Mercedes OM612 Tuning

"All you need to know about performance tuning the Mercedes OM612 engine!"

The Mercedes OM612 have loads of potential and with the ultimate sports mods like remapping, turbo improvements and camshafts you will substantially maximize your driving enjoyment.

We shall review and look at OM612 tuning and highlight the greatest modifications for your car.

History, Power & Specs of the OM612 Engine


  • 156 PS (115 kW; 154 hp) @ 3800 rpm 330 Nm (243 lbft) @ 1400–2400 rpm

2000 W90x Sprinter and W463 G 270 CDI

  • 163 PS (120 kW; 161 hp) @ 4200 rpm 370 Nm (273 lbft) @ 1600–2800 rpm

1999 W210 E-Class and 2000 W203 C-Class for Belgium

  • 170 PS (125 kW; 168 hp) @ 4200 rpm 370 Nm (273 lbft) @ 1600–2800 rpm

1999 W210 E-Class and 2000 W203 C-Class for others than Belgium

  • 231 PS (170 kW; 228 hp) @ 3800 rpm 540 Nm (398 lbft) @ 2000 rpm

2002-2004 Mercedes-Benz C30 CDI AMG

Tuning the Mercedes OM612 and best OM612 performance parts.

Best OM612 tuning parts

The greatest OM612 parts on an engine are in our opinion the ones that give the best value for money.

We won't be swayed by popular OM612 parts, they need to be cost effective.

Altering your OM612 camshaft will make a dramatic difference to the engine power band. Choosing a higher performance camshaft profile raises the power band accordingly.

Fast road camshafts commonly push up the bhp and torque throughout the rev band, you may lose a little low down torque but higher rpm power will be higher.

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

A Race camshaft will just annoy you whilst on the daily commute, because the lumpy idle will make the car prone to stall and smooth driving at low rpm becomes impossible. If you are developing a track car this doesn't matter as you are in the high end of your RPM range anyway and that is where you want the power to be.

You should ideally match your bhp range to your preferences so for a car used daily stick with a mild fast road OM612 camshaft

Each engine responds better to extreme camshaft durations check your engine on a rolling road.

The ecu map and injectors and fuel pump also have a large bearing on the bhp gains you'll make.

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

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

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

    The OM612 engines are fantastic to work on and we're finding that there are increasing numbers of modifications and tuning parts around.

    Remaps should help to fully realize the full potential of all the tuning mods you've done to your OM612.

    (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 depend much on the tuning mods you've fitted and the condition of your engine.

    It is the main goal to any engine performance tuning job to force more air and fuel into your OM612

    Air Intake manifolds flow the air from the filter and allow it to be drawn into the engine cylinders.

    Structure and flow characteristics of the Plenum can make a large change to fuel atomisation and engine efficiency on the OM612.

    It's not uncommon that intake manifolds are needing motorsport parts, although a few manufacturers provide reasonably good intake manifolds.

    Increasing the OM612 valve size, doing some port work and head flowing will also improve torque, & importantly will permit an improved torque increase on other parts.

    OM612 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 OM612

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

    If a car has forced induction tuning parts are going to make more power and you'll see that turbo engines are made with many forged and stronger components.

    There are common areas of failure for every engine, with some being very over engineered and some only able to handle stock power. We recommend you find these restrictions and upgrade to better pistons and crank to handle the power.

    Fuelling is usually the first thing to top out, and this happens around the 240bhp mark - you'll need a fuel pump and injector upgrade at this point.

    Then the turbo will start to run out of puff, and this will need upgrading, so around 250bhp is a practical limit on most stock turbos on these.

    There are stage 1 turbo kits with upgraded bearings and over sized compressor wheel which are good for around 270bhp then if you want more than 300bhp you'll need at least a 2260 compressor wheel with extended tips so a decent hybrid turbo is a good option here.

    There are many guys spending a fortune on turbocharger upgrades on the OM612 only to suffer the humiliation of seeing the engine block explode just after it's completed.

    Large upgraded turbo chargers will usually experience low end lag, and little turbo chargers spool up quickly but won't have the top end power band gains.

    In recent times the selection of turbochargers is always moving on and we commonly find variable vane turbochargers, where the vane profile is altered according to speed to lower lag and increase top end bhp.

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

    It is common that there's a restriction in the air flow sensor AFM/MAP on the OM612 when a lot 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 limited bhp and torque at a much lower level.

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


    When you improve the power you will need to uprate to the fuel delivery.

    More power needs more fuel. We strongly recommend you to be generous with your injector capacity.

    As a rule of thumb add another 20% when specifying an injector, this allows for injector deterioration and affords 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.

    OM612 Performance Exhausts

    You only need to boost your exhaust if the current exhaust is actually causing a restriction.

    On most factory exhausts you should find that the flow rate is still good even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

    Don't go with the largest exhaust you can source you'll reduce 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.

    Usual exhaust restrictions come around the filters installed, so adding a faster 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 OM612

    The OM612 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 OM612, 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 OM612 engine please join us in our car forums where you can discuss OM612 tuning options in more detail with our OM612 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 OM612 tuning guides which get regular updates and revisions.

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