Modding uprating the Mercedes M273 engine!

Tuning guide "M273 Modifications"

M273 Modifications Guide

How to modify and upgrade the Mercedes M273

"Comprehensive guide to tuning the Mercedes M273 engine!"

Sites like TorqueCars often are getting emails requesting info on how to improve the M273 from people wanting to know what are the things tuners recommend when it comes to M273 modifications. So let us look into Mercedes M273 parts and outline the best upgrades on this great engine and point out some potential pitfalls along the way.

The Mercedes M273 are good project engines and with carefully picked modifications like remapping, turbo improvements and camshafts you will enhance your driving pleasure.

Here we review and look at M273 tuning and highlight the greatest upgrades.

Just because particular modifications are appear in lots of M273 projects it doesn't mean you should fit it, instead we will focus on the top modifications that will give your M273 the best value for money to power increase.

Without us subscribing to the 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'.

M273 induction kits

Improving air intake on the M273

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

So Pulling more air into the M273 engine is the main goal to any engine performance tuning task.

It is not unusual that there is a limit in the air flow sensor AFM/MAP on the M273 when a lot more air is being drawn into the engine.

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp at a much lower level.

Headers transmit the on the suck phase from the filter and allow it to be sucked into the engine cylinders.

The size of bore and shape and rate of flow of the Intake can make a large improvement to fuel engine efficiency on the M273.

Many mass produced engine plenum chambers are in dire need of motorsport parts, although a few makers provide reasonably well designed plenum chambers.

Adding a M273 larger valve kit, doing some port work and head flowing will also lift bhp, and significantly will allow you to get an improved bhp increase on other parts.

M273 performance cam tips.

Different M273 engines respond better to more or less aggressive cam durations than others.

The ecu map and fuelling also will make differences on the torque gains you'll achieve.

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.

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 usually increase the bhp and torque through the rpm band, you may lose a little low end torque but the top end will be higher.

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

On a daily driver you should ideally to match your engines power to your usage of the car.

You'll never have found a M273 Motorsport camshaft is a pleasure to live with when driving around busy urban areas.

Stage 1, 2 and 3 mods for the M273

Stage 1 M273 parts:

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

Stage 2 M273 parts:

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

Stage 3 M273 parts:

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

The M273 engine blocks are fantastic to work on and thanks to their popularity there is a growing number of upgrades and performance parts out there.

ECU mapping helps release the full potential of all the mods you've done to your M273.

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 usually rely on the mods you've applied and the condition of your engine.

Turbo modifications on the M273

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 M273.

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

When your car is fitted with a turbocharger tuning parts are more reliable and you will discover turbocharged engines are built with harder and stronger components.

However you'll find engines will have power limits

See where you'll find these restrictions and fit better quality components to handle the power.

It's not unheard of people spending a lot of money on turbo upgrades on the M273 only to have the M273 explode just after it's completed.

Big capacity turbo chargers often experience a bottom end lag, and smaller turbo chargers spool up much more quickly but don't have the high rpm torque gains.

Thanks to new tech the market of turbochargers is always developing and we commonly find variable vane turbochargers, allowing the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust gases into 2 channels and feed these at differently profiled 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 and torque gains, although more challenging to configure. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the M273

You will need to ensure that the engine is not starved of fuel so should uprate the fuelling when you start exceeding 20% of a power hike. At this point we flag up the need to be generous with your injectors flow rate.

The accepted safe increase is to add 20% capacity when buying an injector, this takes into account injector deterioration and provides you some 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 M273 performance exhaust upgrades

We'd only recommend you look to improve your exhaust system with an upgraded one is if the existing exhaust is creating a restriction in flow.

On most factory exhausts you'll find the flow rate is good 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 balance the flow of air through the engine.

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

The usual suspects causing problems in your exhaust flow rate can be located the catalyst and filters installed, so adding a better flowing sports 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 M273

Like most engines an M273, 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 M273, failure to do this will exacerbate engine wear, on a tuned M273 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 M273 why not pop over to the forums at TorqueCars where you can chat about M273 tuning options and read about others projects who may be planning to do similar modifications on their M273.

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