Mercedes M152 Tuning

"All you need to know about tuning and performance parts on the Mercedes M152 engine!"

Herein we review M152 tuning and report on the ultimate upgrades. Mercedes M152 are popular tuning projects and with the optimum sports parts like remapping, turbo upgrades and camshafts you will really enhance your driving pleasure.

History, Power & Specs of the M152 Engine

M152

The M152 is a NASP variant of the M157 engine and but has been revised and upgraded by the magic AMG Fairys.

M152 DE55

310 kW 421 PS 416 hp at 6,800 rpm 540 Nm 398lbft at 4,500 rpm
2012–2015

M152 DE55

2012–2015 R172 SLK55 AMG

Tuning the Mercedes M152 and best M152 performance parts.

Best M152 tuning parts

When talking about the best modifications for your M152 engine, we are going to focus on the parts that give the biggest return for your cash.

Significant gains on the M152 can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

Fast road camshafts normally boost the bhp and torque across the rev range, you may sacrifice a little bottom end power but your higher rpm power will improve.

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

On a daily driver should ideally to match your bhp range to your preferences.

I'd be surprised if you have ever thought or claimed that a M152 Motorsport cam is a pleasure to live with when driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

Each engine responds better to more or less aggressive camshaft durations check your engine on a rolling road.

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

Longer valve 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.

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Best Engine Mods for your car

  1. Mapping - remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.
  6. Typical stage 1 mods often include:
    Fast road camshaft, Sports exhaust header/manifold, Panel air filters, Intake manifolds, drilled & smoothed airbox, Remaps/piggy back ECU.

    Typical stage 2 mods often include:
    fuel pump upgrades, high flow fuel injectors, Ported and polished head, induction kit, Fast road cam, Sports catalyst & performance exhaust.

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

    Carefully think through your options and then source your modifications and set yourself a power target to void expensive mistakes.

    Mapping will help unlock the full potential of all the parts you've done to your M152.

    (In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

    It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but your results may rely on the parts you've carried out and the condition of your engine.

    Shoving more air and fuel into the M152 engine is the whole point to any performance tuning task.

    The intake manifolds take the air during the suck phase from the filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

    The shape and flow characteristics of the Air Intake manifolds can make a large improvement to fuel delivery on the M152.

    Commonly we find the intake manifolds are needing performance upgrades, although some OEM provide reasonably good intake manifolds.

    Big valve conversions on the M152, doing some M152 port enlargement and head flowing will also boost torque, this will give you a better torque increase on other upgrades.

    M152 Turbo upgrades

    NA (naturally aspirated) 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 M152

    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.

    When the engine is turbo charged modifications are more reliable and you'll see that turbo charged engines already contain strengthened components.

    There are tuning limits for every engine, with some being very over engineered and some just sufficiently able to handle stock powerIt is important to find these limits and fit stronger pistons, crank and engine components to utilize the power.

    We see many mechanics spending a loads of money on turbocharger upgrades on the M152 only to see the whole thing literally blow up when it's finished.

    Big capacity turbochargers often experience low end lag, and smaller turbochargers spool up quickly but do not have the high rpm engines power gains.

    Thanks to progress the range of turbo chargers is always evolving and we are seeing variable vane turbo chargers, where the vane profile is altered according to speed to lower lag and increase top end power.

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

    It is common that there is a restriction in the air flow sensor MAF/MAP on the M152 when a lot more air is being drawn into the engine.

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

    Adding a supercharger or additional turbo will make large torque gains, although more difficult to setup. We have this guide to twinchargers if you want to read more.

    Fuelling

    You will need to ensure that the engine is not starved of fuel so will have to ramp up the fuelling when you start extending past 20% of a torque increase.Don't forget to over specify your flow rate on the injectors.

    The accepted safe increase is to add another 20% when buying an injector, this accounts for injector deterioration and provides a little 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.

    M152 Performance Exhausts

    You may need to upgrade your exhaust if the current exhaust is actually causing a restriction.

    On most factory exhausts you should find that the flow rate is ok 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 equal out the flow of gases through the engine.

    But if the exhaust is too large, ie: over 2.5 inches bore, you will lose a great deal of the flow rate and end up losing power and torque.

    Common exhaust restrictions come around the catalyst installed, so adding a freer flowing race alternative such as a sports catalyst pretty much removes this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

    Weak spots, Issues & problem areas on the M152

    The M152 engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

    Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

    Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

    Regular oil changes are vital on the M152, especially when tuned and will help extend the life and reliability of the engine.

    If you would like to know more, or just get some friendly advice on Tuning your M152 engine please join us in our car forums where you can discuss M152 tuning options in more detail with our M152 owners. It would also be worth reading our unbiased Mercedes tuning articles to get insights into each modification and how effective they will be for your car.

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    We love to hear what our visitors have got up to and which tuning parts work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these M152 tuning guides which get regular updates and revisions.

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