Tuning the Mercedes M152

"Comprehensive guide to performance parts and tuning the Mercedes M152 engine!"

We often are getting messages inquiring about getting more power from the M152 and wanting to know what are the best M152 upgrades. So let us look into Mercedes M152 modifications and outline the best upgrades on this great engine and point out some frequent tuning mistakes along the way.

Our aim here is to consider M152 tuning and outline the best modifications. Mercedes M152 really good project engines and with carefully picked uprated parts like remaps, turbo kits and camshafts you will certainly enhance your driving enjoyment.

When talking about the best parts for your M152 engine, we are going to concentrate on the parts that give the best power gain for you spend.

Significant gains on the M152 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

NB: Fast road camshafts tend to raise the power across the rev band, you could sacrifice a little low down power but higher rpm power will be better.

Motorsport and race camshafts, raise the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a typical daily driver you need to match your torque band to your typical driving style.

I'd be amazed if you find a M152 Motorsport and race cam is a pleasure to live with when driving around busy urban areas.

Some M152 engines respond better to more or less aggressive camshaft durations check your engine on a rolling road.

The engine timing and injectors and fuel pump also have a large bearing on the torque gains you'll make.

Altering valve 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.

M152 Tuning Stages

Stage 1 M152 modifications: Sports exhaust manifold, Panel air filters, Drilled & smoothed airbox, Remaps/piggy back ECU, Intake headers, Fast road camshaft.

Stage 2 M152 modifications: fuel pump upgrades, Ported and polished head, Sports catalyst & performance exhaust, Fast road cam, induction kit, high flow fuel injectors.

Stage 3 M152 modifications: Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Twin charging conversions, Competition cam, Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger).

ECU flashing will help fully realize the full potential of all the mods you've done to your M152.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results may vary depending on the mods you've done and the condition of your engine.

Feeding air and fuel into each cylinder is the main goal to any engine performance tuning job.

Headers take the air during the suck phase from the air cleaner and allow it to be sucked into the engine cylinders with fuel for the squish phase.

The size of bore and shape and rate of flow of the Plenum can make a big difference to to fuel atomisation and engine efficiency on the M152.

Commonly we find the intake manifold are needing motorsport parts, although a few OEM provide well optimised intake manifold.

Big valve conversions on the M152, doing some port work and head flowing will also improve torque, & more importantly will make space for increasing the torque increase on other modifications.

Turbo upgrades for the M152

NASP engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your M152

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 your motor has a turbocharger parts are more reliable and turbocharged engines already contain many forged and stronger components.

There are weak spots for every engine, with some being over specified and some just sufficiently able to handle stock power

See where you'll find these restrictions and install more solid crank and pistons to handle the power.

We've seen drivers spending a loads of money on turbo upgrades on the M152 only to experience the engine literally blow up soon after it's finished.

Bigger upgraded turbo chargers often suffer low end lag, and little turbo chargers spool up quickly but do not have the top end power band gains.

We are pleased that the selection of turbochargers is always increasing and we now see variable vane turbochargers, permitting the vane angle is altered according to speed to lower lag and increase top end performance.

Twin scroll turbochargers divert the exhaust gases into 2 channels and direct these at differently angled vanes in the turbo charger. They also boost the scavenging effect of the engine.

It is not unusual that there is a restriction in the air flow sensor MAF/MAP on the M152 when a lot more air is being drawn into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited bhp at a much lower level.

Adding a supercharger or additional turbo will make large torque gains, although more challenging to configure. We have this in depth look at twinchargers if you want to read more.

Uprating M152 fuel injectors

You will need to ensure that the engine is not starved of fuel so will have to look at the fuelling when you start exceeding 20% of a power increase.It is important to over specify your injectors flow rate.

As a rule of thumb add 20% to the flow rate when fitting an injector, this accounts for injector deterioration and gives a little spare capacity should the engine need more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

Best M152 performance exhausts

You should look to uprate your exhaust if the current exhaust is actually creating a restriction.

On most factory exhausts you should find that your flow rate is still fine even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Do not go with the biggest exhaust you can source you'll slow the exhaust rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Typically exhaust restrictions can be traced to the catalyst and filters installed, so adding a freer flowing high performance alternative will help avoid this restriction.

Problems and issues to look out for on the M152

The M152 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M152, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M152 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M152 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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We really like hearing from our readers, and hearing about which tuning mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our M152 guides and tips are kept up to date.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Mercedes. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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