The Lowdown on "OM611 Modifications"

How to modify and upgrade the Mercedes OM611

"Comprehensive guide to performance tuning the Mercedes OM611 engine!"

Forums like the one at TorqueCars are frequently getting messages asking how to improve the OM611 from people inquiring about getting more power from the OM611 and wanting to know what are the greatest OM611 upgrades. So let us look into Mercedes OM611 parts and outline the best upgrades on this great engine and point out some potential pitfalls along the way.

Now we will review and look at OM611 tuning and outline the greatest mods that work. Mercedes OM611 make awesome project engines and with carefully chosen modified mods like remaps, turbo kits and camshafts you will dramatically improve your driving enjoyment.

Just because particular upgrades are are common on OM611 it doesn't mean it is good, so we'll focus on the best upgrades that will give your OM611 the best power gain for you spend.

Without us subscribing to the popular 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'.

Improving air intake on the OM611

You need air and fuel for an engine to work. If there is insufficient fuel then it will run lean, if there is not enough air it runs rich resulting in lost 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 Feeding fuel and air into each cylinder is the main goal to any engine modification job.

You'll commonly see there's a limitation in the air flow sensor AFM/MAP on the OM611 when considerably more air is being fed 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.

The intake plenum carry the air from the filter and allow it to be sucked into the engine and mixed with fuel.

The bore size, shape and flow characteristics of the Plenum can make a big difference to to fuel delivery on the OM611.

It's not uncommon that intake are in dire need of motorsport parts, although some car makers provide reasonably good intake.

Fitting big valve kits, doing some port work and head flowing will also improve torque, & more importantly will raise potential for a greater torque increase on other tuning mods.

OM611 performance cam tips.

Some OM611 engines respond better to extreme cam durations than others.

The ECU mapping and fuel pump and injectors also will make differences on the bhp gains you'll hit.

Altering valve durations can alter the bhp 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.

Significant air intake, and exhaust improvements on the OM611 can be made from camshaft upgrades. Changing the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

NB: Fast road cams usually raise the power over the rev band, you could sacrifice a little bottom end torque but top end will be better.

Race cams, raise 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 on the daily commute.

You should ideally optimize your bhp range to your typical driving style so for a car driven daily stick with a shorter duration OM611 cam

Stage 1, 2 and 3 mods for the OM611

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 OM611 parts:

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

Stage 2 OM611 parts:

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

Stage 3 OM611 parts:

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

ECU flashing will help unlock the full potential of all the mods you've done to your OM611.

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 figures achieved usually vary depending on the mods you've carried out and the condition of your engine.

Turbo modifications on the OM611

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 OM611.

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 your car has a turbocharger tuning parts are going to make more power and most turbo engines are made using harder and stronger components.

However you will find an engines will have power limits

We recommend you find these limitations and fit higher quality components to handle the power.

We see many drivers spending a loads of money on turbo upgrades on the OM611 only to have the car catastrophically fail when it's completed.

Larger capacity turbos will usually suffer a bottom end lag, and low capacity turbos spool up quickly but do not have the top end engines power gains.

Over the last 20 years the range of turbochargers is always moving on and we commonly find variable vane turbochargers, where the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust flow into a couple of channels and push these at differently designed 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 difficult to setup. We have this article on twincharging if you want to read more.

Tips about fuel supply on the OM611

When you increase the torque you will need to uprate to the fuel delivery.

More torque needs more fuel. It makes sense to be generous with your flow rate on the injectors.

The rule of thumb is to add 15% when buying an injector, this takes into account injector deterioration and provides a little 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 OM611 performance exhaust upgrades

The only time you should look to upgrade your exhaust system with an upgraded one is if the existing exhaust is actually creating a restriction in flow.

On most factory exhausts you should find that the exhaust flow rate is 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 will certainly help air flow out of the engine but avoid an exhaust that is too wide 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 are in the catalyst and filters installed, so adding a freer flowing high 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 OM611

Like most engines an OM611, 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 OM611, failure to do this will exacerbate engine wear, on a tuned OM611 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 OM611 why not pop over to the forums at TorqueCars where you can chat about OM611 tuning options and read about others projects who may be planning to do similar modifications on their OM611.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We want to know your experiences with tuning parts on your OM611, it helps us improve our tips and keeps us current so please use the comments box to drop a tip.

This entry was posted under Makes and Models. Tags: engine, mercedes
You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Check out TorqueCars new YouTube channel, and see their awesome new content...