Modding upgrading and tuning the Mercedes M104 engine!

Car tuning tips:M104 Modifications"

M104 Modifications Guide

How to modify and upgrade the Mercedes M104

"Comprehensive guide to tuning the Mercedes M104 engine!"

TorqueCars are regularly getting messages about how to improve the M104 from people inquiring about getting more power from the M104 and wanting to know what are the premier M104 power upgrades. So let us look into Mercedes M104 parts and outline the best upgrades on this great engine and point out some problems along the way.

The Mercedes M104 provide a fun base for your project and with the optimum tuning modifications like ECU maps, turbo kits and camshafts you will substantially maximize your driving fun.

We shall review M104 tuning and point out the ultimate mods that work.

When talking about the greatest parts for your M104 engine, we are going to concentrate on the upgrades that give the biggest return for your cash.

M104 induction kits

Improving air intake on the M104

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 insufficient air it runs rich losing power which risks damage to the M104. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Getting air and fuel into your M104 is the main goal to any performance tuning task.

It is common that there's a restriction in the air flow sensor AFM/MAP on the M104 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 was restricting power at a much lower level.

Headers flow the on the suck phase from the intake filter and allow it to be sucked into the engine cylinders with fuel for the squish phase.

The shape and flow rate of the Headers can make a big improvement to fuel delivery on the M104.

Most intake manifold are ripe for a performance upgrade, although some OEM provide decently flowing intake manifold.

Adding a M104 larger valve kit, getting port work and head flowing will also improve bhp and torque, & importantly will permit increasing the bhp and torque increase on other parts.

M104 performance cam tips.

Different M104 engines respond better to different camshaft durations than others.

The engine timing and injectors and fuel pump also will make differences on the power gains you'll achieve.

Altering valve durations can alter the power 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 M104 camshaft will make a dramatic difference to the engine torque. Choosing a higher performance camshaft profile raises the torque accordingly.

NB: Fast road cams normally boost the bhp and torque throughout the rpm band, you could drop a little low end power but high end rpm power will be lifted.

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

On a daily driver you must carefully try to match your engines power to your preferences.

You will never have ever thought a M104 Motorsport camshaft is a pleasure to live with when driving in heavy traffic.

Stage 1, 2 and 3 mods for the M104

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 M104 parts:

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

Stage 2 M104 parts:

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

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

Stage 3 M104 parts:

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

Plan your options and then source your mods and set yourself a power target to avoid costly mistakes.

A remap should help to to establish the full potential of all the parts you've done to your M104.

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 differs on the parts you've fitted and the condition of your engine.

Turbo modifications on the M104

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 M104.

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 car is turbo charged parts are more reliable and you'll see that turbocharged engines already contain better components.

However every engines will have power limits

We recommend you find these limits and upgrade to better pistons and crank to cope with the power.

We've seen drivers spending a a stack of money on turbo upgrades on the M104 only to watch the car catastrophically fail soon after it's first rolling road session.

Large capacity turbo units often suffer low end lag, and small turbo units spool up more quickly but do not have the peak rpm torque gains.

Over the last 20 years the world of turbos is always increasing and we commonly find variable vane turbos, permitting the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbos divert the exhaust gases into a couple of channels and feed these at differently angled vanes in the turbo. They also help the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although more challenging to install. We have this in depth look at twinchargers if you want to read more.

Tips about fuel supply on the M104

You will need to ensure that the engine is not starved of fuel so should ramp up the fuelling when you start exceeding 20% of a torque hike. We strongly recommend you to be generous with your injectors flow rate.

The rule of thumb is to add 15% when fitting an injector, this takes into account injector deterioration and allows a bit of 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 M104 performance exhaust upgrades

We'd only recommend you look to upgrade your exhaust system with an upgraded one is if your current exhaust is actually creating a restriction in flow.

On most factory exhausts you'll see the flow rate is still 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 gases through the engine.

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

Usual exhaust restrictions come around the filters installed, so adding a higher flowing high performance alternative will help avoid this restriction.

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

Faults issues and things to look out for on the M104

Like most engines an M104, 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 M104, failure to do this will exacerbate engine wear, on a tuned M104 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 M104 why not pop over to the forums at TorqueCars where you can chat about M104 tuning options and read about others projects who may be planning to do similar modifications on their M104.

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