Modding uprating the Mercedes M157 engine!

Discover "M157 Modifications"

How to modify and upgrade the Mercedes M157

"Comprehensive guide to tuning the Mercedes M157 engine!"

Our friends at TorqueCars are regularly seeing threads asking about how to improve the M157 from people inquiring about getting more power from the M157 and wanting to know what are the premier M157 upgrades. So let us look into Mercedes M157 modifications and outline the best modifications on this great engine and point out some problems along the way.

We shall review and look at M157 tuning and point out the premier modifications for your car. Mercedes M157 make a good tuning project and with carefully picked tuning upgrades like remapping, turbo upgrades and camshafts you will improve your driving opportunities.

Just because particular tuning mods are popular with M157 owners it doesn't mean you should fit it, we will concentrate on the top tuning mods that will give your M157 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'.

M157 induction kits

Improving air intake on the M157

You need air and 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 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 it's important to any engine tuning project to pull air into each cylinder but this has a knock on effect with the air flow sensor.

You'll commonly see there is a restriction in the air flow sensor MAP/MAF/AFM on the M157 when a lot more air is being pulled into the engine.

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

Intake headers flow the air from the filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

The shape and flow rate of the Intake headers can make a substantial improvement to fuel atomisation and engine efficiency on the M157.

Most air intake manifolds are ripe for aftermarket parts, although a few OEM provide well optimised air intake manifolds.

Fitting big valve kits, carrying out M157 port enlargement and head flowing will also increase torque, and more importantly will afford you raising the torque increase on other tuning parts.

M157 performance cam tips.

Each engine responds better to extreme cam durations so set your engine up on a rolling road.

The ecu map and fuel pump and injectors also have an effect on the power gains you'll get.

Extending exhaust or intake durations 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.

Significant air intake, and exhaust improvements on the M157 can be made from cam upgrades. Changing the cam profile alters the intake and exhaust durations on the engine and can dramatically change the engines power and power output.

NB: Fast road camshafts normally increase the bhp and torque throughout the rpm range, you might lose a little bottom end torque but higher rpm power will be better.

Competition camshafts, increase the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a car driven daily you should ideally to optimize your bhp range to your typical driving style.

You'll never have ever thought a M157 Race camshaft is a pleasure to live with when driving in heavy traffic.

Stage 1, 2 and 3 mods for the M157

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 M157 parts:

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

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

Stage 2 M157 parts:

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

Stage 3 M157 parts:

Engine balancing & blueprinting, Competition cam, 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.

The M157 engine blocks are fantastic to work on and thanks to their popularity there are increasing numbers of modifications and tuning parts around.

Remapping will help fully realize the full potential of all the modifications you've done to your M157.

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 differs on the modifications you've applied and the condition of your engine.

Turbo modifications on the M157

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 M157.

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 the engine has a turbo already fitted mods are relatively easy and most turbocharged engines are built with harder and stronger components.

There are practical limits for every engine, with some being extremely strong and some just sufficiently able to handle stock power

It is important to find these limits and install stronger pistons, crank and engine components to utilize the power.

It's not unheard of people spending a lot of money on turbocharger upgrades on the M157 only to suffer the humiliation of seeing the car catastrophically fail on it's first outing after it's been finished.

Larger capacity turbos will usually suffer low end lag, and low capacity turbos spool up much more quickly but won't have the high rpm bhp gains.

In recent times the choice of turbo chargers is always evolving and we now see variable vane turbo chargers, where the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbo chargers divert the exhaust flow into 2 channels and feed these at differently angled vanes in the turbo charger. They also increase 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 complex to setup. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the M157

When you raise the power you will need to look at to the fuel system.

More power needs more fuel. Most tuners we speak with say to be generous with your flow rate on the injectors.

As a rule of thumb add 15% when buying an injector, which takes into account injector deterioration and affords you some 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 M157 performance exhaust upgrades

The only time you should look to boost your exhaust system with an upgraded one is if your exhaust is creating a restriction in flow.

On most factory exhausts you'll see the flow rate is still ok 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.

Note that with the widest exhaust you can source you'll slow the exhaust rate - the best exhausts for power gains are usually between one and a half to two and half inches. Your exhaust design, the bend angles and construction are what have more effect on flow rates than your pipe width to a certain extent. So the exhaust design is a big factor.

Usual exhaust restrictions are in the filters installed, so adding a higher flowing race 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 M157

Like most engines an M157, 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 M157, failure to do this will exacerbate engine wear, on a tuned M157 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 M157 why not pop over to the forums at TorqueCars where you can chat about M157 tuning options and read about others projects who may be planning to do similar modifications on their M157.

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