Mercedes M102 Tuning

"All you need to know about tuning and performance parts on the Mercedes M102 engine!"

TorqueCars will examine M102 tuning and summarise the premier modifications for your car. Mercedes M102 engines are great bases for a tuning project and with carefully picked modifications like remaps, turbo upgrades and camshafts you will certainly increase your driving opportunities.

Cosworth showed the way when they took this block and finely honed and fettled it, inspiring many tuners to explore the potential of the M102 engine block.

It certainly is a very solid block and the number of revisions over the years have allowed frankenbuilds where heads from later models are fitted to early ones, and bottom end swaps can be carried out.

So let's start by looking at how the engine was revised and evolved over the years.

History, Power & Specs of the Engine

M102.910

  • (1.8 L).  80 kW (109 PS; 107 bhp) .Torque: 154 Nm (114 lbft)

Applications:

1990-1993 W201 180E and 190E 1.8

M102.920

  • (2.0 L).  80 kW (109 PS; 107 bhp). Swedish and Swiss market 98 PS (72 kW) at 5000 rpm for stricter emissions regulations.

Applications:

1980-1986 W123 200
1980-1986 W123 200T

M102.921

  •  66 kW (90 PS; 89 bhp)

Applications:

1983-1985 W201 190 (201.022)

M102.922

  • (2.0 L). 80 kW (109 PS; 107 bhp).

Applications:

1985-1992 W124 200

M102.924

Similar to M102.921, Power output: 77 kW (105 PS; 103 bhp).

Application

1986-1990 W201 190 (201.023)

M102.938

  • Low compression 63 kW (86 PS; 84 bhp).

Application

W201 190

M102.939

  • Low compression  74 kW (101 PS; 99 bhp).

Application

W123 200
W123 200T

M102.961

  • A 2.0 L 90 kW (122 PS; 121 bhp)

Application

1983-1985 W201 190E

M102.962

  • (2.0 L). 87 kW (118 PS; 117 bhp)

Applications:

1985-1993 W201 190E

M102.963

  • 2.0 L 90 kW (122 PS; 121 bhp)

Applications:

1985-1992 W124 200E

M102.964

  • 2.0l  90 kW (122 PS; 121 bhp)

Applications:

1986-1989 W460 200GE.

M102.980

  • 2.3 L 100 kW (136 PS; 134 bhp)

Applications:

1980-1986 W123 230E
1980-1986 W123 230CE
1980-1986 W123 230TE

M102.981

  • 2.3 L 92 kW (125 PS; 123 bhp)

Applications:

1979-1989 W460 230GE Geländewagen

M102.982

  • KE-Jetronic system Bosch. 97 kW (132 PS; 130 bhp)

Applications:

1985-1992 W124 230E
1985-1992 W124 230CE
1985-1992 W124 230TE

M102.983

  • A 16-valve M102.985 138 kW (188 PS; 185 bhp); US: 125 kW (170 PS; 168 bhp)

Applications:

1986-1987 W201 190E 2.3-16

M102.985

  • An 8v 2.3 L 97 kW (132 PS; 130 bhp)

Applications:

1985-1992 W201 190 E 2.3

M102.990

  • 16-valve (2.5 L) 150 kW (204 PS; 201 bhp)

Applications:

1988-1993 W201 190E 2.5-16

M102.991

  • 2.5 16-valve version, 147 kW (200 PS; 197 bhp)

Applications:

1989 W201 190E 2.5-16 Evolution

M102.992

  • (2.5 L).  173 kW (235 PS; 232 bhp)

Applications:

1990 W201 190E 2.5-16 Evolution II

Tuning the Mercedes M102 and best M102 performance parts. The recent 2.5 engine blocks, especially those tweaked by Cosworth allow for very large power gains, but this shows what can be done on the early M102 engines to bring them up to spec.

Best M102 parts

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

There is an interesting mod you can do on the EZL ignition modules where the resistor (R16) is changed and this causing an ignition advance. Do not remove this resistor or you'll get  no advance and a fault condition.

Also do not assume the greatest value  of resistance is best, it does not suit all engines and driving conditions. We suggest you range from 220ohm 470ohm 750ohm 1300ohm and 2400ohm and see which works, checking the timing advance with a strobe and driving. Fuel type can also have an effect on this.

