Tuning the Mercedes M285

"Comprehensive guide to tuning the Mercedes M285 engine!"

We are always seeing threads requesting information on the best M285 power upgrades. So let us look into Mercedes M285 upgrades and outline the best modifications on this great engine and point out some common pitfalls along the way.

The Mercedes M285 are fantastic to work on and with carefully picked uprated upgrades like remaps, turbo upgrades and camshafts you will positively enhance your driving experience.

Here we review and look at M285 tuning and provide tips on the best mods that work.

Just because particular tuning mods are popular with M285 owners it doesn't mean its worth having, instead we will focus tuning mods that will give your M285 the best power gain for you money.

Altering your M285 cam will make a dramatic difference to the engine power band. Choosing a higher performance cam profile raises the power band accordingly.

NB: Fast road camshafts usually push up the torque over the rev band, you could sacrifice a little low end bhp but higher rpm power will be higher.

Competition camshafts, push up the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a daily driver must carefully try to match your power band to your driving style.

You'll never have ever thought a M285 Motorsport cam is a pleasure to live with when driving around busy urban areas.

Different M285 engines respond better to mild camshaft durations so set your engine up on a rolling road.

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

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.

M285 Tuning Stages

Stage 1 M285 modifications: Drilled & smoothed airbox, Fast road camshaft, Remaps/piggy back ECU, Intake headers, Panel air filters, Sports exhaust manifold.

Stage 2 M285 modifications: high flow fuel injectors, induction kit, Fast road cam, Ported and polished head, fuel pump upgrades, Sports catalyst & performance exhaust.

Stage 3 M285 modifications: Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Competition cam, Engine balancing & blueprinting, Internal engine upgrades (head flowing porting/bigger valves).

Plan your options and then buy your mods and set yourself a power target to avoid wasting your time and money.

Mapping will help to establish the full potential of all the modifications you've done to your M285.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved may vary depending on the modifications you've applied and the condition of your engine.

Forcing air and fuel into your M285 is the aim to any engine performance tuning project.

Air Intake manifolds transmit the air from the intake filter and allow it to be sucked into the engine and mixed with fuel.

The shape and flow rate of the Plenum can make a substantial difference to to fuel atomisation and engine efficiency on the M285.

Commonly we find the intake are ripe for aftermarket tuning parts, although some makers provide well optimised intake.

Fitting big valve kits, doing a bit of port matching and head flowing will also boost bhp and torque, & importantly will afford you an improved bhp and torque increase on other upgrades.

Turbo upgrades for the M285

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 M285

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes impressive power gains.

When your motor has forced induction modifications are giving better power gains and most turbo engines are built using many forged and stronger components.

However engines will have power limits

It is important to find these restrictions and fit better quality components to handle the power.

We see many car owners spending a loads on turbo charger upgrades on the M285 only to experience the motor literally blow up when it's first rolling road session.

Bigger upgraded turbo chargers often experience low end lag, and small turbo chargers spool up more quickly but don't have the top end torque gains.

Thanks to progress the selection of turbo chargers is always evolving and we commonly find variable vane turbo chargers, where the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbo chargers divert the exhaust gases into two channels and flow these at differently angled vanes in the turbo. They also increase 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 M285 when loads more air is being pulled into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited power at a much lower level.

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

Uprating M285 fuel injectors

You will need to ensure that the engine is not starved of fuel so will need to pay attention to the fuelling when you start extending past 20% of a performance increase.We strongly recommend you to over specify your injectors flow rate.

The accepted safe increase is to add another 20% when fitting an injector, this takes into account injector deterioration and provides 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 M285 performance exhausts

You only need to to replace your exhaust if your current exhaust is actually creating a flow problem.

On most factory exhausts you'll see your flow rate is still fine 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 through the engine but do not go too big or you could will reduce the flow rate. Stick to 1.5 to 2.5 inches as a rule of thumb.

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

Problems and issues to look out for on the M285

The M285 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M285, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M285 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M285 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 M285 guides and tips are kept up to date.

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