Tuning the Mercedes M278

"Comprehensive guide to tuning the Mercedes M278 engine!"

We are frequently getting emails asking how to improve the M278 from people wanting to know what are the best M278 power upgrades. So let us look into Mercedes M278 parts and outline the best modifications on this great engine and point out some potential pitfalls along the way.

Now we shall outline options for your M278 tuning and show the best modifications. Mercedes M278 are fantastic to work on and with the optimum performance upgrades like remapping, turbo kits and camshafts you will definitely maximise your driving pleasure.

The best M278 mods on an engine are in our opinion the ones that give the best value for money.

We won't be swayed by popular M278 mods, they need to be cost effective.

Significant gains on the M278 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the engines power and power output.

NB: Fast road cams commonly boost the performance over the rev band, you could drop a little bottom end power but the top end will be better.

Competition 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 road car should ideally to optimize your engines power to your cars usage.

I'd be gobsmaked if you find a M278 Motorsport camshaft is a pleasure to live with when driving in heavy traffic.

Some M278 engines respond better to more or less aggressive camshaft durations check your engine on a rolling road.

The map and fuel pump and injectors also have a large bearing on the torque gains you'll get.

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.

M278 Tuning Stages

Stage 1 M278 modifications: Sports exhaust manifold, Fast road camshaft, Intake headers, Panel air filters, Drilled & smoothed airbox, Remaps/piggy back ECU.

Stage 2 M278 modifications: Sports catalyst & performance exhaust, Fast road cam, fuel pump upgrades, Ported and polished head, induction kit, high flow fuel injectors.

Stage 3 M278 modifications: Engine balancing & blueprinting, Internal engine upgrades (head flowing porting/bigger valves), Crank and Piston upgrades to alter compression, Competition cam, Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions.

Remaps allows a tuner to fully realize the full potential of all the parts you've done to your M278.

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

Pushing air into your M278 is the main goal to any car tuning job.

The intake plenum carry the air during the suck phase from the filter and allow it to be sucked into the engine cylinders.

Design and flow rate of the Intake can make a big change to fuel delivery on the M278.

Most plenum chambers are in dire need of performance upgrades, although some manufacturers provide well optimised plenum chambers.

Big valve conversions on the M278, getting port matching and head flowing will also lift bhp and torque, and as an added benefit will give you raising the bhp and torque increase on other modifications.

Turbo upgrades for the M278

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 M278

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 the engine is turbocharged, parts are more reliable and you will discover turbo charged engines use uprated components.

However every engines have weakspots

We recommend you find these limitations and fit better quality crank and pistons to utilize the power.

It's not unheard of people spending a fortune on turbocharger upgrades on the M278 only to suffer the humiliation of seeing the M278 go up in smoke when it's been finished.

Bigger upgraded turbos commonly suffer no power at low rpm, and smaller turbos spool up really quickly but do not have the peak end torque gains.

Thanks to progress the world of turbo chargers is always developing and we are seeing variable vane turbo chargers, permitting the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

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

It is common that there is a restriction in the air flow sensor AFM/MAP on the M278 when considerably more air is being sucked into the engine.

Going up you'll find 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 bhp and torque gains, although more challenging to get working. We have this guide to twinchargers if you want to read more.

Uprating M278 fuel injectors

When you increase the power you will need to ramp up to the fuelling.

More power needs more fuel. Most tuners we speak with say to be generous with your injector capacity.

The rule of thumb is to add 20% capacity when fitting an injector, which takes into account injector deterioration and affords 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.

Best M278 performance exhausts

Only look to upgrade your exhaust if the current exhaust is actually creating a flow problem.

On most factory exhausts you'll find your 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 help balance the flow of air through the engine.

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

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

Problems and issues to look out for on the M278

The M278 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M278, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M278 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M278 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 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 M278 guides and tips are kept up to date.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Mercedes. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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