Modding uprating the Mercedes M266 engine!

The Lowdown on "M266 Modifications"

How to modify and upgrade the Mercedes M266

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

Sites like TorqueCars are frequently getting messages about how to improve the M266 from people inquiring about getting more power from the M266 and wanting to know what are the ultimate M266 modifications. So let us look into Mercedes M266 upgrades and outline the best modifications on this great engine and point out some common pitfalls along the way.

Now we will outline options for your M266 tuning and report on the optimum upgrades. Mercedes M266 are good project engines and with the optimum tuning modifications like a remap, turbo improvements and camshafts you will noticeably increase your driving pleasure.

Just because particular tuning mods are popular with M266 owners it doesn't mean it is good, we will focus on the best tuning mods that will give your M266 the best power gain for you spend.

Without us subscribing to the common myth of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

M266 induction kits

Improving air intake on the M266

You need air and fuel for an engine to work. If there is little supply of fuel then it will run lean, if there is insufficient air it runs rich resulting in lost power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Pushing fuel and air into your M266 is the aim to any engine performance tuning project.

You'll commonly see there is a limitation in the air flow sensor MAF/MAP 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 was restricting bhp and torque at a much lower level.

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

Shape and flow rate of the Headers can make a substantial difference to to fuel atomisation on the M266.

Most intake manifold are crying out for an upgrade, although some manufacturers provide fairly well optimized intake manifold.

Increasing the M266 valve size, carrying out port work and head flowing will also raise bhp and torque, and more importantly will raise potential for a greater bhp and torque increase on other modifications.

M266 performance cam tips.

Some M266 engines respond better to more or less aggressive camshaft durations so set your engine up on a rolling road.

The ECU mapping and fuel pump and injectors also will make differences on the torque gains you'll make.

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.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen camshaft profile, so large torque gains are on offer for camshaft upgrades.

NB: Fast road camshafts commonly push up the torque over the rpm band, you might lose a little low end bhp but the higher rpm power will improve.

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

A Motorsport and race camshaft won't do well if in heavy traffic.

You should ideally optimize your engines power to your usage of the car so for a typical daily driver stick with a shorter duration M266 camshaft

Stage 1, 2 and 3 mods for the M266

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 M266 parts:

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

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Stage 2 M266 parts:

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

Stage 3 M266 parts:

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

Plan your options and then source your tuning parts and set yourself a power target to avoid disappointment.

ECU flashing allows a tuner to unlock the full potential of all the tuning mods you've done to your M266.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved usually differs on the tuning mods you've carried out and the condition of your engine.

Turbo modifications on the M266

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the 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 major power gains.

When your car is fitted with a turbo modifications are going to net you a larger power gain and most turbo charged engines are made using stronger components.

There are reliable limits for every engine, with some being extremely strong and some only just able to handle stock power

See where you'll find these limitations and fit better quality components to handle the power.

It's not unheard of guys spending a loads of money on turbo upgrades on the M266 only to see the motor go up in smoke soon after it's first rolling road session.

Larger capacity turbo units tend to experience low end lag, and low capacity turbo units spool up quickly but do not have the peak rpm bhp gains.

Over the last 20 years the market of turbo chargers is always increasing and we commonly find variable vane turbo chargers, permitting the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbo chargers divert the exhaust flow into two channels and push these at differently designed vanes in the turbocharger. They also increase the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although more difficult to get working. We have this article on twincharging if you want to read more.

Tips about fuel supply on the M266

You will need to ensure that the engine is not starved of fuel so will have to uprate the fuelling when you start going beyond 20% of a power hike. It is important to over specify your flow rate on the injectors.

The rule of thumb is to add 15% capacity when buying an injector, helps cope with injector deterioration and affords a little spare capacity should the engine require more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended M266 performance exhaust upgrades

Only look to improve your exhaust system with an upgraded one is if the current exhaust is actually creating a restriction.

On most factory exhausts you should find that your flow rate is fine even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts can help equal out the flow of air through the engine.

But if the exhaust pipe is too large, ie: it's over two and a half inches diameter, you will lose a lot of your flow rate and end up sapping power and torque.

The usual suspects causing problems in your exhaust flow rate are traced to the emissions filters installed, so adding a faster flowing sports alternative will help avoid this restriction.

Decats (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the M266

Like most engines an M266, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the M266, failure to do this will exacerbate engine wear, on a tuned M266 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your M266 why not pop over to the forums at TorqueCars where you can chat about M266 tuning options and read about others projects who may be planning to do similar modifications on their M266.

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