Modding upgrading and tuning the Mercedes M159 engine!

Tuners tips on "M159 Modifications"

M159 Modifications Guide

How to modify and upgrade the Mercedes M159

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

TorqueCars are frequently getting emails requesting information on how to improve the M159 from people inquiring about getting more power from the M159 and wanting to know what are the best M159 modifications. So let us look into Mercedes M159 tuning mods and outline the best modifications on this great engine and point out some common pitfalls along the way.

In this article we provide a guide to M159 tuning and summarise the optimum mods that work. Mercedes M159 are awesome to work on and with the right uprated upgrades like a remap, turbo kits and camshafts you will increase your driving enjoyment.

Just because particular upgrades are are common on M159 it doesn't mean its worth having, so we'll concentrate on the optimum upgrades that will give your M159 the biggest power gain return for your cash.

Without us subscribing to the popular mentality 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'.

M159 induction kits

Improving air intake on the M159

You need air and fuel for an engine to work. If there is insufficient fuel then it will run lean, if there is a lack of air it runs rich sapping power and potentially damaging the engine. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the goal to any engine performance tuning task to pull air into your M159 but this has a knock on effect with the air flow sensor.

You'll commonly see there's a limitation in the air flow sensor MAP/MAF/AFM on the M159 when loads more air is being sucked 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 sapped bhp and torque at a much lower level.

Air Intake manifolds transmit the during the engines suck phase from the air cleaner and allow it to be pulled into the engine and mixed with fuel.

The bore size, shape and rate of flow of the Plenum can make a noticeable difference to to fuel mixing and power on the M159.

We often see intake manifold are crying out for an upgrade, although some car makers provide decently flowing intake manifold.

Increasing the M159 valve size, doing some port work and head flowing will also lift bhp, & importantly will afford you raising the bhp increase on other tuning mods.

M159 performance cam tips.

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

The engine timing and injectors and fuel pump also have a large bearing on the torque gains you'll get.

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.

Significant air intake, and exhaust improvements on the M159 can be made from camshaft upgrades. Changing the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

NB: Fast road camshafts usually boost the bhp through the rev band, you might lose a little low end bhp but the high end rpm power will be higher.

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

On a car used daily you must carefully try to match your torque band to your driving style.

I'd be gobsmaked if you have found a M159 Race camshaft is a pleasure to live with when driving around busy urban areas.

Stage 1, 2 and 3 mods for the M159

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 M159 parts:

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

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

Stage 2 M159 parts:

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

Stage 3 M159 parts:

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

Carefully think through your options and then find your tuning parts and set yourself a power target to avoid wasting your time and money.

Remaps will help to establish the full potential of all the parts you've done to your M159.

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 results will depend much on the parts you've carried out and the condition of your engine.

Turbo modifications on the M159

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 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 impressive power gains.

If an engine is fitted with a turbocharger parts are giving better power gains and you'll see that turbocharged engines use uprated components.

However most engines will need better parts at higher power limits

See where you'll find these restrictions and install stronger pistons, crank and engine components to handle the power.

We see many drivers spending a a stack of money on turbo charger upgrades on the M159 only to experience the motor literally blow up when it's used in anger.

Big turbo chargers tend to experience a bottom end lag, and small turbo chargers spool up more quickly but don't have the peak end engines power gains.

Over the last 20 years the world of turbos is always moving on and we now see variable vane turbos, where the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbos divert the exhaust flow into two channels and flow these at differently designed vanes in the turbocharger. They also boost the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large torque gains, although more complex to configure. We have this article on twincharging if you want to read more.

Tips about fuel supply on the M159

Don't omit to increase the fuel delivery when you are increasing the power - it makes the car more thirsty. We strongly recommend you to over specify your injectors flow rate.

As a rule of thumb add 15% when fitting an injector, this allows for injector deterioration and affords a bit of spare capacity should the engine require 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 M159 performance exhaust upgrades

You may need to upgrade your exhaust system with an upgraded one is if your current exhaust is actually creating a restriction.

On most factory exhausts you should find that the exhaust flow rate is fine 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 usually air flow through the engine but avoid an exhaust that is too large or you may end up will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

Typically exhaust restrictions are traced to the catalysts installed, so adding a better flowing performance alternative will help avoid this restriction.

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

Faults issues and things to look out for on the M159

Like most engines an M159, 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 M159, failure to do this will exacerbate engine wear, on a tuned M159 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 M159 why not pop over to the forums at TorqueCars where you can chat about M159 tuning options and read about others projects who may be planning to do similar modifications on their M159.

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