Modding tuning and best performance upgrades on the Mercedes OM654 engine!

Tuning guide "OM654 Modifications"

OM654 Modifications Guide

How to modify and upgrade the Mercedes OM654

"Comprehensive guide to performance parts and tuning the Mercedes OM654 engine!"

Forums like the one at TorqueCars often are getting emails requesting info on how to improve the OM654 from people wanting to know what are the best OM654 power upgrades. So let us look into Mercedes OM654 modifications and outline the best mods that work on this great engine and point out some potential pitfalls along the way.

Car Tuning Tips will review OM654 tuning and highlight the optimum modifications for your car. Mercedes OM654 provide a fun base for your project and with a few sensible tuning mods like ECU maps, turbo kits and camshafts you will positively enhance your driving fun.

Just because particular upgrades are appear in lots of OM654 projects it doesn't mean you should fit it, we will concentrate on the top upgrades that will give your OM654 the best value for money to power increase.

Without us subscribing to the popular myth 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'.

OM654 induction kits

Improving air intake on the OM654

You need fuel and air for an engine to work. If there is not enough fuel then it will run lean, if there is too little air it runs rich resulting in lost power which risks damage to the OM654. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So it's important to any engine tuning task to force air into the OM654 engine but this has a knock on effect with the air flow sensor.

It is common that there is a limit in the air flow sensor AFM/MAF on the OM654 when loads more air is being sucked into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp and torque at a much lower level.

Engines intake headers flow the on the suck phase from the intake filter and allow it to be drawn into the engine and mixed with fuel.

Design and flow characteristics of the Intake headers can make a big change to fuel engine efficiency on the OM654.

Many mass produced engine intake headers are in dire need of performance upgrades, although some car makers provide fairly well optimized intake headers.

Increasing the OM654 valve size, carrying out OM654 port enlargement and head flowing will also improve bhp and torque, & more importantly will allow you to get an improved bhp and torque increase on other mods.

OM654 performance cam tips.

Different OM654 engines respond better to more or less aggressive cam durations check your engine on a rolling road.

The map and injectors and fuel pump also have a large bearing on the torque gains you'll achieve.

A longer valve duration 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 torque gains are on offer for cam upgrades.

NB: Fast road camshafts commonly bump the bhp and torque throughout the rev range, you could sacrifice a little low down power but the high end rpm power will be lifted.

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

A Motorsport and race camshaft will just annoy you whilst in heavy traffic.

You should ideally optimize your power band to your typical driving style so for a daily driver stick with a mild fast road OM654 camshaft

Stage 1, 2 and 3 mods for the OM654

Stage 1 OM654 parts:

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

Stage 2 OM654 parts:

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

Stage 3 OM654 parts:

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

The OM654 engines are great to work on and we're pleased to see that there is a lot of modifications and tuning parts around.
Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Remaps helps release the full potential of all the tuning parts you've done to your OM654.

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 may depend much on the tuning parts you've fitted and the condition of your engine.

Turbo modifications on the OM654

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 OM654.

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.

If a car is fitted with a turbocharger modifications are more reliable and we find turbocharged engines use more solid components.

However every engines will have power limits

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

It's not unheard of drivers spending a a stack of money on turbocharger upgrades on the OM654 only to have the engine explode on it's first outing after it's been finished.

Big turbos tend to experience a bottom end lag, and smaller turbos spool up quickly but won't have the peak end bhp gains.

In the last 10 years the range of turbo units is always developing and we are seeing variable vane turbo units, permitting the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbo units divert the exhaust flow into two channels and direct these at differently designed 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 performance gains, although harder to install. We have this in depth look at twinchargers if you want to read more.

Tips about fuel supply on the OM654

You will need to ensure that the engine is not starved of fuel so need to increase the fuelling when you start exceeding 20% of a bhp and torque hike. We would recommend you to be generous with your injector capacity.

The rule of thumb is to add 20% capacity when fitting an injector, this accounts for injector deterioration and gives you some 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 OM654 performance exhaust upgrades

You only need to to replace your exhaust system with an upgraded one is if your exhaust is actually causing a restriction.

On most factory exhausts you'll see the 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 can usually 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 as a rule of thumb.

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

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

Faults issues and things to look out for on the OM654

Like most engines an OM654, 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 OM654, failure to do this will exacerbate engine wear, on a tuned OM654 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 OM654 why not pop over to the forums at TorqueCars where you can chat about OM654 tuning options and read about others projects who may be planning to do similar modifications on their OM654.

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