Tuning the Mercedes M266

"Comprehensive guide to performance parts and tuning the Mercedes M266 engine!"

We are regularly seeing threads asking about the greatest M266 mods that work. So let us look into Mercedes M266 upgrades and outline the best upgrades on this great engine and point out some problems along the way.

In this article we outline options for your M266 tuning and provide tips on the best upgrades. Mercedes M266 really good project engines and with carefully chosen performance upgrades like remaps, turbo improvements and camshafts you will positively maximize your driving opportunities.

The optimum M266 parts on an engine are typically the ones that give the biggest return for your cash.

We won't be swayed by popular M266 parts, they need to be cost effective.

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 torque and power output.

NB: Fast road cams normally increase the performance through the rpm range, you may sacrifice a little low end bhp but the higher rpm power will be better.

Competition cams, increase 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 must carefully try to match your power band to your typical driving style.

I'd never find a M266 Motorsport cam is a pleasure to live with when in heavy traffic.

Different M266 engines respond better to less aggressive camshaft durations check your engine on a rolling road.

The ECU mapping and fuelling also will make differences on the power gains you'll get.

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.

M266 Tuning Stages

Stage 1 M266 modifications: Remaps/piggy back ECU, Fast road camshaft, Drilled & smoothed airbox, Intake headers, Panel air filters, Sports exhaust manifold.

Stage 2 M266 modifications: Ported and polished head, fuel pump upgrades, Sports catalyst & performance exhaust, induction kit, Fast road cam, high flow fuel injectors.

Stage 3 M266 modifications: Internal engine upgrades (head flowing porting/bigger valves), Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Competition cam, Engine balancing & blueprinting.

Remaps will help to establish the full potential of all the parts you've done to your M266.

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

It is the main goal to any performance tuning project to get air and fuel into your M266

Intake headers flow the air during the suck phase from the filter and allow it to be pulled into the engine and mixed with fuel.

Design and flow characteristics of the Intake can make a noticeable improvement to fuel atomisation and engine efficiency on the M266.

On popular production engines intake are in dire need of aftermarket parts, although a few manufacturers provide decently flowing intake.

Adding a M266 larger valve kit, doing a bit of port matching and head flowing will also boost bhp and torque, & importantly will raise potential for increasing the bhp and torque increase on other tuning mods.

Turbo upgrades for the M266

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 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.

When an engine has forced induction parts are more reliable and we find turbocharged engines already contain strengthened components.

There are tuning limits for every engine, with some being over specified and some only just able to handle stock power

Research these limits and fit better quality components to cope with the power.

There are many mechanics spending a a stack of money on turbo upgrades on the M266 only to suffer the indignity of watching the car literally blow up just after it's used on the roads.

Big turbo units tend to experience low end lag, and small turbo units spool up really quickly but don't have the high rpm engines power gains.

In the last 10 years the selection of turbos is always developing and we now see variable vane turbos, where the vane angle is altered according to speed to lower lag and increase top end torque.

Twin scroll turbos divert the exhaust flow into two channels and feed these at differently angled vanes in the turbo charger. They also help the scavenging effect of the engine.

You'll commonly see there is a restriction in the air flow sensor (AFM/MAF/MAP) on the M266 when loads 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 limited power at a much lower level.

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

Uprating M266 fuel injectors

When you lift the torque you will need to pay attention to to the fuelling.

More torque needs more fuel. Don't forget to over specify your injector capacity.

The accepted safe increase is to add 20% capacity when fitting an injector, this allows for injector deterioration and allows a little spare capacity should the engine need 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 M266 performance exhausts

You may need to replace your exhaust if your exhaust is creating a restriction.

On most factory exhausts you'll see 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 increase the flow of gases through the engine.

But if the exhaust is too big, ie: over 2.5 inches bore, you will lose a lot of your flow rate and end up lacking power and torque.

Common exhaust restrictions are traced to the catalyst installed, so adding a better flowing high performance alternative will help avoid this restriction.

Problems and issues to look out for on the M266

The M266 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M266, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information 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.

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We really like hearing from our readers, and hearing about which tuning mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our M266 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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