Tuning the Mercedes M159

"Comprehensive guide to performance tuning the Mercedes M159 engine!"

We are frequently getting posts about the optimum M159 mods that work. So let us look into Mercedes M159 parts and outline the best modifications on this great engine and point out some common pitfalls along the way.

The Mercedes M159 make a good tuning project and with carefully picked motorsport mods like a remap, turbo improvements and camshafts you will definitely enhance your driving pleasure.

TorqueCars will outline options for your M159 tuning and outline the optimum upgrades.

The ultimate M159 mods on an engine are usually the ones that give the biggest return for your cash.

We won't be swayed by popular M159 mods, they need to be cost effective.

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

NB: Fast road cams normally boost the performance over the rev band, you might lose a little low end power but the high end rpm power will improve.

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

A Motorsport and race camshaft will just annoy you whilst driving around busy urban areas.

You should ideally match your power band to your preferences so for a car driven daily stick with a shorter duration M159 camshaft

Some M159 engines respond better to different camshaft durations so set your engine up on a rolling road.

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

Extending exhaust or intake 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.

M159 Tuning Stages

Stage 1 M159 modifications: Fast road camshaft, Drilled & smoothed airbox, Remaps/piggy back ECU, Panel air filters, Sports exhaust manifold, Intake headers.

Stage 2 M159 modifications: induction kit, Ported and polished head, Fast road cam, fuel pump upgrades, high flow fuel injectors, Sports catalyst & performance exhaust.

Stage 3 M159 modifications: Internal engine upgrades (head flowing porting/bigger valves), Competition cam, Twin charging conversions, Engine balancing & blueprinting, Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger).

ECU flashing should help to release the full potential of all the tuning mods you've done to your M159.

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 rely on the tuning mods you've applied and the condition of your engine.

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

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

Design and rate of flow of the Intake can make a big improvement to fuel delivery on the M159.

Many mass produced engine plenum chambers are ripe for aftermarket parts, although some manufacturers provide reasonably good plenum chambers.

Big valve conversions on the M159, carrying out 3 or 5 angle valve jobs and porting and head flowing will also raise performance, & importantly will raise potential for increasing the performance increase on other upgrades.

Turbo upgrades for the M159

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 M159

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.

If your motor is fitted with a turbo modifications are relatively easy and most turbo engines already contain stronger components.

There are practical limits for every engine, with some being incredibly solid and some only just able to handle stock power

We recommend you find these restrictions and fit better quality crank and pistons to handle the power.

There are many car owners spending a loads on turbocharger upgrades on the M159 only to have the motor catastrophically fail soon after it's been finished.

Bigger turbo units will usually experience low end lag, and low capacity turbo units spool up much more quickly but do not have the high rpm power band gains.

Over the last 20 years the world of turbo chargers is always developing and we commonly find variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbo chargers divert the exhaust flow into two channels and feed these at differently angled vanes in the turbo charger. They also improve the scavenging effect of the engine.

You'll commonly see there's a limit in the air flow sensor AFM/MAP on the M159 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 performance at a much lower level.

Adding a supercharger or additional turbo will make large bhp gains, although more complex to setup. We have this article on twincharging if you want to read more.

Uprating M159 fuel injectors

You will need to ensure that the engine is not starved of fuel so should pay attention to the fuelling when you start exceeding 20% of a torque increase.We strongly recommend you to over specify your injectors flow rate.

The accepted safe increase is to add 20% when specifying an injector, helps cope with injector deterioration and provides 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.

Best M159 performance exhausts

You should look to boost your exhaust if your exhaust is actually creating a restriction in flow.

On most factory exhausts you should find that 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.

Note that with the widest exhaust you can find this will reduce the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Typically exhaust restrictions can be located the catalysts installed, so adding a higher flowing race alternative will help avoid this restriction.

Problems and issues to look out for on the M159

The M159 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M159, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M159 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M159 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 upgrades were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our M159 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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