Tuning guide "OM608 Modifications"

OM608 Modifications Guide

How to modify and upgrade the Mercedes OM608

"Comprehensive guide to tuning the Mercedes OM608 engine!"

Sites like TorqueCars are regularly seeing threads requesting information on how to improve the OM608 from people wanting to know what are the best tips for OM608 upgrades. So let us look into Mercedes OM608 tuning mods and outline the best modifications on this great engine and point out some potential pitfalls along the way.

Now we will review OM608 tuning and show the best modifications. Mercedes OM608 are awesome to work on and with the best tuning enhancements like remapping, turbo kits and camshafts you will substantially increase your driving experience.

Just because particular modifications are popular with OM608 owners it doesn't mean you should fit it, we shall concentrate on the optimum modifications that will give your OM608 the best power gain for you money.

Without us subscribing to the misaprehension 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'.

OM608 induction kits

Improving air intake on the OM608

You need air and fuel for an engine to work. If there is not enough fuel then it will run lean, if there is insufficient air it runs rich losing 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 Forcing air into your OM608 is the main goal to any engine modification job.

It is not unusual that there's a limitation in the air flow sensor (AFM/MAF/MAP) on the OM608 when considerably more air is being pulled 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 performance at a much lower level.

Intake manifolds carry the air flow during the suck phase from the filter and allow it to be sucked into the engine cylinders with fuel for the squish phase.

Design and rate of flow of the Headers can make a big change to fuel atomisation on the OM608.

I usually find intake headers are in dire need of a performance upgrade, although a few manufacturers provide reasonably well designed intake headers.

Larger OM608 valves, doing a bit of OM608 port enlargement and head flowing will also improve torque, and importantly will permit increasing the torque increase on other parts.

OM608 performance cam tips.

Different OM608 engines even from the same production line will vary with some working better on different setups or needing less aggressive camshaft durations, but porting and flowing the head should reduce the differences and give consistent results.

The engine timing and fuelling also have a large bearing on the torque gains you'll achieve.

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.

Significant air intake, and exhaust improvements on the OM608 can be made from camshaft upgrades. Changing the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road cams commonly bump the performance across the rpm band, you may lose a little low end torque but your high end rpm power will be higher.

Race cams, 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 Competition cam won't do well if driving around busy urban areas.

You should ideally match your bhp range to your typical driving style so for a daily driver stick with a mild fast road OM608 cam

Stage 1, 2 and 3 mods for the OM608

Stage 1 OM608 parts:

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

Stage 2 OM608 parts:

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

Stage 3 OM608 parts:

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

The OM608 power trains make great tuning projects and thankfully there is a lot of parts and tuning parts about.
Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Remapping should help to to establish the full potential of all the modifications you've done to your OM608.

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 rely on the modifications you've applied and the condition of your engine.

Turbo modifications on the OM608

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 OM608.

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.

If the engine is fitted with a turbocharger upgrades are simpler to install and you will discover turbo charged engines will have uprated components.

There are tuning limits for every engine, with some being extremely strong and some only able to handle stock power

Research these restrictions and fit more solid crank and pistons to handle the power.

It's not unheard of tuners spending a a stack of money on turbo charger upgrades on the OM608 only to experience the car catastrophically fail when it's finished.

Larger turbo units will usually suffer a bottom end lag, and small turbo units spool up quickly but don't have the high rpm engines power gains.

We are pleased that the range of turbochargers is always developing and we are seeing variable vane turbochargers, where the vane angle is altered according to speed to lower lag and increase top end performance.

Twin scroll turbochargers divert the exhaust gases 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 bhp gains, although harder to install. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the OM608

Don't overlook the need to uprate the fuel delivery when you are increasing the bhp and torque - it makes the car more thirsty. Don't forget to be generous with your injector capacity.

The accepted safe increase is to add 15% to the flow rate when buying an injector, this accounts for injector deterioration and allows you 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 OM608 performance exhaust upgrades

You should look to increase your exhaust system with an upgraded one is if the current exhaust is actually creating a restriction in flow.

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

But if your exhaust pipe is too large, ie: it's over two and a half inches diameter, you will lose a lot of your flow rate and end up lacking power and torque.

The usual suspects causing problems in your exhaust flow rate can be traced to the 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 OM608

Like most engines an OM608, 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 OM608, failure to do this will exacerbate engine wear, on a tuned OM608 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 OM608 why not pop over to the forums at TorqueCars where you can chat about OM608 tuning options and read about others projects who may be planning to do similar modifications on their OM608.

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