Mercedes M112 Tuning

"All you need to know about performance tuning the Mercedes M112 engine!"

Now we shall review and look at M112 tuning and outline the greatest modifications. Mercedes M112 provide a fun base for your project and with the best modified tuning mods like ECU maps, turbo upgrades and camshafts you will maximize your driving enjoyment.

History, Power & Specs of the Engine

M112 E24 2.4

168 bhp (125 kW; 170 PS) 5500-6000 rpm and 225 Nm (166 lbft) 3000 - 5500 rpm.

  • 1996-2000 C240
  • 1998-2000 CLK240
  • 1998-2000 E240

M112 E26 2.6

(170 PS; 168 bhp) ECE @5,500 rpm 240 Nm (177 lbft) @4,500 rpm

  • 2000–2005 C240
  • 2000–2007 E240 (177 PS; 174 bhp)
  • 2002–2005 CLK240

M112 E28 2.8

204 bhp (152 kW; 207 PS) @5,700 rpm and 270 Nm (199 lbft) 3,000-5,000 rpm.

  • 1998–2000 C280
  • 1998–2006 S280
  • 1998–2004 E280

M112 E32 3.2

215-224 bhp @5,700 rpm with 315 Nm (232 lbft) @3,000-4,800 rpm.

  • 1998–2005 E320
  • 1997-2006 G320
  • 1998–2005 S320
  • 1998–2005 CLK320
  • 1998–2003 ML320
  • 2000–2004 C320
  • 2000–2003 SLK320
  • 2010–2015 Viano 3.0/Vito 119 (W639)
    2004-2008 Chrysler Crossfire

M112 E 32 ML 3.2

Supercharged* Mercedes-AMG C32/SLK32 engine
*helical Twin-screw type supercharger  (354 PS; 349 bhp) @6,100 rpm with 450 Nm (332 lbft) @3,000-4,600 rpm.

  • 2001–2003 C32 AMG
  • 2001–2003 SLK32 AMG
  • 2005-2006 SRT-6

M112 E37 3.7

(235 to 245 PS; 232 to 241 bhp) ECE @5,750 rpm with 344 Nm (254 lbft) @3,000-4,500 rpm.


  • 2003–2005 ML350
  • 2003–2006 S350
  • 2003-2006 SL350
  • 2004-2008 V350

Tuning the Mercedes M112 and best M112 performance parts.

Best M112 tuning mods

When talking about the optimum modifications for your M112 engine, we are going to concentrate on the ones that give the best power gain for you spend.

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

Fast road cams usually bump the torque throughout the rpm band, you may lose a little low down torque but the higher rpm power will be lifted.

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

A Motorsport and race cam will just annoy you whilst driving in heavy traffic.

You should ideally optimize your power band to your preferences so for a car used daily stick with a fast road M112 cam

Each engine responds better to more or less aggressive cam durations so set your engine up on a rolling road.

The ECU mapping and injectors and fuel pump also will make differences on the power gains you'll hit.

A longer valve duration can alter the power 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.

Please watch our video which covers the 5 principles of tuning your car. Be sure to keep up with our latest YouTube content and subscribe.

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.

Typical stage 1 mods often include:
Remaps/piggy back ECU, Sports exhaust header/manifold, Fast road camshaft, drilled & smoothed airbox, Panel air filters, Intake manifolds.

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

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


Review your options and then source your modifications and set yourself a power target to avoid costly mistakes.


ECU flashing allows a tuner to establish the full potential of all the upgrades you've done to your M112.

(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 end result may rely on the upgrades you've carried out and the condition of your engine.

Pulling more air and fuel into each cylinder is the aim to any engine modification task.

Air Intake manifolds flow the air during the suck phase from the filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

Structure and flow rate of the Intake manifold can make a substantial difference to fuel atomisation and engine efficiency on the M112.

On popular production engines manifolds are in desperate need of aftermarket tuning parts, although some makers provide well optimised headers.

Big valve conversions on the M112, doing a bit of port matching and head flowing will also increase bhp and torque, & more importantly will make space for increasing the bhp and torque increase on other tuning parts.

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 M112

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 your car is turbocharged, parts are relatively easy and turbocharged engines are built using more solid components.

There are reliable limits for every engine, with some being over specified and some just sufficiently able to handle stock power

We recommend you find these limitations and install stronger pistons, crank and engine components to utilize the power.

There are many people spending a lots of money on turbocharger upgrades on the M112 only to have the whole thing go up in smoke soon after it's used in anger.

Large turbo units commonly suffer no power at low rpm, and little turbo units spool up really quickly but do not have the peak rpm engines power gains.

In recent times the choice of turbos is always improving and we now see variable vane turbos, permitting the vane angle is altered according to speed to lower lag and increase top end performance.

Twin scroll turbos divert the exhaust gases into a couple of channels and direct these at differently angled vanes in the turbocharger. They also increase the scavenging effect of the engine.

It is common that there's a limit in the air flow sensor AFM/MAF on the M112 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 limited bhp at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more complex to install. We have this in depth look at twinchargers if you want to read more.


You will need to ensure that the engine is not starved of fuel so need to pay attention to the fuelling when you start exceeding 20% of a bhp and torque increase.It makes sense to over specify your injectors flow rate.

The accepted safe increase is to add 20% when specifying an injector, this accounts for injector deterioration and gives you some spare capacity should the engine need 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.


You only need to replace your exhaust if the current exhaust is creating a restriction in flow.

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

Do not go with the widest exhaust you can find you'll slow up the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Common exhaust restrictions can be traced to the catalyst and filters installed, so adding a better flowing sports alternative is the answer. This keeps the car road legal and will flow much better due to it's higher internal surface area and design, so has the added benefit of keeping your car road legal. The alternative decat should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars..

Weak spots, Issues & problem areas on the M112

The M112 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.

One thing to keep an eye out for is the crank pulley rubber disintegrates on pre 2007 models.

Regular oil changes are vital on the M112, 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 M112 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M112 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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