Mercedes M133 Tuning

"All you need to know about tuning the Mercedes M133 engine!"

Now we will examine M133 tuning and highlight the premier modifications.

It already boasts strong crank and pistons and a twin scroll turbo giving you a fantastic base to work from with your tuning mods.

Mercedes M133 are popular engines and with the best sports modifications like ECU maps, turbo improvements and camshafts you will positively maximize your driving opportunities.

History, Power & Specs of the Engine

Winning engine of the year 3 times, is no mean feat and shows the effort that AMG have put into development of this engine.

Innovations include direct injection, low friction cylinder wall coatings and a cleverly designed cooling system.

M133 DE20 LA

  • (360 PS; 355 hp) at 6,000 rpm 450Nm (332lbft) at 2,250–5,000 rpm
  • (381 PS; 375 hp) at 6,000 rpm 475Nm (350lbft) at 2,250–5,000 rpm

M133 DE20 LA 355 hp

  • 2013–2015 C117 CLA45 AMG
  • 2013–2015 W176 A45 AMG
  • 2014–2015 X156 GLA45 AMG

M133 DE20 LA 375 hp)

  • 2015–2018 C117 CLA45 AMG
  • 2015–2018 W176 A45 AMG
  • 2015–2019 X156 GLA45 AMG

Tuning the Mercedes M133 and best M133 performance parts.

Best M133 tuning parts

When talking about the best modifications for your M133 engine, we are going to focus on the upgrades that give the best power gain for you spend.

Significant gains on the M133 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

Fast road camshafts tend to push up the bhp over the rev range, you could sacrifice a little low down power but the top end will improve.

Motorsport 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 car driven daily must carefully try to optimize your engines power to your cars usage.

You will never have found a M133 Competition cam is a pleasure to live with when driving in heavy traffic. The low end idle will be very lumpy and irregular, so something you would notice on a track when you drive in the upper third of the rpm band, but on roads this is a serious issue and we've heard from lots of drivers lamenting their decision to add an extreme competition cam profile to their engine.

Different M133 engines respond better to less aggressive cam durations check your engine on a rolling road.

The engine timing and fuel pump and injectors also have an effect 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.

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Best Engine Mods for your car

  1. Engine Tunes - engine tuning/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.

Typical stage 1 mods often include:
Fast road camshaft, drilled & smoothed airbox, Intake manifolds, Remaps/piggy back ECU, Panel air filters, Sports exhaust header/manifold.

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

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


Carefully think through your options and then find your parts and set yourself a power target to avoid disappointment.


Mapping helps to establish the full potential of all the modifications you've done to your M133.

(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 the outcome will differs on the modifications you've done and the condition of your engine.

It is the whole point to any engine upgrade task to pull more air into your M133

Intake carry the air from the air filter and allow it to be sucked into the engine cylinders with fuel for the squish phase.

The shape and flow characteristics of the Intake can make a large effect on to fuel delivery on the M133.

Many mass produced engine intake are in desperate need of aftermarket tuning parts, although some OEM provide decently flowing intake.

Adding a M133 larger valve kit, doing a bit of port work and head flowing will also increase performance, & more importantly will permit raising the performance increase on other upgrades.

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 M133

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.

If an engine has a turbo already fitted parts are more reliable and most turbo charged engines are made with harder and stronger components.

However engines have weakspots

Research these limits and upgrade to better pistons and crank to handle the power.

We've seen mechanics spending a loads on turbo charger upgrades on the M133 only to experience the engine literally blow up just after it's completed.

Larger turbochargers tend to suffer low end lag, and low capacity turbochargers spool up quickly but won't have the top end bhp gains.

In recent times the world of turbo chargers is always evolving and we now see variable vane turbo chargers, allowing the vane angle 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 push these at differently profiled vanes in the turbocharger. They also help the scavenging effect of the engine.

It is not unusual that there's a limit in the air flow sensor AFM/MAF on the M133 when considerably more air is being pulled into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting torque at a much lower level.

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


You will need to ensure that the engine is not starved of fuel so must uprate the fuelling when you start extending past 20% of a bhp and torque increase.Most tuners we speak with say to over specify your injectors flow rate.


The rule of thumb is to add 20% to the flow rate when specifying an injector, this allows for injector deterioration and affords 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.

All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

4 Cylinder turbocharged engines

  • 58 PSI 340cc/min 200hp
  • 58 PSI 511cc/min 300hp
  • 58 PSI 682cc/min 400hp

4 Cylinder NA (naturally aspirated) engines

  • 58 PSI 285cc/min 200hp
  • 58 PSI 426cc/min 300hp

4 Cylinder supercharged engines

  • 58 PSI 312cc/min 200hp
  • 58 PSI 468cc/min 300hp
  • 58 PSI 625cc/min 400hp


You only need to uprate your exhaust if the current exhaust is creating a restriction in flow.

On most factory exhausts you'll find the flow rate is 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 generally help improve air flow through the engine but do not go too large or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to 2.5 inches for best results.

Typically exhaust restrictions can be located 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 M133

The M133 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.

There was a recall affecting turbo oil feed line issues which caused excessive play in the turbo in quite a large number of cars.

Regular oil changes are vital on the M133, 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 M133 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M133 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 love to hear what our visitors have got up to and which tuning mods 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 M133 tuning guides which get regular updates and revisions.

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2 Responses to “M133 Tuning”

  1. Matimu Timothy says:

    Very helpful..where can i get the camshaft for the A45AMG

  2. TorqueCars says:

    Near me in the UK I would go to Kent Cams or Piper cams, they offer regrinds on stock cams to any profile you need including a mild fast road one. Our stores link above will take you to our ebay directory and you should find a supplier on there.

    Bear in mind that AMG have already fitted a better profile cam to their versions.

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