Tuning the Mercedes OM608

"Comprehensive guide to performance parts and tuning the Mercedes OM608 engine!"

We often are getting posts inquiring about getting more power from the OM608 and wanting to know what are the optimum OM608 power upgrades. So let us look into Mercedes OM608 mods and outline the best mods that work on this great engine and point out some common pitfalls along the way.

Here we look at OM608 tuning and report on the optimum upgrades. Mercedes OM608 are popular engines and with the best modified mods like remaps, turbo kits and camshafts you will really improve your driving pleasure.

When talking about the top parts for your OM608 engine, we are going to concentrate on the tuning parts that give the best value for money.

Altering your OM608 cam will make a dramatic difference to the engine power band. Choosing a higher performance cam profile raises the power band accordingly.

NB: Fast road cams commonly bump the performance across the rpm range, you could sacrifice a little bottom end bhp but high end rpm power will be better.

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

A Race cam will just annoy you whilst in heavy traffic.

You should ideally match your power band to your typical driving style so for a typical daily driver stick with a shorter duration OM608 cam

Different OM608 engines respond better to more aggressive cam durations than others.

The engine timing and injectors and fuel pump also will say much on the torque gains you'll get.

Longer 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.

OM608 Tuning Stages

Stage 1 OM608 modifications: Fast road camshaft, Intake headers, Panel air filters, Drilled & smoothed airbox, Remaps/piggy back ECU, Sports exhaust manifold.

Stage 2 OM608 modifications: fuel pump upgrades, Sports catalyst & performance exhaust, Ported and polished head, Fast road cam, high flow fuel injectors, induction kit.

Stage 3 OM608 modifications: Twin charging conversions, Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Competition cam, Crank and Piston upgrades to alter compression.

ECU flashing helps to establish the full potential of all the parts you've done to your OM608.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the end result usually differs on the parts you've carried out and the condition of your engine.

Pushing air into each cylinder is the main goal to any engine upgrade job.

Intake manifold take the air during the suck phase from the intake filter and allow it to be drawn into the engine and mixed with fuel.

The bore size, shape and flow characteristics of the Plenum can make a noticeable effect on to fuel mixing and power on the OM608.

It's not uncommon that plenum chambers are improved through a performance upgrade, although a few makers provide reasonably well designed plenum chambers.

Increasing the OM608 valve size, getting OM608 port enlargement and head flowing will also improve performance, and more importantly will make space for a greater performance increase on other parts.

Turbo upgrades for the OM608

NASP 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 OM608

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

When the engine is fitted with a turbo parts are simpler to install and most turbocharged engines are built with more solid components.

There are weak spots for every engine, with some being extremely strong and some only able to handle stock power

It is important to find these restrictions and fit better quality crank and pistons to handle the power.

There are many car owners spending a lots of money on turbo upgrades on the OM608 only to see the whole thing literally blow up on it's first outing after it's been finished.

Large turbochargers will usually experience a bottom end lag, and low capacity turbochargers spool up more quickly but don't have the peak rpm torque gains.

We are pleased that the range of turbochargers is always moving on and we now see variable vane turbochargers, where the vane angle is altered according to speed to lower lag and increase top end torque.

Twin scroll turbochargers divert the exhaust flow into a couple of channels and flow these at differently designed vanes in the turbo. They also increase the scavenging effect of the engine.

You'll commonly see there's a limitation in the air flow sensor AFM/MAP on the OM608 when considerably more air is being drawn into the engine.

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

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

Uprating OM608 fuel injectors

Don't omit to increase the fuelling when you are increasing the bhp and torque - it makes the car more thirsty. It makes sense to be generous with your injector capacity.

As a rule of thumb add 20% when buying an injector, this takes into account injector deterioration and allows you some 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.

Best OM608 performance exhausts

You may need to increase your exhaust if your exhaust is creating a restriction in flow.

On most factory exhausts you'll see your flow rate is still 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 increase the flow of gases through the engine.

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

Usual exhaust restrictions typically happen through the catalyst and or DPF filters which manufacturers fit, especially as they start to get worn and carbon builds up, so adding a faster flowing performance alternative will help avoid this restriction.

Problems and issues to look out for on the OM608

The OM608 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the OM608, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your OM608 engine please join us in our friendly forum where you can discuss tuning options in more detail with our OM608 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We really like hearing from our readers, and hearing about which mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our OM608 guides and tips are kept up to date.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Mercedes. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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