasing and we now see variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end power.

    Twin scroll turbo units divert the exhaust gases into a couple of channels and direct these at differently profiled vanes in the turbo. They also boost the scavenging effect of the engine.

    You'll commonly see there is a limit in the air flow sensor MAP/MAF/AFM on the M137 when loads more air is being drawn 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 torque at a much lower level.

    Adding a supercharger or additional turbo will make large bhp and torque gains, although more difficult to configure. We have this article on twincharging if you want to read more.


    When you raise the bhp you will need to uprate to the fuel system.

    More bhp needs more fuel. It makes sense to over specify your injectors flow rate.

    The rule of thumb is to add 20% to the flow rate when specifying an injector, this accounts for injector deterioration and gives 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.

    M137 Performance Exhausts

    Only look to replace your exhaust if the existing exhaust is actually causing a restriction in flow.

    On most factory exhausts you should find that the exhaust flow rate is fine 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 can help increase the flow of gases through the engine.

    But if your exhaust is too large, ie: over 2.5 inches bore, you will lose a lot of your flow rate and end up lacking power and torque.

    Typically exhaust restrictions can be traced to the catalyst and filters installed, so adding a faster flowing race alternative such as a sports catalyst pretty much removes this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

    Weak spots, Issues & problem areas on the M137

    The M137 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 M137, 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 M137 engine please join us in our car forums where you can discuss M137 tuning options in more detail with our M137 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.

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    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 M137 tuning guides which get regular updates and revisions.

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