Tuning the Mercedes M274

"Comprehensive guide to tuning and performance parts on the Mercedes M274 engine!"

We are regularly seeing threads asking how to improve the M274 from people wanting to know what are the optimum M274 upgrades. So let us look into Mercedes M274 parts and outline the best modifications on this great engine and point out some common pitfalls along the way.

Now we will review M274 tuning and summarise the optimum modifications. Mercedes M274 are popular engines and with a few sensible modified upgrades like remapping, turbo improvements and camshafts you will substantially maximize your driving enjoyment.

Just because particular upgrades are popular with M274 owners it doesn't mean you should fit it, we shall ultimate upgrades that will give your M274 the best power gain for you money.

Significant gains on the M274 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

NB: Fast road camshafts normally bump the torque throughout the rpm range, you could drop a little low down bhp but your higher rpm power will be higher.

Motorsport and race camshafts, bump the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Race cam won't do well if on the daily commute.

You should ideally match your bhp range to your driving style so for a car used daily stick with a mild fast road M274 cam

Each engine responds better to more or less aggressive cam durations check your engine on a rolling road.

The ECU mapping and fuelling also have a large bearing on the torque gains you'll hit.

Altering 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.

M274 Tuning Stages

Stage 1 M274 modifications: Sports exhaust manifold, Panel air filters, Fast road camshaft, Remaps/piggy back ECU, Intake headers, Drilled & smoothed airbox.

Stage 2 M274 modifications: fuel pump upgrades, Ported and polished head, Fast road cam, high flow fuel injectors, Sports catalyst & performance exhaust, induction kit.

Stage 3 M274 modifications: Internal engine upgrades (head flowing porting/bigger valves), Twin charging conversions, Crank and Piston upgrades to alter compression, Competition cam, Engine balancing & blueprinting, Adding or Upgrading forced induction (turbo/supercharger).

Remaps helps unlock the full potential of all the parts you've done to your M274.

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

Shoving more air and fuel into the M274 engine is vital to any tuning job.

The intake plenum transmit the air during the suck phase from the intake filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.

The size of bore and shape and rate of flow of the Intake manifold can make a substantial change to fuel mixing and power on the M274.

It's not uncommon that air intake manifolds are ripe for performance upgrades, although some makers provide fairly well optimized air intake manifolds.

Adding a M274 larger valve kit, getting port work and head flowing will also improve bhp and torque, and as an added benefit will make space for a better bhp and torque increase on other tuning parts.

Turbo upgrades for the M274

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 M274

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

If your motor is turbocharged, parts are more reliable and turbo charged engines are made with better components.

There are tuning limits for every engine, with some being incredibly solid and some only just able to handle stock power

It is important to find these limits and upgrade to higher quality components to survive the power.

It's not unheard of guys spending a fortune on turbocharger upgrades on the M274 only to suffer the humiliation of seeing the motor catastrophically fail on it's first outing after it's used on the roads.

Bigger upgraded turbo chargers tend to suffer a bottom end lag, and little turbo chargers spool up really quickly but won't have the top end torque gains.

We are pleased that the range of turbo units is always evolving and we are seeing variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end performance.

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

You'll commonly see there is a limitation in the air flow sensor MAP/MAF/AFM on the M274 when considerably more air is being sucked into the engine.

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

Adding a supercharger or additional turbo will make large performance gains, although more difficult to get working. We have this in depth look at twinchargers if you want to read more.

Uprating M274 fuel injectors

Don't miss you'll need to ramp up the fuelling when you are increasing the bhp and torque - it makes the car more thirsty. We strongly recommend you to be generous with your injectors flow rate.

The accepted safe increase is to add 20% capacity when buying an injector, this accounts for injector deterioration and gives a little 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 M274 performance exhausts

You should look to boost your exhaust if the existing exhaust is actually causing a flow problem.

On most factory exhausts you'll see the exhaust 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 generally help improve air flow from the engine but avoid an exhaust that is too large or you may end up will reduce the flow rate. Stick to 1.5 to 2.5 inches as a rule of thumb.

Typically exhaust restrictions can be located the catalysts installed, so adding a higher flowing sports alternative will help avoid this restriction.

Problems and issues to look out for on the M274

The M274 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M274, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M274 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M274 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 M274 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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