Modding upgrading and tuning the Mercedes OM642 engine!

Modifying and improving: "OM642 Modifications"

OM642 Modifications Guide

How to modify and upgrade the Mercedes OM642

"Comprehensive guide to tuning the Mercedes OM642 engine!"

Forums like the one at TorqueCars often are getting posts about how to improve the OM642 from people inquiring about getting more power from the OM642 and wanting to know what are the things tuners recommend when it comes to OM642 modifications. So let us look into Mercedes OM642 modifications and outline the best mods that work on this great engine and point out some problems along the way.

The Mercedes OM642 make awesome project engines and with the ultimate modified upgrades like ECU maps, turbo improvements and camshafts you will noticeably improve your driving experience.

In this article we look into OM642 tuning and outline the best modifications.

When talking about the top parts for your OM642 engine, we are going to focus on the mods that give the best power gain for you spend.

OM642 induction kits

Improving air intake on the OM642

You need air matched to fuel for an engine to work. If there is too little fuel then it will run lean, if there is insufficient air it runs rich resulting in lost power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Pulling fuel and air into the OM642 engine is the primary aim to any engine upgrade project.

It is not unusual that there's a restriction in the air flow sensor (AFM/MAF/MAP) on the OM642 when loads more air is being drawn into the engine.

When tuning you may well find you need to get an air sensor or flow meter capable of upto 4 bars to cope with quite large power gains, whereas the OEM air sensor was restricting performance at a much lower level.

Headers take the air from the filter and allow it to be fed into the engine cylinders.

Design and rate of flow of the Intake headers can make a noticeable effect on to fuel atomisation on the OM642.

Commonly we find the air intake manifolds are crying out for motorsport parts, although a few OEM provide reasonably good air intake manifolds.

Larger OM642 valves, doing a bit of port matching and head flowing will also raise bhp and torque, and importantly will permit an improved bhp and torque increase on other upgrades.

OM642 performance cam tips.

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

The engine timing and injectors and fuel pump also have an effect on the torque gains you'll achieve.

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.

Altering your OM642 cam will make a dramatic difference to the engine torque. Choosing a higher performance cam profile raises the torque accordingly.

NB: Fast road cams tend to increase the power across the rpm range, you may sacrifice a little low end bhp but your top end will improve.

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

A Motorsport and race cam is not great in heavy traffic.

You should ideally match your torque band to your usage of the car so for a daily driver stick with a fast road OM642 cam

Stage 1, 2 and 3 mods for the OM642

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 OM642 parts:

Fast road camshaft, Intake headers, Remaps/piggy back ECU, Panel air filters, Drilled & smoothed airbox, Sports exhaust manifold.

Stage 2 OM642 parts:

high flow fuel injectors, Ported and polished head, fuel pump upgrades, Sports catalyst & performance exhaust, Fast road cam, induction kit.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Stage 3 OM642 parts:

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

The OM642 engines make great tuning projects and thankfully there are plenty of upgrades and performance parts out there.

ECU flashing will help fully realize the full potential of all the upgrades you've done to your OM642.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved usually depend much on the upgrades you've applied and the condition of your engine.

Turbo modifications on the OM642

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the 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 impressive power gains.

When your car is turbo charged upgrades are going to make more power and we find turbocharged engines use more solid components.

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

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

We've seen guys spending a fortune on turbocharger upgrades on the OM642 only to suffer the indignity of watching the engine catastrophically fail soon after it's first rolling road session.

Large upgraded turbochargers will usually suffer no power at low rpm, and smaller turbochargers spool up quickly but don't have the peak end bhp gains.

We are pleased that the selection of turbo units is always evolving and we now see variable vane turbo units, permitting the vane profile is altered according to speed to lower lag and increase top end torque.

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

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large performance gains, although more challenging to get working. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the OM642

You will need to ensure that the engine is not starved of fuel so will have to pay attention to the fuelling when you start exceeding 20% of a torque hike. Care modifiers usually say to be generous with your injectors flow rate.

As a rule of thumb add another 20% when buying an injector, this allows for injector deterioration and gives a little spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended OM642 performance exhaust upgrades

Only look to replace your exhaust system with an upgraded one is if the current exhaust is creating a flow problem.

On most factory exhausts you should find that the exhaust flow rate is good even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts increase the flow of air through the engine.

But if your exhaust is too big, ie: it's over two and a half inches diameter, you will lose much of your flow rate and end up sapping power and torque.

Usual exhaust restrictions can be traced to the catalyst and filters installed, so adding a faster flowing performance alternative will help avoid this restriction.

Decatting (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the OM642

Like most engines an OM642, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the OM642, failure to do this will exacerbate engine wear, on a tuned OM642 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your OM642 why not pop over to the forums at TorqueCars where you can chat about OM642 tuning options and read about others projects who may be planning to do similar modifications on their OM642.

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