Tuning guide "M271 Modifications"

M271 Modifications Guide

How to modify and upgrade the Mercedes M271

"Comprehensive guide to tuning and performance parts on the Mercedes M271 engine!"

Our friends at TorqueCars are frequently getting messages asking how to improve the M271 from people wanting to know what are the best M271 modifications. So let us look into Mercedes M271 upgrades and outline the best upgrades on this great engine and point out some problems along the way.

The Mercedes M271 provide a fun base for your project and with the best performance parts like ECU maps, turbo kits and camshafts you will certainly increase your driving enjoyment.

In this article we review and look at M271 tuning and summarise the greatest modifications.

When talking about the ultimate parts for your M271 engine, we are going to concentrate on the upgrades that give the best power gain for you spend.

M271 induction kits

Improving air intake on the M271

You need fuel and air for an engine to work. If there is little supply of fuel then it will run lean, if there is a lack of air it runs rich sapping power which risks damage to the M271. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the whole point to any performance tuning project to pull more air and fuel into each cylinder but this has a knock on effect with the air flow sensor.

You'll commonly see there's a limit in the air flow sensor (AFM/MAF/MAP) on the M271 when considerably 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 limited bhp and torque at a much lower level.

Intake flow the air from the air cleaner and allow it to be sucked into the engine and mixed with fuel.

Shape and rate of flow of the Air Intake manifolds can make a noticeable improvement to fuel mixing and power on the M271.

Many mass produced engine air intake manifolds are begging for aftermarket parts, although a few car makers provide reasonably good air intake manifolds.

Fitting big valve kits, carrying out port work and head flowing will also boost performance, & importantly will give you a greater performance increase on other mods.

M271 performance cam tips.

Different M271 engines respond better to more or less aggressive camshaft durations than others.

The ecu map and fuelling also will make differences 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.

Significant air intake, and exhaust improvements on the M271 can be made from cam upgrades. Changing the cam profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

NB: Fast road cams tend to increase the bhp across the rev range, you could drop a little low end bhp but high end rpm power will be lifted.

Race 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 Race camshaft won't do well if driving in heavy traffic.

You should ideally match your engines power to your typical driving style so for a road car stick with a fast road M271 camshaft

Stage 1, 2 and 3 mods for the M271

Stage 1 M271 parts:

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

Stage 2 M271 parts:

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

Stage 3 M271 parts:

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

The M271 units are great to work on and we're pleased to see that there are plenty of parts and performance parts around.

A remap should help to unlock the full potential of all the upgrades you've done to your M271.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

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 results will depend much on the upgrades you've carried out and the condition of your engine.

Turbo modifications on the M271

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 M271.

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 upgrades are going to net you a larger power gain and you will discover turbo charged engines already contain stronger components.

However most engines will have power limits

See where you'll find these limits and upgrade to better pistons and crank to handle the power.

We see many car owners spending a a stack of money on turbocharger upgrades on the M271 only to watch the M271 literally blow up soon after it's been completed.

Big capacity turbochargers tend to suffer no power at low rpm, and small turbochargers spool up really quickly but don't have the top end bhp gains.

In the last 10 years the world of turbo chargers is always increasing and we are seeing variable vane turbo chargers, where the vane profile is altered according to speed to lower lag and increase top end power.

Twin scroll turbo chargers divert the exhaust gases into a couple of channels and push these at differently profiled vanes in the turbo charger. They also increase 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 and torque gains, although harder to setup. We have this in depth look at twinchargers if you want to read more.

Tips about fuel supply on the M271

You will need to ensure that the engine is not starved of fuel so must pay attention to the fuelling when you start extending past 20% of a bhp hike. Experienced tuners recommend to over specify your flow rate on the injectors.

The accepted safe increase is to add another 15% when fitting an injector, helps cope with injector deterioration and gives a bit of spare capacity should the engine need 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 M271 performance exhaust upgrades

We'd only recommend you look to boost your exhaust system with an upgraded one is if the current exhaust is actually causing a flow problem.

On most factory exhausts you'll find your flow rate is fine 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 can help equal out the flow of air through the engine.

But if the exhaust pipe is too big, ie: it's over two and a half inches diameter, you will lose much of the exhaust flow rate and end up lacking power and torque.

The usual suspects causing problems in your exhaust flow rate come around the filters installed, so adding a better flowing sports alternative will help avoid this restriction.

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

Faults issues and things to look out for on the M271

Like most engines an M271, 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 M271, failure to do this will exacerbate engine wear, on a tuned M271 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 M271 why not pop over to the forums at TorqueCars where you can chat about M271 tuning options and read about others projects who may be planning to do similar modifications on their M271.

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