Modding tuning and best performance upgrades on the Mercedes M111 engine!

Tuning guide "M111 Modifications"

M111 Modifications Guide

How to modify and upgrade the Mercedes M111

"Comprehensive guide to tuning and performance parts on the Mercedes M111 engine!"

Our friends at TorqueCars are frequently getting emails asking how to improve the M111 from people wanting to know what are the best M111 mods that work. So let us look into Mercedes M111 upgrades and outline the best upgrades on this great engine and point out some problems along the way.

The Mercedes M111 are awesome to work on and with a few sensible sports tuning mods like ECU maps, turbo upgrades and camshafts you will positively improve your driving fun.

Let us examine the options for your M111 tuning and point out the greatest mods that work.

When talking about the optimum parts for your M111 engine, we are going to concentrate on the parts that give the best value for money.

M111 induction kits

Improving air intake on the M111

You need air and fuel for an engine to work. If there is not enough fuel then it will run lean, if there is little flow of air it runs rich resulting in lost power which risks damage to the M111. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Feeding more air into each cylinder is the main goal to any engine tuning task.

It is not unusual that there's a limit in the air flow sensor AFM/MAF on the M111 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 power at a much lower level.

The intake plenum take the air from the intake filter and allow it to be fed into the engine cylinders with fuel for the squish phase.

Design and flow rate of the Headers can make a large improvement to fuel atomisation on the M111.

Many mass produced engine intake are improved through an upgrade, although some makers provide decently flowing intake.

Fitting big valve kits, doing a bit of M111 port enlargement and head flowing will also boost torque, and more importantly will give you increasing the torque increase on other parts.

M111 performance cam tips.

Different M111 engines even from the same production line will vary with some working better on different setups or needing less aggressive camshaft durations, but porting and flowing the head should reduce the differences and give consistent results.

The engine timing and fuelling also will make differences on the power gains you'll achieve.

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.

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

NB: Fast road cams normally increase the bhp throughout the rev range, you could sacrifice a little low end torque but your higher rpm power will be lifted.

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

A Race camshaft won't do well if driving around busy urban areas.

You should ideally optimize your power band to your typical driving style so for a road car stick with a fast road M111 camshaft

Stage 1, 2 and 3 mods for the M111

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 M111 parts:

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

Stage 2 M111 parts:

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

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

Stage 3 M111 parts:

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

Review your options and then buy your parts and set yourself a power target to avoid expensive mistakes.

Mapping helps unlock the full potential of all the tuning mods you've done to your M111.

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 your mileage usually vary depending on the tuning mods you've fitted and the condition of your engine.

Turbo modifications on the M111

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 M111.

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 has a turbocharger modifications are going to net you a larger power gain and we find turbocharged engines are made with strengthened components.

There are weak spots for every engine, with some being very over engineered and some only just able to handle stock power

We recommend you find these restrictions and fit stronger pistons, crank and engine components to utilize the power.

We see many people spending a loads of money on turbo upgrades on the M111 only to see the car go up in smoke just after it's finished.

Larger upgraded turbochargers will usually experience a bottom end lag, and smaller turbochargers spool up more quickly but don't have the top end power band gains.

In the last 10 years the choice of turbos is always evolving and we commonly find variable vane turbos, allowing the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

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

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large performance gains, although more challenging to configure. We have this article covering twinchargers if you want to read more.

Tips about fuel supply on the M111

You will need to ensure that the engine is not starved of fuel so need to uprate the fuelling when you start extending past 20% of a torque hike. Experienced tuners recommend to be generous with your injectors flow rate.

The rule of thumb is to add another 20% when fitting an injector, this allows for injector deterioration and allows some spare capacity should the engine need 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 M111 performance exhaust upgrades

Only look to increase your exhaust system with an upgraded one is if your exhaust is actually causing a flow problem.

On most factory exhausts you'll find 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.

Note that with the widest exhaust you can source you'll slow up the exhaust flow rate - the best for power gains are usually between one and a half to two and half inches. Your exhaust design, the bend angles and construction are what have more effect on flow rates than your pipe width to a certain extent. So the exhaust design is a big factor.

Typically exhaust restrictions come around the emissions filters installed, so adding a freer flowing performance alternative will help avoid this restriction.

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

Faults issues and things to look out for on the M111

Like most engines an M111, 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 M111, failure to do this will exacerbate engine wear, on a tuned M111 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 M111 why not pop over to the forums at TorqueCars where you can chat about M111 tuning options and read about others projects who may be planning to do similar modifications on their M111.

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