Modding uprating the Mercedes M102 engine!

The Lowdown on "M102 Modifications"

How to modify and upgrade the Mercedes M102

"Comprehensive guide to tuning the Mercedes M102 engine!"

Our friends at TorqueCars are frequently seeing threads about how to improve the M102 from people wanting to know what are the best M102 modifications. So let us look into Mercedes M102 upgrades and outline the best modifications on this great engine and point out some problems along the way.

The Mercedes M102 are good project engines and with the ultimate uprated upgrades like ECU maps, turbo improvements and camshafts you will improve your driving fun.

This pages aim is look at M102 tuning and highlight the best modifications.

The ultimate M102 upgrades on an engine are sensibly the ones that give the biggest return for your money.

We won't be swayed by popular M102 upgrades, they need to be cost effective.

M102 induction kits

Improving air intake on the M102

You need air matched to fuel for an engine to work. If there is a lack 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 Forcing more air into each cylinder is the main goal to any performance tuning job.

You'll commonly see there's a limit in the air flow sensor MAP/MAF/AFM on the M102 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 sapped torque at a much lower level.

Intake manifolds carry the air flow during the suck phase from the filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.

Design and flow characteristics of the Air Intake manifolds can make a substantial effect on to fuel atomisation on the M102.

Most plenum chambers are ripe for motorsport parts, although a few OEM provide well optimised plenum chambers.

Big valve conversions on the M102, doing a bit of 3 or 5 angle valve jobs and porting and head flowing will also boost power, this will afford you an improved power increase on other tuning mods.

M102 performance cam tips.

Some M102 engines respond better to mild cam durations so view each engine as unique.

The engine timing and injectors and fuel pump also will make differences on the bhp gains you'll make.

A longer valve duration can alter the bhp 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.

Altering your M102 camshaft will make a dramatic difference to the engine bhp. Choosing a higher performance camshaft profile raises the bhp accordingly.

NB: Fast road cams tend to increase the bhp and torque across the rpm band, you may sacrifice a little bottom 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.

In a daily driver you should ideally to match your bhp range to your preferences.

You will never find a M102 Race cam is a pleasure to live with when driving around busy urban areas.

Stage 1, 2 and 3 mods for the M102

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 M102 parts:

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

Stage 2 M102 parts:

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

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

Stage 3 M102 parts:

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

The M102 engines are fantastic to work on and we see that there is a lot of mods and performance parts around.

Mapping should help to unlock the full potential of all the parts you've done to your M102.

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 results often depend much on the parts you've done and the condition of your engine.

Turbo modifications on the M102

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 M102.

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.

If a car has a turbocharger tuning parts are relatively easy and we find turbo engines are built with harder and stronger components.

However you will find an engines will need better parts at higher power limits

Research these limitations and fit better quality components to utilize the power.

It's not unheard of people spending a fortune on turbo upgrades on the M102 only to suffer the indignity of watching the motor go up in smoke when it's finished.

Large turbochargers commonly suffer no power at low rpm, and little turbochargers spool up really quickly but won't have the peak rpm engines power gains.

Thanks to progress the range of turbo units is always moving on and we now see variable vane turbo units, where the vane angle is altered according to speed to lower lag and increase top end power.

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

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

Tips about fuel supply on the M102

You will need to ensure that the engine is not starved of fuel so will need to ramp up the fuelling when you start going beyond 20% of a bhp and torque hike. It makes sense to over specify your flow rate on the injectors.

As a rule of thumb add 20% capacity when fitting an injector, helps cope with injector deterioration and provides a bit of 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 M102 performance exhaust upgrades

You may need to upgrade your exhaust system with an upgraded one is if the current exhaust is creating a flow problem.

On most factory exhausts you'll find the flow rate is still 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 from the engine but avoid an exhaust that is too wide or you could 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 catalysts installed, so adding a freer flowing high performance alternative will help avoid this restriction.

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

Faults issues and things to look out for on the M102

Like most engines an M102, 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 M102, failure to do this will exacerbate engine wear, on a tuned M102 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 M102 why not pop over to the forums at TorqueCars where you can chat about M102 tuning options and read about others projects who may be planning to do similar modifications on their M102.

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 M102, 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