Mercedes OM642 Tuning

"All you need to know about performance tuning the Mercedes OM642 engine!"

A site visitor emailed and posted questions for more information on the OM642 and how to tune it up and modify it, so we've created this article to take you through what we feel are the main modifications that we rate and are the greatest upgrades you can do to this engine.

Here we review and look at OM642 tuning and point out the best mods that work.

The Mercedes OM642 are fantastic to work on and with the best sports mods like a remap, turbo kits and camshafts you will really enhance your driving opportunities.

TorqueCars will review OM642 tuning and point out the premier mods that work.

History, Power & Specs of the OM642 Engine


European models:

195 kW (265 PS; 261 hp) 620 Nm (457 lbft)

US vehicles:

  • 157 kW (213 PS; 211 hp) 540 Nm (398 lbft)

As fitted to the...

  • Mercedes/Dodge Sprinter: 440 Nm (325 lbft).
  • Mercedes/Dodge Sprinter: 140 kW (190 PS; 188 hp).
  • Dodge / Freightliner Trucks / Mercedes-Benz Sprinter (2006–Present)
  • Jeep Grand Cherokee WK/WH (2005-2010 (Europe)1, 2007-2008 (North America)
  • Jeep Commander XK/XH (2006-2010 (Europe))
  • Mercedes-Benz C320 CDI (2005–2009)
  • Mercedes-Benz E280 & E320 CDI/Bluetec (2007-2009) models 211.02 & 022
  • Mercedes-Benz C320 CDI et C350 CDI (2009–2014)
  • Mercedes-Benz CLK320 CDI (2005-2010)
  • Mercedes-Benz E350 CDI/Bluetec (2010–2016) Models 212.024
  • Mercedes-Benz G350 CDI/Bluetec (2007–2018)
  • Mercedes-Benz GLK 350 CD (2013–2015)
  • Mercedes-Benz R320/350 CDI/Bluetec (2007–2012) Models 251.122 & 125
  • Mercedes-Benz ML320/350 CDI/Bluetec (2007–2019) Models 164.122, 125 & 024
  • Mercedes-Benz GL320/350 CDI/Bluetec (2006–2012) Models 164.822, 825, & 824
  • Mercedes-Benz GLC 350 d (2016-2019)
  • Mercedes-Benz S320/350 CDI/Bluetec (2005–2013) Models 221.183
  • Mercedes-Benz CLS320/350 CDI/Bluetec (2005–2018) Models 219.322; 218.326, 926, 394, 994, 323, 923, 393, 993
  • Chrysler 300C (2006-2011) (Europe and Australia only)
  • Mercedes-Benz Vito Van 120 cdi and Vito 204 Sports (2006–2013 UK)

Tuning the Mercedes OM642 and best OM642 performance parts.

Best OM642 upgrades

The best OM642 upgrades on an engine are obviously the ones that give the biggest return for your cash.

We won't be swayed by popular OM642 upgrades, they need to be cost effective. The clear stand out winner would be a remap, pushing power to around 300hp, the engines can cope with figures approaching 400hp, but you should really start looking at internal engine mods at that level.

OM642 Camshaft upgrades

First the theory behind camshaft upgrades, and then we'll see how effective they are on the OM642.

The camshaft profile plays a big part in the engine's power output so camshaft upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen camshaft profile, so large bhp gains are on offer for camshaft upgrades.

Diesels are in the main, and as is the case with the OM642, a low RPM engine, where they deliver a nice fat wide torque band, so they are not particularly suited to cam upgrades but there are gains to be had, particularly if you have tuned/remapped and sorted the air intake and exhaust.

You should ideally optimize your bhp range to your driving style so for a daily driver stick with a shorter duration OM642 cam

Some OM642 engines respond better to more or less aggressive camshaft durations so view each engine as unique.

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.

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

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

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

The OM642 engines make great tuning projects and we're pleased to see that there are quite a few choices of parts and performance parts out there.

OM642 remaps

The ECU mapping and fuelling also have a large bearing on the bhp gains you'll hit. ECU mapping will help unlock the full potential of all the mods you've done to your OM642.

It will usually give you upto30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but the outcome usually relies on the mods you've fitted and the condition of your engine.

A tune/remap through the OBDII port is typically done in around 15minutes, giving a massive power hike. But there are some decent piggy back ECU devices around which take over the ECU and up the power and these are a simple DIY install.

Be careful because there are some very cheap rip off units out that just force more fuel into the engine and it will create a host of problems further down the line.

OM642 air intakes

Pulling more air and fuel into your OM642 is the main goal to any engine performance tuning project.

The intake plenum take the air from the filter and allow it to be sucked into the engine and mixed with fuel.

The shape and rate of flow of the Plenum can make a large improvement to fuel engine efficiency on the OM642. For most applications the headers and intake design is not too bad, but a few where space was limited leave much to be desired.

Most manifolds are crying out for motorsport parts, although a few OEM provide fairly well optimized headers.

Big valve conversions on the OM642, doing some port work and head flowing will also boost torque, the fantastic side effect is it will permit increasing the torque increase on other modifications.

OM642 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 OM642

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

If the engine has a turbo already fitted tuning parts are going to make more power and you will discover turbocharged engines already contain more solid components. The higher powered OM642 variants are typically fitted with better parts than the lower powered ones.

There are practical limits for every engine, with some being extremely strong and some only just able to handle stock power. See where you'll find these restrictions and upgrade to better quality crank and pistons to utilize the power.

Turbo upgrades depend very much on your power target a 300 hp project will require something like the HTD2262, with its 45/62mm compressor wheel and 50/46mm turbine wheel.

Going beyond this the HTD2872 or HTD3073BB make more sense with the latter boasting ball bearings which help it spool up faster and maintain its reliability. These offer a 50/72mm or 54/73mm compressor wheel and turbines come it at 51/49mm and 58/54mm respectively.

The latter makes more power but will suffer from a little more low end lag, so bear this in mind.

We've seen people spending a lot of money on turbo charger upgrades on the OM642 only to suffer the humiliation of seeing the engine block catastrophically fail soon after it's completed.

Big upgraded turbochargers will usually experience low end lag, and little turbochargers spool up more quickly but won't have the peak rpm power band gains.

In the last 10 years the market of turbo chargers is always moving on and we now see variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end power.

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

It is common that there is a restriction in the air flow sensor AFM/MAP on the OM642 when considerably more air is being drawn into the engine.

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

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

OM642 Fuelling

When you lift the bhp you will need to increase to the fuel delivery.

More bhp needs more fuel and the best way to address this on the OM642 is to increase the fuel rail pressure and fit a better fuel pump and injectors.

We strongly recommend you to over specify your flow rate on the injectors.

The accepted safe increase is to add another 20% when fitting an injector, this allows for injector deterioration and affords 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.

OM642 Performance Exhausts

Only look to upgrade your exhaust if the existing exhaust is actually causing a restriction.

On most factory exhausts you'll see the 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.

Sports exhausts can help equal out the flow of gases through the engine.

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

Typically exhaust restrictions are traced to the catalysts installed, so adding a better flowing sports alternative is the answer. This keeps the car road legal and will flow much better due to its 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 OM642

The OM642 engines are generally reliable and solid units, as long as you follow the manufacturer's 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 the design of this engine, 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 OM642, 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 OM642 engine please join us in our car forums where you can discuss OM642 tuning options in more detail with our OM642 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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One Response to “OM642 Tuning”

  1. Leif christensen says:

    Thankyou for the informative article
    I have been searching for some headers without luck
    Are there any on the market ?

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