Mercedes M166 Tuning

"All you need to know about tuning the Mercedes M166 engine!"

The Mercedes M166 are popular tuning projects and with a few sensible motorsport tuning mods like a remap, turbo kits and camshafts you will substantially enhance your driving enjoyment.

We shall examine M166 tuning and show the greatest modifications.

History, Power & Specs of the Engine

M166 E14

1997–2004 W168 A140 60 kW (82 PS; 80 hp) (96 lbft)

M166 E16

60 kW (82 PS; 80 hp) (103 lbft)

2001–2005 W639 Vito 1.6
1997–2004 W168 A160

M166 E19 92 kW

(125 PS; 123 hp) (133 lbft)

1999–2004 W168 A190
2001–2005 W639 Vito 1.9
2001-2005 W414 Vaneo 1.9

M166 E21 103 kW

(140 PS; 138 hp) 205 Nm (151 lbft)

2002–2004 W168 A210

Tuning the Mercedes M166 and best M166 performance parts.

Best M166 parts

The greatest M166 tuning mods on an engine are as we have found the ones that give the biggest return for your cash.

We won't be swayed by popular M166 tuning mods, they need to be cost effective.

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

Fast road cams normally bump the bhp and torque over the rev range, you might lose a little low end bhp but the top end will improve.

Race cams, bump the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a typical daily driver should ideally to optimize your torque band to your typical driving style.

You'll never have ever thought or claimed that a M166 Race 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.

Some M166 engines respond better to extreme cam durations check your engine on a rolling road.

The ecu map and fuel pump and injectors also have a large bearing on the power gains you'll get.

Longer 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. 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.

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

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

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

 

The M166 power plant make great tuning projects and we note that there is an increase of parts and tuning parts out there.

 

ECU flashing will help unlock the full potential of all the mods you've done to your M166.

(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 usually vary depending on the mods you've done and the condition of your engine.

It is vital to any tuning task to get fuel and air into the M166 engine

The intake plenum carry the air during the suck phase from the filter and allow it to be sucked into the engine and mixed with fuel.

The shape and flow rate of the Plenum can make a substantial improvement to fuel engine efficiency on the M166.

It's not uncommon that intake manifold are crying out for a performance upgrade, although some makers provide decently flowing intake manifold.

Fitting big valve kits, doing some M166 port enlargement and head flowing will also raise power, and significantly will raise potential for increasing the power 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 M166

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.

If your motor is turbo charged tuning parts are simpler to install and we find turbo engines are made using harder and stronger components.

However most engines have weakspots

It is important to find these restrictions and fit stronger pistons, crank and engine components to handle the power.

It's not unheard of car owners spending a lots of money on turbo charger upgrades on the M166 only to suffer the indignity of watching the engine go up in smoke just after it's used in anger.

Big capacity turbos commonly suffer no power at low rpm, and smaller turbos spool up much more quickly but do not have the peak end power band gains.

In recent times the selection of turbo units is always developing and we commonly find variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbo units divert the exhaust flow into a couple of channels and push these at differently profiled vanes in the turbo. They also boost the scavenging effect of the engine.

It is not unusual that there's a limitation in the air flow sensor AFM/MAP on the M166 when considerably more air is being sucked into the engine.

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

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

Fuelling

You will need to ensure that the engine is not starved of fuel so need to pay attention to the fuelling when you start going beyond 20% of a torque increase.It is important to be generous with your injector capacity.

 

The rule of thumb is to add 20% capacity when specifying an injector, this allows for injector deterioration and allows you some 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.

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

You may need to increase your exhaust if the current exhaust is actually creating a flow problem.

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

 

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

Common exhaust restrictions can be traced to the filters installed, so adding a faster flowing performance catalyst removes the restriction. We note that performance cats perform similarly to decats and have the added benefit of keeping your car street legal, as decats or catalyst removal is illegal in most territories for road going cars.

Weak spots, Issues & problem areas on the M166

The M166 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 M166, 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 M166 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M166 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 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 M166 tuning guides which get regular updates and revisions.

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