Mercedes OM604 Tuning

"All you need to know about tuning and performance parts on the Mercedes OM604 engine!"

The Mercedes OM604 really good project engines and with the optimum modified tuning mods like remapping, turbo kits and camshafts you will substantially improve your driving opportunities.

Our aim here is to examine the options for your OM604 tuning and point out the best modifications.

History, Power & Specs of the OM604 Engine

OM 604.910 EVE

70 kW (95 PS; 94 hp) @ 5000 rpm 150 Nm (111 lbft) @ 3100 rpm

OM 604.910 EVE

55 kW (75 PS; 74 hp) @ 5000 rpm 151 Nm (111 lbft) @ 3100 rpm

OM 604.912 EVE

70 kW (95 PS; 94 hp) @ 5000 rpm 152 Nm (111 lbft) @ 3100 rpm

OM 604.912 EVE

55 kW (75 PS; 74 hp) @ 5000 rpm 153 Nm (111 lbft) @ 3100 rpm

OM 604.915 EVE

65 kW (88 PS; 87 hp) @ 5000 rpm 135 Nm (100 lbft) @ 2000 rpm

OM 604.917 EVE

65 kW (88 PS; 87 hp) @ 5000 rpm 135 Nm (100 lbft) @ 2000 rpm

  • 1998 W202 C-Class, 1998 W210 E-Class
  • 1998 W202 C-Class, 1998 W210 E-Class
  • 2000 W90x Sprinter
  • 2000 W90x Sprinter
  • 1999 W210 E-Class, 2000 W203 C-Class
  • 2003 W203 C-Class
  • 2000 W90x Sprinter
  • 1999 W210 E-Class for Belgium
  • 1999 W210 E-Class, 2000 W203 C-Class

Tuning the Mercedes OM604 and best OM604 performance parts.

Best OM604 parts

When talking about the ultimate modifications for your OM604 engine, we are going to concentrate on the ones that give the best power gain for you money.

Significant gains on the OM604 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

Fast road cams tend to bump the bhp over the rpm range, you may sacrifice a little low down power but your top end will be higher.

Motorsport and race cams, bump the top end 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 in heavy traffic.

You should ideally match your torque band to your usage of the car so for a road car stick with a shorter duration OM604 camshaft

Some OM604 engines respond better to extreme cam durations than others.

The engine timing and injectors and fuel pump also will make differences on the torque gains you'll hit.

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

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

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

    Review your options and then find your modifications and set yourself a power target to avoid wasting your time and money.

    A remap will help to establish the full potential of all the tuning parts you've done to your OM604.

    (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 often vary depending on the tuning parts you've fitted and the condition of your engine.

    It is the whole point to any engine performance tuning task to feed more air into the OM604 engine

    The intake manifolds flow rates are important because this channels the air from the filter and allow it to be sucked into the engine cylinders.

    The size of bore and shape and rate of flow of the Air Intake manifolds can make a substantial improvement to fuel mixing and power on the OM604.

    Most intake are ripe for aftermarket tuning parts, although some car makers provide fairly well optimized intake.

    Adding a OM604 larger valve kit, getting 3 or 5 angle valve jobs and porting and head flowing will also increase performance, & more importantly will permit increasing the performance increase on other parts.

    OM604 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 OM604

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

    When the engine is turbocharged, parts are more reliable and you will discover turbo engines already contain more solid components.

    However you'll find engines have weakspots.It is important to find these limits and upgrade to more solid crank and pistons to handle the power.

    It's not unheard of mechanics spending a lot of money on turbo upgrades on the OM604 only to see the whole thing go up in smoke soon after it's used on the roads.

    Larger upgraded turbochargers often experience low end lag, and small turbochargers spool up really quickly but don't have the high rpm engines power gains.

    We are pleased that the choice of turbo chargers is always improving and we commonly find variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end torque.

    Twin scroll turbo chargers divert the exhaust gases into 2 channels and feed these at differently angled vanes in the turbocharger. They also boost the scavenging effect of the engine.

    You'll commonly see there is a limitation in the air flow sensor AFM/MAP on the OM604 when considerably more air is being sucked into the engine.

    You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited power at a much lower level.

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


    You will need to ensure that the engine is not starved of fuel so will have to look at the fuelling when you start exceeding 20% of a performance increase.It makes sense to be generous with your injector capacity.

    The accepted safe increase is to add 20% to the flow rate when fitting an injector, this accounts for injector deterioration and gives a bit of 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.

    OM604 Performance Exhausts

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

    On most factory exhausts you'll find the flow rate is 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 equal out the flow of gases through the engine.

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

    Usual exhaust restrictions are in the emissions filters installed, so adding a freer 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 OM604

    The OM604 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 OM604, 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 OM604 engine please join us in our car forums where you can discuss OM604 tuning options in more detail with our OM604 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 tuning mods 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 OM604 tuning guides which get regular updates and revisions.

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