Tuning the Mercedes M156

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

We often are getting messages inquiring about getting more power from the M156 and wanting to know what are the best M156 mods that work. So let us look into Mercedes M156 mods and outline the best mods that work on this great engine and point out some potential pitfalls along the way.

This pages aim is review and look at M156 tuning and report on the ultimate modifications for your car. Mercedes M156 really good project engines and with carefully chosen sports parts like a remap, turbo upgrades and camshafts you will really improve your driving opportunities.

When talking about the best parts for your M156 engine, we are going to concentrate on the mods that give the biggest return for your cash.

Altering your M156 camshaft will make a dramatic difference to the engine power band. Choosing a higher performance camshaft profile raises the power band accordingly.

NB: Fast road cams tend to boost the power over the rpm range, you may sacrifice a little low down power but your higher rpm power will be better.

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

A Motorsport cam makes it harder when driving around busy urban areas.

You should ideally optimize your power band to your driving style so for a typical daily driver stick with a mild fast road M156 cam

Some M156 engines respond better to more or less aggressive cam durations check your engine on a rolling road.

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

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.

M156 Tuning Stages

Stage 1 M156 modifications: Sports exhaust manifold, Remaps/piggy back ECU, Intake headers, Panel air filters, Drilled & smoothed airbox, Fast road camshaft.

Stage 2 M156 modifications: Fast road cam, Ported and polished head, induction kit, high flow fuel injectors, Sports catalyst & performance exhaust, fuel pump upgrades.

Stage 3 M156 modifications: Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Competition cam, Crank and Piston upgrades to alter compression, Engine balancing & blueprinting, Internal engine upgrades (head flowing porting/bigger valves).

ECU flashing should help to unlock the full potential of all the tuning parts you've done to your M156.

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

Feeding fuel and air into your M156 is the whole point to any tuning project.

Intake headers flow the air during the suck phase from the filter and allow it to be drawn into the engine cylinders.

The size of bore and shape and flow rate of the Intake can make a substantial change to fuel atomisation and engine efficiency on the M156.

On popular production engines intake manifold are in desperate need of performance upgrades, although some manufacturers provide decently flowing intake manifold.

Fitting big valve kits, doing some port matching and head flowing will also lift bhp and torque, and importantly will permit an improved bhp and torque increase on other upgrades.

Turbo upgrades for the M156

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 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 impressive power gains.

If the engine has a turbocharger parts are giving better power gains and we find turbo charged engines use harder and stronger components.

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

Discover these limitations and fit better quality crank and pistons to handle the power.

There are many people spending a lot of money on turbocharger upgrades on the M156 only to suffer the humiliation of seeing the motor explode when it's been finished.

Big upgraded turbochargers will usually experience no power at low rpm, and low capacity turbochargers spool up really quickly but do not have the peak end engines power gains.

Thanks to progress the selection of turbos is always improving and we commonly find variable vane turbos, where the vane profile is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbos divert the exhaust flow into a couple of channels and push these at differently angled vanes in the turbocharger. They also help the scavenging effect of the engine.

You'll commonly see there's a limitation in the air flow sensor (AFM/MAF/MAP) on the M156 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 was restricting performance at a much lower level.

Adding a supercharger or additional turbo will make large performance gains, although harder to get working. We have this feature on twinchargers if you want to read more.

Uprating M156 fuel injectors

Don't omit to raise the fuelling when you are increasing the torque - it makes the car more thirsty. It makes sense to be generous with your flow rate on the injectors.

As a rule of thumb add 20% capacity when specifying an injector, which takes into account injector deterioration and allows you some 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 M156 performance exhausts

You should look to replace your exhaust if your current exhaust is actually causing a restriction in flow.

On most factory exhausts you should find that your flow rate is still fine 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 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 1.5 to 2.5 inches for best results.

Common exhaust restrictions can be located the catalyst installed, so adding a freer flowing race alternative will help avoid this restriction.

Problems and issues to look out for on the M156

The M156 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M156, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M156 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M156 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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We really like hearing from our readers, and hearing about which tuning parts were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our M156 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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