Mercedes OM611 Tuning

"All you need to know about tuning the Mercedes OM611 engine!"

The Mercedes OM611 are good project engines and with the right modified parts like remapping, turbo kits and camshafts you will really increase your driving pleasure.

TorqueCars will examine the options for your OM611 tuning and summarise the optimum mods that work.

History, Power & Specs of the OM611 Engine

  • 102 PS (75 kW; 101 hp) @ 4200 rpm 235 Nm (173 lbft) @ 1500 rpm

1998 W202 C-Class, 1998 W210 E-Class

  • 125 PS (92 kW; 123 hp) @ 4200 rpm 300 Nm (220 lbft) @ 1800 rpm

1998 W202 C-Class, 1998 W210 E-Class

  • 82 PS (60 kW; 81 hp) @ 3800 rpm 200 Nm (150 lbft) @ 1400–2600 rpm

2000 W90x Sprinter

  • 109 PS (80 kW; 108 hp) @ 3800 rpm 270 Nm (200 lbft) @ 1400–2400 rpm

2000 W90x Sprinter

  • 116 PS (85 kW; 114 hp) @ 4200 rpm 250 Nm (180 lbft) @ 1400–2600 rpm

1999 W210 E-Class, 2000 W203 C-Class

  • 122 PS (90 k W; 120 hp) @ 3800 rpm 270 Nm (200 lbft) @ 1600–2400 rpm

2003 W203 C-Class

  • 129 PS (95 kW; 127 hp) @ 3800 rpm 300 Nm (220 lbft) @ 1600–2400 rpm

2000 W90x Sprinter

  • 136 PS (100 kW; 134 hp) @ 4200 rpm 315 Nm (232 lbft) @ 1800–2600 rpm

1999 W210 E-Class for Belgium

  • 143 PS (105 kW; 141 hp) @ 4200 rpm 315 Nm (232 lbft)@ 1800–2600 rpm

1999 W210 E-Class, 2000 W203 C-Class

Tuning the Mercedes OM611 and best OM611 performance parts.

Best OM611 parts

The best OM611 parts on an engine are typically the ones that give the biggest return for your cash.

We won't be swayed by popular OM611 parts, they need to be cost effective.

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

Fast road camshafts tend to increase the torque throughout the rpm band, you might lose a little low down power but your high end rpm power will improve.

Race camshafts, 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 in heavy traffic.

You should ideally match your power band to your typical driving style so for a car used daily stick with a shorter duration OM611 camshaft

Different OM611 engines respond better to less aggressive cam durations so set your engine up on a rolling road.

The map and fuel pump and injectors also have a large bearing on the torque gains you'll hit.

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

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

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

    The OM611 units are great to work on and we're finding that there is a lot of modifications and performance parts around.

    Remaps helps to establish the full potential of all the upgrades you've done to your OM611.

    (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 often depend much on the upgrades you've done and the condition of your engine.

    Forcing more fuel and air into each cylinder is vital to any car tuning task.

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

    The shape and flow rate of the Intake manifold can make a large improvement to fuel engine efficiency on the OM611.

    We often see intake are begging for aftermarket tuning parts, although some makers provide decently flowing intake.

    Adding a OM611 larger valve kit, getting OM611 port enlargement and head flowing will also raise performance, & more importantly will raise potential for a greater performance increase on other tuning parts.

    OM611 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 OM611

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

    When your car has a turbo already fitted parts are going to make more power and turbo engines will have harder and stronger components.

    However most engines will have power limits.It is important to find these restrictions and install better quality components to cope with the power.

    It's not unheard of car owners spending a lots of money on turbocharger upgrades on the OM611 only to watch the engine block catastrophically fail when it's used in anger.

    Bigger capacity turbochargers often suffer no power at low rpm, and small turbochargers spool up really quickly but don't have the top end torque gains.

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

    Twin scroll turbos divert the exhaust flow into 2 channels and push these at differently profiled vanes in the turbo. They also help the scavenging effect of the engine.

    You'll commonly see there is a limitation in the air flow sensor AFM/MAP on the OM611 when a lot 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 sapped bhp and torque at a much lower level.

    Adding a supercharger or additional turbo will make large performance gains, although more difficult to get working. We have this in depth look at twinchargers if you want to read more.


    When you boost the bhp and torque you will need to ramp up to the fuelling.

    More bhp and torque needs more fuel. Don't forget to over specify your injector capacity.

    The rule of thumb is to add another 20% when fitting an injector, which takes into account injector deterioration and provides a bit of 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.

    OM611 Performance Exhausts

    You should look to boost your exhaust if your current exhaust is creating a flow problem.

    On most factory exhausts you'll find the 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 can help balance the flow of gases through the engine.

    But if your exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose much of the exhaust flow rate and end up sapping power and torque.

    Typically exhaust restrictions are traced to the catalysts installed, so adding a faster 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 OM611

    The OM611 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 OM611, 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 OM611 engine please join us in our car forums where you can discuss OM611 tuning options in more detail with our OM611 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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