Modding and performance tuning parts for the Mercedes M112 engine!

Modifying and improving: "M112 Modifications"

M112 Modifications Guide

How to modify and upgrade the Mercedes M112

"Comprehensive guide to tuning and performance parts on the Mercedes M112 engine!"

Popular tuning sites like TorqueCars are regularly getting posts asking about how to improve the M112 from people wanting to know what are the things tuners are recommending when it comes to M112 mods that work. So let us look into Mercedes M112 upgrades and outline the best upgrades on this great engine and point out some common pitfalls along the way.

This pages aim is look at M112 tuning and highlight the ultimate modifications. Mercedes M112 are awesome to work on and with the best uprated mods like ECU maps, turbo improvements and camshafts you will substantially increase your driving experience.

When talking about the greatest parts for your M112 engine, we are going to focus on the upgrades that give the best power gain for you money.

M112 induction kits

Improving air intake on the M112

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

So Forcing air into each cylinder is vital to any engine upgrade task.

You'll commonly see there's a limit in the air flow sensor AFM/MAF on the M112 when a lot more air is being sucked into the engine.

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

Intake manifolds transmit the air during the suck phase from the air filter and allow it to be pulled into the engine cylinders.

The size of bore and shape and flow characteristics of the Plenum can make a noticeable difference to to fuel atomisation on the M112.

I usually find plenum chambers are crying out for an upgrade, although some OEM provide reasonably good plenum chambers.

Increasing the M112 valve size, doing some port matching and head flowing will also raise power, this will raise potential for a greater power increase on other upgrades.

M112 performance cam tips.

Different M112 engines respond better to different camshaft durations check your engine on a rolling road.

The ecu map and fuelling also have a large bearing on the torque gains you'll get.

Altering valve durations 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.

Significant air intake, and exhaust improvements on the M112 can be made from camshaft upgrades. Changing the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road cams tend to boost the bhp across the rev range, you might lose a little bottom end bhp but your higher rpm power will improve.

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

In a typical daily driver you need to match your torque band to your cars usage.

I'd be gobsmaked if you have ever thought a M112 Motorsport cam is a pleasure to live with when driving around busy urban areas.

Stage 1, 2 and 3 mods for the M112

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 M112 parts:

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

Stage 2 M112 parts:

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

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

Stage 3 M112 parts:

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

The M112 power trains are fantastic to work on and we see that there is an increase of upgrades and performance parts about.

Remapping allows a tuner to unlock the full potential of all the tuning mods you've done to your M112.

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 depend much on the tuning mods you've fitted and the condition of your engine.

Turbo modifications on the M112

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 M112.

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

If a car is turbocharged, upgrades are simpler to install and we find turbo charged engines are made with strengthened components.

However every engines will need better parts at higher power limits

It is important to find these restrictions and fit better quality crank and pistons to survive the power.

We see many guys spending a loads of money on turbo upgrades on the M112 only to experience the engine explode just after it's been enthusiastically driven.

Large turbo units commonly experience low end lag, and small turbo units spool up really quickly but won't have the peak end bhp gains.

Thankfully the choice of turbo chargers is always improving and we commonly find variable vane turbo chargers, where the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo chargers divert the exhaust flow into a couple of channels and feed these at differently designed vanes in the turbo. 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 performance gains, although more complex to setup. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the M112

Don't forget to improve the fuel delivery when you are increasing the bhp - it makes the car more thirsty. Care modifiers usually say to be generous with your injector capacity.

As a rule of thumb add 20% when fitting an injector, which takes into account injector deterioration and allows you some 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 M112 performance exhaust upgrades

You may need to increase your exhaust system with an upgraded one is if the existing exhaust is actually creating a flow problem.

On most factory exhausts you should find that your flow rate is ok 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 generally help improve air flow out of the engine but do not go too wide or you may end up will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

Usual exhaust restrictions are in the catalyst and filters installed, so adding a better flowing performance 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 M112

Like most engines an M112, 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 M112, failure to do this will exacerbate engine wear, on a tuned M112 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 M112 why not pop over to the forums at TorqueCars where you can chat about M112 tuning options and read about others projects who may be planning to do similar modifications on their M112.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We want to know your experiences with tuning parts on your M112, it helps us improve our tips and keeps us current so please use the comments box to drop a tip.

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Check out TorqueCars new YouTube channel, and see their awesome new content...


Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article