Modding tuning and best performance upgrades on the Mercedes OM612 engine!

Tuners tips on "OM612 Modifications"

How to modify and upgrade the Mercedes OM612

"Comprehensive guide to tuning the Mercedes OM612 engine!"

Our friends at TorqueCars are always getting messages asking how to improve the OM612 from people inquiring about getting more power from the OM612 and wanting to know what are the best tips for OM612 upgrades. So let us look into Mercedes OM612 modifications and outline the best upgrades on this great engine and point out some common pitfalls along the way.

The Mercedes OM612 offer good returns when tuned and with the best tuning modifications like remaps, turbo upgrades and camshafts you will dramatically enhance your driving pleasure.

Let us consider OM612 tuning and summarise the best modifications for your car.

Just because particular tuning mods are popular with OM612 owners it doesn't mean you should fit it, so we'll focus on the optimum tuning mods that will give your OM612 the best value for money to power increase.

Without us subscribing to the common myth of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

OM612 induction kits

Improving air intake on the OM612

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 sapping power which risks damage to the OM612. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the fundamental goal to any engine upgrade job to feed more air and fuel into your OM612 but this has a knock on effect with the air flow sensor.

It is not unusual that there's a limitation in the air flow sensor (AFM/MAF/MAP) on the OM612 when loads more air is being sucked into the engine.

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited power at a much lower level.

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

Shape and flow rate of the Air Intake manifolds can make a big difference to to fuel engine efficiency on the OM612.

On popular production engines intake manifold are in dire need of aftermarket tuning parts, although some makers provide reasonably well designed intake manifold.

Increasing the OM612 valve size, carrying out OM612 port enlargement and head flowing will also improve performance, and more importantly will allow you to get a better performance increase on other tuning mods.

OM612 performance cam tips.

Different OM612 engines respond better to less aggressive camshaft durations so view each engine as unique.

The ECU mapping and injectors and fuel pump also will make differences on the power gains you'll get.

A longer valve duration can alter the power 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.

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

NB: Fast road cams commonly raise the performance through the rpm range, you may sacrifice a little low end bhp but high end rpm power will improve.

Race cams, raise the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Competition cam won't do well if in heavy traffic.

You should ideally match your power band to your usage of the car so for a road car stick with a fast road OM612 cam

Stage 1, 2 and 3 mods for the OM612

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 OM612 parts:

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

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

Stage 2 OM612 parts:

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

Stage 3 OM612 parts:

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

The OM612 power plant respond well to mods and we note that there is an increase of parts and tuning parts out there.

Mapping should help to release the full potential of all the tuning mods you've done to your OM612.

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 your mileage often depend much on the tuning mods you've done and the condition of your engine.

Turbo modifications on the OM612

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 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 major power gains.

When an engine is fitted with a turbo upgrades are simpler to install and turbocharged engines use more solid components.

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

Research these restrictions and upgrade to stronger pistons, crank and engine components to utilize the power.

There are many tuners spending a lots of money on turbo upgrades on the OM612 only to suffer the humiliation of seeing the whole thing throw a rod soon after it's been enthusiastically driven.

Larger upgraded turbo units tend to suffer no power at low rpm, and low capacity turbo units spool up much more quickly but don't have the peak end power band gains.

Thankfully the range of turbo chargers is always moving on and we are seeing variable vane turbo chargers, permitting the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbo chargers divert the exhaust flow into two channels and feed these at differently designed vanes in the turbo. 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 power gains, although more difficult to setup. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the OM612

Don't dismiss the need ramp up the fuel system when you are increasing the power - it makes the car more thirsty. Most tuners we speak with say to be generous with your injector capacity.

As a rule of thumb add another 20% when specifying an injector, this accounts 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 OM612 performance exhaust upgrades

You may need to upgrade your exhaust system with an upgraded one is if your exhaust is actually causing a restriction in flow.

On most factory exhausts you should find that the flow rate is still 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 can help increase the flow of air through the engine.

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

Typically exhaust restrictions can be traced to the emissions filters installed, so adding a higher flowing race alternative will help avoid this restriction.

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

Faults issues and things to look out for on the OM612

Like most engines an OM612, 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 OM612, failure to do this will exacerbate engine wear, on a tuned OM612 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 OM612 why not pop over to the forums at TorqueCars where you can chat about OM612 tuning options and read about others projects who may be planning to do similar modifications on their OM612.

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