Tuning the Mercedes M102

"Comprehensive guide to tuning the Mercedes M102 engine!"

We are frequently seeing threads requesting information on the best tips on M102 modifications. So let us look into Mercedes M102 modifications and outline the best modifications on this great engine and point out some problems along the way.

Our aim here is to provide a guide to M102 tuning and summarise the greatest modifications for your car. Mercedes M102 great bases for a tuning project and with the optimum uprated upgrades like ECU maps, turbo upgrades and camshafts you will substantially enhance your driving experience.

When talking about the best parts for your M102 engine, we are going to concentrate on the upgrades that give the best power gain for you spend.

Significant gains on the M102 can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

NB: Fast road cams commonly bump the torque through the rev range, you may sacrifice a little low end power but the high end rpm power will improve.

Motorsport and race cams, bump the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a car driven daily you need to match your engines power to your typical driving style.

I'd be shocked if you have ever thought a M102 Motorsport cam is a pleasure to live with when driving in heavy traffic.

Each engine responds better to less aggressive camshaft durations than others.

The map and fuel pump and injectors also have an effect on the bhp gains you'll make.

Longer valve durations 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.

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Guide to the best M102 tuning mods & Upgrades

  1. ECU Map Tuning & Remaps

    Some cars may require a piggyback ECU's or aftermarket ECU's to change the OEM map, but remapping is the most vital step of your tuning project to fully maximise your mods. Expect 10-20% on NASP engines and 30-40% on turbocharged units.

  2. Strengthen Your Engine

    Tuned cars will show up weaknesses, typically in the turbochargers, clutch and internal engine components. Whilst most engines can cope with mild tuning mods, TorqueCars recommend that you upgrade the internal components before these weak spots manifest themselves.

  3. Mods that Remove a Restriction

    A restricted intake or exhaust will have an impact on your performance, so use a better flowing air filter/induction kit and better flowing exhaust (sports cats where legal are a good option) whenever your tuning creates a flow restriction. Turbo engines also benefit from intercooler upgrades as these resist heat soak for longer periods of time.

  4. Mods that Improve Fuelling

    Every tuning project will aim to increase the air supply, but fuel supply is just as vital and will need to match the air the engine can utilise,  a fuel pump and injector upgrade are usual mods, but also in many cases the fuel regulator will need improvement.

  5. Mods to Provide better Airflow

    Increasing the air supply is just as essential as improving fuelling, we suggest you look at head mods (flowing and porting, 5 angle valve jobs), fit bigger valves, fast road cams and forced induction upgrades (adding a better flowing turbo) to improve air intake.

M102 Tuning Stages

Stage 1 M102 modifications: Drilled & smoothed airbox, Fast road camshaft, Intake headers, Sports exhaust manifold, Panel air filters, Remaps/piggy back ECU.

Stage 2 M102 modifications: fuel pump upgrades, high flow fuel injectors, induction kit, Sports catalyst & performance exhaust, Fast road cam, Ported and polished head.

Stage 3 M102 modifications: Engine balancing & blueprinting, Twin charging conversions, Competition cam, Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves), Crank and Piston upgrades to alter compression.

Plan your options and then acquire your upgrades and set yourself a power target to save yourself from expensive mistakes.

ECU flashing should help to to establish the full potential of all the modifications you've done to your M102.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results will depend much on the modifications you've carried out and the condition of your engine.

Pulling more fuel and air into each cylinder is the main goal to any engine performance tuning task.

Intake 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 rate of flow of the Intake headers can make a noticeable change to fuel delivery on the M102.

I usually find intake are needing a performance upgrade, although some makers provide reasonably well designed intake.

Larger M102 valves, getting port matching and head flowing will also lift power, and as an added benefit will make space for raising the power increase on other upgrades.

Turbo upgrades for the M102

NASP 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 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 massive power gains.

If an engine is turbocharged, upgrades are giving better power gains and you'll see that turbo engines use better components.

However most engines will have power limits

See where you'll find these limitations and fit higher quality crank and pistons to utilize the power.

We see many people spending a loads on turbocharger upgrades on the M102 only to see the whole thing catastrophically fail on it's first outing after it's finished.

Big upgraded turbo units commonly experience low end lag, and small turbo units spool up quickly but do not have the peak end engines power gains.

In the last 10 years the selection of turbos is always developing and we now see variable vane turbos, where the vane angle is altered according to speed to lower lag and increase top end torque.

Twin scroll turbos divert the exhaust flow into two channels and direct these at differently profiled vanes in the turbo charger. They also increase the scavenging effect of the engine.

It is not unusual that there's a limitation in the air flow sensor MAF/MAP on the M102 when loads more air is being fed into the engine.

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

Adding a supercharger or additional turbo will make large power gains, although more difficult to configure. We have this article on twincharging if you want to read more.

Uprating M102 fuel injectors

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

As a rule of thumb add another 20% when fitting an injector, this takes into account 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.

Best M102 performance exhausts

You should look to uprate your exhaust if the existing exhaust is creating a flow problem.

On most factory exhausts you should find that your flow rate is still 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 generally help improve air flow from the engine but do not go too wide or you may end up will reduce the flow rate. Stick to 1.5 to 2.5 inches as a rule of thumb.

Usual exhaust restrictions are in the filters installed, so adding a faster flowing performance alternative will help avoid this restriction.

Problems and issues to look out for on the M102

The M102 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M102, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M102 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M102 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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

We really like hearing from our readers, and hearing about which upgrades were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our M102 guides and tips are kept up to date.

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