Modding tuning and best performance upgrades on the Mercedes M139 engine!

Car tuning tips:M139 Modifications"

M139 Modifications Guide

How to modify and upgrade the Mercedes M139

"Comprehensive guide to tuning the Mercedes M139 engine!"

Popular tuning sites like TorqueCars are regularly getting posts about how to improve the M139 from people wanting to know what are the things tuners recommend when it comes to M139 mods that work. So let us look into Mercedes M139 modifications and outline the best upgrades on this great engine and point out some common pitfalls along the way.

Now we will consider M139 tuning and point out the ultimate modifications. Mercedes M139 are awesome to work on and with the ultimate sports upgrades like remapping, turbo upgrades and camshafts you will definitely enhance your driving pleasure.

The optimum M139 mods on an engine are typically the ones that give the best gains for your money.

We won't be swayed by popular M139 mods, they need to be cost effective.

M139 induction kits

Improving air intake on the M139

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 too little air it runs rich resulting in lost power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Pulling air and fuel into your M139 is the aim to any engine modification job.

It is not unusual that there's a restriction in the air flow sensor AFM/MAF on the M139 when a lot more air is being pulled into the engine.

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

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

Shape and flow characteristics of the Intake headers can make a big difference to to fuel mixing and power on the M139.

It's not uncommon that intake headers are improved through aftermarket parts, although a few car makers provide decently flowing intake headers.

Increasing the M139 valve size, doing some M139 port enlargement and head flowing will also raise bhp and torque, this will raise potential for a greater bhp and torque increase on other parts.

M139 performance cam tips.

Some M139 engines respond better to more aggressive camshaft durations check your engine on a rolling road.

The map and injectors and fuel pump also have an effect on the torque gains you'll make.

Extending exhaust or intake 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.

Altering your M139 camshaft will make a dramatic difference to the engine power band. Choosing a higher performance camshaft profile raises the power band accordingly.

NB: Fast road camshafts normally boost the torque across the rev band, you may sacrifice a little low down power but the top end will be lifted.

Race camshafts, boost the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport and race cam will just annoy you whilst driving around busy urban areas.

You should ideally match your bhp range to your usage of the car so for a car used daily stick with a fast road M139 cam

Stage 1, 2 and 3 mods for the M139

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 M139 parts:

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

Stage 2 M139 parts:

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

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

Stage 3 M139 parts:

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

The M139 power trains respond well to upgrades and we're finding that there is a growing number of parts and performance parts about.

Remapping will help to establish the full potential of all the tuning parts you've done to your M139.

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 the end result often vary depending on the tuning parts you've applied and the condition of your engine.

Turbo modifications on the M139

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 M139.

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

When the engine is turbo charged parts are more reliable and you will discover turbo charged engines are built with strengthened components.

However every engines have weakspots

It is important to find these limitations and upgrade to higher quality crank and pistons to handle the power.

It's not unheard of tuners spending a lot of money on turbo charger upgrades on the M139 only to suffer the indignity of watching the M139 catastrophically fail when it's finished.

Larger capacity turbos tend to suffer low end lag, and smaller turbos spool up really quickly but don't have the peak rpm torque gains.

In the last 10 years the choice of turbo units is always evolving and we commonly find variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo units divert the exhaust gases into a couple of channels and push these at differently designed vanes in the turbocharger. 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 performance gains, although harder to install. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the M139

Don't miss you'll need to raise the fuel delivery when you are increasing the torque - it makes the car more thirsty. We would recommend you to over specify your injector capacity.

The rule of thumb is to add 20% to the flow rate when fitting an injector, which takes into account injector deterioration and provides 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 M139 performance exhaust upgrades

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

On most factory exhausts you'll see the flow rate is still 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 can help balance the flow of air through the engine.

But if your 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 losing power and torque.

Usual exhaust restrictions are traced to the emissions filters installed, so adding a freer flowing performance 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 M139

Like most engines an M139, 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 M139, failure to do this will exacerbate engine wear, on a tuned M139 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 M139 why not pop over to the forums at TorqueCars where you can chat about M139 tuning options and read about others projects who may be planning to do similar modifications on their M139.

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