Everything You Need To Know About "M278 Modifications"

How to modify and upgrade the Mercedes M278

"Comprehensive guide to tuning and performance parts on the Mercedes M278 engine!"

TorqueCars are frequently getting messages asking about how to improve the M278 from people inquiring about getting more power from the M278 and wanting to know what are the best tips on M278 upgrades. So let us look into Mercedes M278 tuning mods and outline the best modifications on this great engine and point out some potential pitfalls along the way.

The Mercedes M278 provide a fun base for your project and with the ultimate motorsport upgrades like a remap, turbo upgrades and camshafts you will substantially maximise your driving fun.

Let us review and look at M278 tuning and point out the premier modifications.

Just because particular upgrades are popular with M278 owners it doesn't mean its worth having, instead we'll concentrate on the best upgrades that will give your M278 the biggest power gain return for your cash.

Without us subscribing to the popular mentality of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

Improving air intake on the M278

You need air matched to fuel for an engine to work. If there is a lack of fuel then it will run lean, if there is not enough air it runs rich losing power and potentially damaging the engine. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Feeding more fuel and air into each cylinder is the primary aim to any engine modification task.

It is not unusual that there is a limitation in the air flow sensor MAP/MAF/AFM on the M278 when considerably 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 bhp and torque at a much lower level.

The intake plenum transmit the on the suck phase from the air filter and allow it to be pulled into the engine cylinders.

Shape and rate of flow of the Intake headers can make a noticeable difference to to fuel mixing and power on the M278.

Many mass produced engine headers are needing aftermarket parts, although a few makers provide fairly well optimized headers.

Larger M278 valves, doing some M278 port enlargement and head flowing will also boost bhp and torque, & more importantly will give you a better bhp and torque increase on other tuning mods.

M278 performance cam tips.

Each engine responds better to extreme camshaft durations so set your engine up on a rolling road.

The map and fuelling also have an effect on the torque gains you'll hit.

A longer valve duration 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.

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 engines power gains are on offer for cam upgrades.

NB: Fast road cams commonly increase the bhp across the rev band, you may sacrifice a little low down power but the high end rpm power will be higher.

Motorsport cams, increase the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport and race camshaft will just annoy you whilst driving in heavy traffic.

You should ideally optimize your bhp range to your cars usage so for a road car stick with a fast road M278 camshaft

Stage 1, 2 and 3 mods for the M278

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

1. Suspension Upgrades - always improve your cars handling
2. Brake Upgrades - Even before adding power improve those brakes
3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
6. Fuelling - when you've increased power you'll need to match this with more fuel
7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 M278 parts:

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

Stage 2 M278 parts:

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

Stage 3 M278 parts:

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

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

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage will differs on the tuning parts you've applied and the condition of your engine.

Turbo modifications on the M278

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the 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 your car is turbo charged parts are giving better power gains and we find turbocharged engines already contain stronger components.

There are reliable limits for every engine, with some being over specified and some only just able to handle stock power

Discover these restrictions and install more solid crank and pistons to handle the power.

We see many people spending a lot of money on turbocharger upgrades on the M278 only to see the car go up in smoke on it's first outing after it's first rolling road session.

Large turbo units will usually suffer low end lag, and little turbo units spool up quickly but don't have the peak rpm power band gains.

Thankfully the market of turbo units is always improving and we commonly find variable vane turbo units, permitting the vane profile is altered according to speed to lower lag and increase top end performance.

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

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large bhp gains, although more difficult to install. We have this guide to twinchargers if you want to read more.

Tips about fuel supply on the M278

When you lift the performance you will need to ramp up to the fuel system.

More performance needs more fuel. Experienced tuners recommend to be generous with your flow rate on the injectors.

The rule of thumb is to add 15% when buying an injector, this accounts for injector deterioration and provides a little spare capacity should the engine require more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended M278 performance exhaust upgrades

Only look to increase your exhaust system with an upgraded one is if your current exhaust is actually causing a restriction.

On most factory exhausts you'll see the exhaust flow rate is ok even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts will certainly help air flow through the engine but do not go too large or you may end up will reduce the flow rate. Stick to one and a half to two and half inches for best results.

The usual suspects causing problems in your exhaust flow rate are in the filters installed, so adding a freer flowing race alternative will help avoid this restriction.

Decats (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the M278

Like most engines an M278, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the M278, failure to do this will exacerbate engine wear, on a tuned M278 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your M278 why not pop over to the forums at TorqueCars where you can chat about M278 tuning options and read about others projects who may be planning to do similar modifications on their M278.

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This entry was posted under Makes and Models. Tags: engine, mercedes
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