Modding uprating the Mercedes M178 engine!

Tuning guide "M178 Modifications"

How to modify and upgrade the Mercedes M178

"Comprehensive guide to tuning the Mercedes M178 engine!"

Popular tuning sites like TorqueCars are regularly getting messages requesting information on how to improve the M178 from people inquiring about getting more power from the M178 and wanting to know what are the ultimate M178 mods that work. So let us look into Mercedes M178 parts and outline the best modifications on this great engine and point out some common pitfalls along the way.

Therefore we detail the best approach to M178 tuning and report on the greatest upgrades. Mercedes M178 provide a fun base for your project and with a few sensible modified enhancements like ECU maps, turbo improvements and camshafts you will certainly improve your driving enjoyment.

When talking about the ultimate parts for your M178 engine, we are going to concentrate on the mods that give the biggest return for your cash.

M178 induction kits

Improving air intake on the M178

You need air and fuel 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 and potentially damaging the engine. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the aim to any car tuning project to push air and fuel into each cylinder but this has a knock on effect with the air flow sensor.

You'll commonly see there is a limit in the air flow sensor MAF/MAP on the M178 when loads more air is being sucked into the engine.

When tuning you may well find you need to get an air sensor or flow meter capable of upto 4 bars to cope with quite large power gains, whereas the OEM air sensor sapped bhp at a much lower level.

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

Design and rate of flow of the air Intake manifold can make a big difference to to fuel delivery on the M178.

We often see headers are in dire need of aftermarket tuning parts, although a few OEM provide reasonably good headers.

Adding a M178 larger valve kit, doing some M178 port enlargement and head flowing will also lift performance, this will afford you a better performance increase on other tuning mods.

M178 performance cam tips.

Some M178 engines respond better to different camshaft durations check your engine on a rolling road.

The map and fuelling also will say much 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 M178 cam will make a dramatic difference to the engine torque. Choosing a higher performance cam profile raises the torque accordingly.

NB: Fast road cams usually bump the bhp and torque across the rpm range, you may lose a little low down power but the higher rpm power will be higher.

Race cams, 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 makes it harder when driving in heavy traffic.

You should ideally optimize your bhp range to your usage of the car so for a typical daily driver stick with a shorter duration M178 cam

Stage 1, 2 and 3 mods for the M178

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 M178 parts:

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

Stage 2 M178 parts:

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

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

Stage 3 M178 parts:

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

Review your options and then find your upgrades and set yourself a power target to save yourself from expensive mistakes.

Mapping helps fully realize the full potential of all the modifications you've done to your M178.

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 differs on the modifications you've carried out and the condition of your engine.

Turbo modifications on the M178

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 M178.

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.

When a car is turbocharged, tuning parts are giving better power gains and you'll see that turbocharged engines are built with harder and stronger components.

There are common areas of failure for every engine, with some being over specified and some only able to handle stock power

We recommend you find these restrictions and fit higher quality components to survive the power.

We see many mechanics spending a loads of money on turbocharger upgrades on the M178 only to suffer the indignity of watching the car literally blow up just after it's used in anger.

Large capacity turbo units tend to suffer low end lag, and little turbo units spool up quickly but don't have the high rpm engines power gains.

Thanks to progress the world of turbo chargers is always improving and we are seeing variable vane turbo chargers, permitting the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo chargers divert the exhaust flow into two channels and flow these at differently profiled vanes in the turbo charger. 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 setup. We have this guide to twinchargers if you want to read more.

Tips about fuel supply on the M178

You will need to ensure that the engine is not starved of fuel so should increase the fuelling when you start going beyond 20% of a power hike. Care modifiers usually say to be generous with your injectors flow rate.

The rule of thumb is to add 20% to the flow rate when buying an injector, which takes into account injector deterioration and allows 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 M178 performance exhaust upgrades

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

On most factory exhausts you'll see your flow rate is still 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 will certainly help air flow out of the engine but do not go too large or you could will reduce the flow rate. Stick to one and a half to two and half inches for best results.

The usual suspects causing problems in your exhaust flow rate are traced to the catalyst installed, so adding a freer flowing high performance 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 M178

Like most engines an M178, 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 M178, failure to do this will exacerbate engine wear, on a tuned M178 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 M178 why not pop over to the forums at TorqueCars where you can chat about M178 tuning options and read about others projects who may be planning to do similar modifications on their M178.

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