Tuning the Mercedes M133

"Comprehensive guide to performance tuning the Mercedes M133 engine!"

We often are seeing threads requesting information on the best M133 power upgrades. So let us look into Mercedes M133 upgrades and outline the best modifications on this great engine and point out some common pitfalls along the way.

Let us examine the options for your M133 tuning and highlight the ultimate mods that work. Mercedes M133 are good project engines and with carefully chosen motorsport tuning mods like ECU maps, turbo improvements and camshafts you will certainly increase your driving opportunities.

Just because particular tuning parts are popular with M133 owners it doesn't mean its worth having, so we'll best tuning parts that will give your M133 the best power gain for you money.

Altering your M133 cam will make a dramatic difference to the engine bhp. Choosing a higher performance cam profile raises the bhp accordingly.

NB: Fast road cams commonly raise the performance through the rev band, you may sacrifice a little bottom end power but higher rpm power will be higher.

Motorsport cams, raise the higher 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 optimize your power band to your typical driving style.

I'd be gobsmaked if you find a M133 Motorsport and race cam is a pleasure to live with when driving around busy urban areas.

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

The ECU mapping and fuel pump and injectors also have a large bearing 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.

M133 Tuning Stages

Stage 1 M133 modifications: Remaps/piggy back ECU, Intake headers, Sports exhaust manifold, Drilled & smoothed airbox, Panel air filters, Fast road camshaft.

Stage 2 M133 modifications: induction kit, Sports catalyst & performance exhaust, fuel pump upgrades, high flow fuel injectors, Ported and polished head, Fast road cam.

Stage 3 M133 modifications: Adding or Upgrading forced induction (turbo/supercharger), Crank and Piston upgrades to alter compression, Twin charging conversions, Competition cam, Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting.

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

Remaps should help to fully realize the full potential of all the parts you've done to your M133.

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

It is the whole point to any car tuning project to feed more air and fuel into the M133 engine

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

Design and flow characteristics of the Headers can make a big improvement to fuel delivery on the M133.

Many mass produced engine air intake manifolds are needing performance upgrades, although some car makers provide decently flowing air intake manifolds.

Larger M133 valves, doing some port work and head flowing will also raise power, & more importantly will make space for increasing the power increase on other mods.

Turbo upgrades for the M133

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 M133

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.

If your car is turbo charged mods are giving better power gains and you'll see that turbo charged engines use stronger components.

There are common areas of failure for every engine, with some being incredibly solid and some only just able to handle stock power

It is important to find these limitations and install higher quality crank and pistons to survive the power.

We've seen car owners spending a lots of money on turbo upgrades on the M133 only to suffer the humiliation of seeing the engine block literally blow up soon after it's been enthusiastically driven.

Big capacity turbochargers tend to suffer a bottom end lag, and small turbochargers spool up really quickly but don't have the top end torque gains.

In recent times the selection of turbos is always increasing and we now see variable vane turbos, allowing the vane angle is altered according to speed to lower lag and increase top end bhp.

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

It is not unusual that there's a restriction in the air flow sensor MAP/MAF/AFM on the M133 when loads more air is being pulled into the engine.

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

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

Uprating M133 fuel injectors

When you increase the bhp you will need to uprate to the fuelling.

More bhp needs more fuel. Don't forget to be generous with your injector capacity.

The rule of thumb is to add another 20% when specifying an injector, which takes into account injector deterioration and allows a bit of 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 M133 performance exhausts

You only need to to increase your exhaust if your current exhaust is actually causing a restriction in flow.

On most factory exhausts you'll find your flow rate is still 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 will certainly help air flow through the engine but avoid an exhaust that is 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.

Common exhaust restrictions can be traced to the catalyst and filters installed, so adding a freer flowing performance alternative will help avoid this restriction.

Problems and issues to look out for on the M133

The M133 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M133, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M133 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M133 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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We really like hearing from our readers, and hearing about which tuning parts were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our M133 guides and tips are kept up to date.

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