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 torque gains are on offer for cam upgrades.

Fast road camshafts usually boost the torque through the rpm band, you could drop a little low end bhp but the top end will be lifted.

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

In a road car must carefully try to optimize your power band to your preferences.

I'd be completely gobsmacked if you have found a M102 Competition cam is a pleasure to live with when driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

Each engine responds better to more or less aggressive cam durations than others.

The ECU mapping and fuel pump and injectors also will say much on the power gains you'll make.

Extending exhaust or intake 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, Fast road camshaft, Intake manifolds, Sports exhaust header/manifold, drilled & smoothed airboxPanel air filters.

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

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

Carefully think through your options and then buy your modifications and set yourself a power target to avoid costly mistakes.

remap will help fully realize the full potential of all the mods you've done to your M102.

(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 end result will rely on the mods you've carried out and the condition of your engine.

It is the main goal to any tuning task to feed fuel and air into your M102

Intake manifolds transmit the air during the suck phase from the intake filter and allow it to be fed into the engine and mixed with fuel.

The bore size, shape and flow rate of the Intake can make a noticeable difference to fuel atomisation on the M102.

Most plenum chambers are in dire need of a performance upgrade, although a few makers provide reasonably well designed plenum chambers.

Larger M102 valves, getting port work and head flowing will also improve power, and significantly will give you raising the power increase on other parts.

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 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 major power gains.

If a car has a turbocharger tuning mods are simpler to install and we find turbocharged engines already contain more solid components.

However you'll find engines have weakspots

Discover these restrictions and upgrade to higher quality crank and pistons to handle the power.

We see many guys spending a loads on turbocharger upgrades on the M102 only to see the car throw a rod when it's first rolling road session.

Large upgraded turbo units tend to suffer low end lag, and small turbo units spool up really quickly but don't have the peak rpm engines power gains.

In recent times the range of turbos is always improving and we now see variable vane turbos, permitting the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbos divert the exhaust flow into two channels and push these at differently designed vanes in the turbocharger. They also boost the scavenging effect of the engine.

Rather than buy a turbo kit, or expensive turbo parts, we've seen projects where a Mercedes turbo from say the 220CDi have been retrofitted, and the only major cost is time as the parts are readily available in the breakers yard. Do watch your compression ratios though and have a plan to sort out the mapping.

It is not unusual that there is a limitation in the air flow sensor MAP/MAF/AFM on the M102 when considerably more air is being drawn into the engine.

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

Adding a supercharger or additional turbo will make large power gains, although harder to setup. We have this in depth look at twinchargers if you want to read more.

Fuelling

When you boost the torque you will need to look at to the fuelling.

More torque needs more fuel. It makes sense to be generous with your injectors flow rate.

As a rule of thumb add 20% when buying an injector, this takes into account injector deterioration and allows a bit of spare capacity should the engine require 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.

Converting from Carb to the KE Jetronic system will really help lift the engines efficiency and power.

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

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

Exhaust

Only look to replace your exhaust if your current exhaust is actually causing a flow problem.

On most factory exhausts you'll see the exhaust 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 can usually air flow through the engine but do not go too wide or you could very well end up with a reduced flow rate. So generally speaking, keep to 1.5 to 2.5 inches for best results.

Usual exhaust restrictions are in the catalyst and filters installed, so adding a freer flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

Weak spots, Issues & problem areas on the M102

The M102 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.

Please let us know if there are any other problems or issues we have missed. with most running to 150,000 miles before needing major work.

Regular oil changes are vital on the M102, especially when tuned and will help extend the life and reliability of the engine.

On early models there was an issue with the timing chain and the intermediate gear that drives the distributor. These wear out because of a design fault but this was rectified in the later models with a double timing chain and most early engines have been repaired by now.

If you would like to know more, or just get some friendly advice 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.

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 M102 tuning guides which get regular updates and revisions.

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One Response to “M102 Tuning”

  1. mr james clelland says:

    Hi, before I start tuning just a bit, if you know that is. I’ve two 190E’s (both M102) and one I plan a mild tune the other I’d take further. The cosworth’s had strengthening ribs in the block, both of mine are 1993 models, would they have inherited the same ?

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