Find out about "M156 Modifications"

How to modify and upgrade the Mercedes M156

"Comprehensive guide to performance tuning the Mercedes M156 engine!"

Sites like TorqueCars are frequently seeing threads about how to improve the M156 from people wanting to know what are the things tuners are recommending when it comes to M156 modifications. So let us look into Mercedes M156 parts and outline the best upgrades on this great engine and point out some common pitfalls along the way.

The Mercedes M156 offer good returns when tuned and with carefully chosen uprated parts like remapping, turbo improvements and camshafts you will positively enhance your driving experience.

This pages aim is outline options for your M156 tuning and report on the best mods that work.

Just because particular modifications are popular with M156 owners it doesn't mean you should fit it, we will concentrate on the best modifications that will give your M156 the best value for money to power increase.

Without us subscribing to the 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'.

Improving air intake on the M156

You need fuel and air for an engine to work. If there is little supply of fuel then it will run lean, if there is little flow of air it runs rich resulting in lost power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the whole point to any engine upgrade job to feed more air into the M156 engine but this has a knock on effect with the air flow sensor.

It is common that there's a limit in the air flow sensor MAF/MAP on the M156 when a lot more air is being sucked into the engine.

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

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

Structure and rate of flow of the Plenum can make a substantial change to fuel delivery on the M156.

On popular production engines headers are ripe for performance upgrades, although some manufacturers provide well optimised headers.

Increasing the M156 valve size, carrying out port work and head flowing will also boost torque, & more importantly will give you raising the torque increase on other parts.

M156 performance cam tips.

Different M156 engines respond better to less aggressive cam durations so set your engine up on a rolling road.

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

Extending exhaust or intake durations can alter the bhp 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.

Altering your M156 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 camshafts normally push up the bhp over the rpm band, you could drop a little low end power but the top end will be better.

Race camshafts, push up the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a typical daily driver you need to match your bhp range to your usage of the car.

I'd never find a M156 Competition cam is a pleasure to live with when in heavy traffic.

Stage 1, 2 and 3 mods for the M156

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 M156 parts:

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

Stage 2 M156 parts:

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

Stage 3 M156 parts:

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

A remap should help to release the full potential of all the parts you've done to your M156.

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 power output often vary depending on the parts you've carried out and the condition of your engine.

Turbo modifications on the M156

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 M156.

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

If a car is turbo charged tuning mods are relatively easy and you will discover turbo engines are made using uprated components.

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

Discover these limits and install better quality components to utilize the power.

It's not unheard of people spending a lot of money on turbo charger upgrades on the M156 only to suffer the humiliation of seeing the engine go up in smoke just after it's been enthusiastically driven.

Larger turbochargers commonly suffer a bottom end lag, and smaller turbochargers spool up really quickly but don't have the peak rpm torque gains.

Over the last 20 years the choice of turbo units is always moving on and we commonly find variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbo units divert the exhaust gases into a couple of channels and push these at differently profiled vanes in the turbocharger. They also improve the scavenging effect of the engine.

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

Tips about fuel supply on the M156

Don't overlook the need to pay attention to the fuel delivery when you are increasing the performance - it makes the car more thirsty. Most tuners we speak with say to be generous with your injectors flow rate.

As a rule of thumb add 15% to the flow rate when fitting an injector, this allows for injector deterioration and affords you some 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 M156 performance exhaust upgrades

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

On most factory exhausts you'll find the exhaust flow rate is still 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 out of the engine but do not go too wide or you may end up will reduce the flow rate. Stick to one and a half to two and half inches for best results.

The usual suspects causing problems in your exhaust flow rate come around the catalyst and filters installed, so adding a faster 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 M156

Like most engines an M156, 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 M156, failure to do this will exacerbate engine wear, on a tuned M156 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 M156 why not pop over to the forums at TorqueCars where you can chat about M156 tuning options and read about others projects who may be planning to do similar modifications on their M156.

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This entry was posted under Makes and Models. Tags: engine, mercedes
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