Mercedes M266 Tuning

"All you need to know about tuning and performance parts on the Mercedes M266 engine!"

Here we examine the options for your M266 tuning and outline the ultimate modifications. Mercedes M266 are popular tuning projects and with a few sensible tuning tuning mods like remaps, turbo kits and camshafts you will substantially maximize your driving fun.

History, Power & Specs of the Engine

This great engine was fitted to cars in the A-class and B-class range it was an 8 valve engine with a SOHC configuration.

• M266.920 1.5
• M266.940 1.7
• M266.960 2.0
• M266.980 2.0 Turbo

Tuning the Mercedes M266 and best M266 performance parts.

Best M266 mods

Just because particular upgrades are appear in lots of M266 projects it doesn't mean its worth having, instead we will be recommend only tuning mods that we have found to be effective upgrades ie: that will give your M266 the biggest power gain return for your cash.

Significant gains on the M266 can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

Fast road camshafts commonly bump the power across the rpm range, you could drop a little bottom end bhp but the higher rpm power will be better.

Competition camshafts, bump 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 won't do well if on the daily commute, because the lumpy idle will make the car prone to stall and smooth driving at low rpm becomes impossible. If you are developing a track car this doesn't matter as you are in the high end of your RPM range anyway and that is where you want the power to be.

You should ideally match your power band to your preferences so for a car used daily stick with a mild fast road M266 cam

Some M266 engines respond better to less aggressive cam durations than others.

The engine timing and fuelling also have an effect on the power gains you'll hit.

Altering valve 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.

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

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

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

A remap will help release the full potential of all the upgrades you've done to your M266.

(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 end result may differs on the upgrades you've done and the condition of your engine.

Forcing fuel and air into the M266 engine is the aim to any performance tuning job.

The intake plenum take the air during the suck phase from the air cleaner and allow it to be drawn into the engine and mixed with fuel.

Structure and flow rate of the Plenum can make a big change to fuel mixing and power on the M266.

I usually find manifolds are in dire need of a performance upgrade, although some OEM provide reasonably well designed headers.

Adding a M266 larger valve kit, doing a bit of M266 port enlargement and head flowing will also increase bhp, and more importantly will permit increasing the bhp increase on other tuning parts.

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 M266

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

If your motor is fitted with a turbo tuning mods are more reliable and we find turbo charged engines are built with strengthened components.

However engines have limits

It is important to find these limitations and fit forged components to cope with the power.

There are many car owners spending a loads of money on turbo charger upgrades on the M266 only to experience the car go up in smoke just after it's been completed.

Bigger turbo chargers often experience a bottom end lag, and smaller turbo chargers spool up really quickly but do not have the peak rpm engines power gains.

Thankfully the market of turbos is always moving on and we are seeing variable vane turbos, allowing the vane angle is altered according to speed to lower lag and increase top end performance.

Twin scroll turbos divert the exhaust gases into a couple of channels and direct these at differently profiled vanes in the turbo charger. They also help the scavenging effect of the engine.

It is common that there is a limit in the air flow sensor AFM/MAF on the M266 when loads 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 limited performance at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more challenging to get working. We have this article covering twinchargers if you want to read more.

Fuelling

When you increase the bhp you will need to uprate to the fuelling.

More bhp needs more fuel. We would recommend you to be generous with your flow rate on the injectors.

As a rule of thumb add 20% when buying an injector, this accounts for injector deterioration and provides 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
• 58 PSI 1022cc/min 600hp

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
• 58 PSI 937cc/min 600hp

Exhaust

Only look to upgrade your exhaust if your exhaust is actually causing a restriction.

On most factory exhausts you'll see the flow rate is good even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Do not go with the largest exhaust you can source this will slow the exhaust rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Common exhaust restrictions can be traced to the emissions filters installed, so adding a higher flowing sports alternative is the answer. This keeps the car road legal and will flow much better due to it's higher internal surface area and design, so has the added benefit of keeping your car road legal. The alternative decat should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars..

Weak spots, Issues & problem areas on the M266

The M266 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 M266, 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 M266 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M266 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which modifications 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 M266 tuning guides which get regular updates and revisions.

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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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