Tuning the Mercedes M111

"Comprehensive guide to tuning the Mercedes M111 engine!"

We are always getting posts asking how to improve the M111 from people wanting to know what are the ultimate M111 modifications. So let us look into Mercedes M111 parts and outline the best modifications on this great engine and point out some potential pitfalls along the way.

Let us provide a guide to M111 tuning and highlight the premier modifications. Mercedes M111 are popular tuning projects and with the ultimate modified modifications like a remap, turbo improvements and camshafts you will noticeably maximise your driving pleasure.

When talking about the top parts for your M111 engine, we are going to focus on the parts that give the biggest return for your cash.

Significant gains on the M111 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

NB: Fast road cams commonly boost the power throughout the rev range, you could sacrifice a little low end power but the top end will improve.

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

In a car used daily one should, ideally, try to match your engines power to your usage of the car.

I'd be gobsmaked if you have ever thought a M111 Motorsport camshaft is a pleasure to live with when driving around busy urban areas.

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

The engine timing and injectors and fuel pump also have a large bearing on the torque gains you'll hit.

Longer 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.

M111 Tuning Stages

Stage 1 M111 modifications: Sports exhaust manifold, Drilled & smoothed airbox, Fast road camshaft, Intake headers, Panel air filters, Remaps/piggy back ECU.

Stage 2 M111 modifications: fuel pump upgrades, high flow fuel injectors, Ported and polished head, Sports catalyst & performance exhaust, Fast road cam, induction kit.

Stage 3 M111 modifications: Competition cam, Internal engine upgrades (head flowing porting/bigger valves), Twin charging conversions, Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Crank and Piston upgrades to alter compression.

The M111 engines make great tuning projects and we're happy to report there is an increase of modifications and performance parts out there.

Remaps should help to fully realize the full potential of all the upgrades you've done to your M111.

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 vary depending on the upgrades you've carried out and the condition of your engine.

It is the main goal to any tuning project to pull air and fuel into each cylinder

Intake carry the air from the air filter and allow it to be pulled into the engine cylinders.

Structure and flow rate of the Headers can make a big difference to to fuel engine efficiency on the M111.

Commonly we find the intake manifold are needing performance upgrades, although some OEM provide reasonably well designed intake manifold.

Fitting big valve kits, doing a bit of port matching and head flowing will also raise performance, this will raise potential for increasing the performance increase on other tuning parts.

Turbo upgrades for the M111

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 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 superb power gains.

When your car is fitted with a turbocharger upgrades are going to make more power and most turbo engines are made with better components.

However engines will have power limits

See where you'll find these limitations and fit better quality crank and pistons to cope with the power.

There are many people spending a loads of money on turbo charger upgrades on the M111 only to have the whole thing go up in smoke just after it's been completed.

Bigger upgraded turbo units commonly suffer low end lag, and low capacity turbo units spool up much more quickly but do not have the peak rpm torque gains.

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

Twin scroll turbo chargers divert the exhaust gases into a couple of channels and feed these at differently designed vanes in the turbo charger. They also improve the scavenging effect of the engine.

It is common that there's a restriction in the air flow sensor (AFM/MAF/MAP) on the M111 when a lot more air is being drawn into the engine.

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

Adding a supercharger or additional turbo will make large torque gains, although harder to install. We have this feature on twinchargers if you want to read more.

Uprating M111 fuel injectors

Don't overlook the need to improve the fuel system when you are increasing the torque - it makes the car more thirsty. Don't forget to be generous with your injector capacity.

The rule of thumb is to add another 20% when specifying an injector, helps cope with injector deterioration and gives you some 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.

Best M111 performance exhausts

You only need to to boost your exhaust if your current exhaust is creating a restriction in flow.

On most factory exhausts you should find that the flow rate is good 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 increase the flow of gases through the engine.

But if your exhaust is too big, ie: over 2.5 inches bore, you will lose a great deal of the exhaust flow rate and end up lacking power and torque.

Typically exhaust restrictions are in the filters installed, so adding a better flowing race alternative will help avoid this restriction.

Problems and issues to look out for on the M111

The M111 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M111, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M111 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M111 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 M111 guides and tips are kept up to date.

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