Tuning the BMW M52

"Building the best modified BMW M52 engine!"

Carref prides itself on providing the latest tips and guides to your modification project.

The BMW M52 really good project engines and with carefully chosen sports parts like remaps, turbo improvements and camshafts you will really increase your driving fun.

TorqueCars will provide a guide to M52 tuning and report on the premier modifications for your car.

We rely on our visitors to pass on tips and tell us about their projects and what worked on their car, and this article is the culmination of the feedback we have received. First let us look at the history and specs of this engine and then consider which tuning modifications work best on it.

History of the Engine

• M52B20
• 110 kW (148 bhp) at 5900 rpm 190 N⋅m (140 lb⋅ft)  at 4200 rpm 1994-1998
• M52TUB20
• 110 kW (148 bhp)  at 5900 rpm 190 N⋅m (140 lb⋅ft) at 3500 rpm 1998-2000
• M52TUB24
• 135 kW (181 bhp)  at 5800 rpm 240 N⋅m (180 lb⋅ft)  at 3600 rpm 1998-2000
• M52B25
• 125 kW (168 bhp)  at 5500 rpm 245 N⋅m (181 lb⋅ft)  at 3950 rpm 1995-1998
• M52TUB25
• 125 kW (168 bhp) at 5500 rpm 245 N⋅m (181 lb⋅ft) at 3500 rpm 1998-2000
• M52B28
• 142 kW (190 bhp) at 5300 rpm 280 N⋅m (210 lb⋅ft) at 3950 rpm 1995-1998
• M52TUB28
• 142 kW (190 bhp) at 5500 rpm 280 N⋅m (210 lb⋅ft)  at 3500 rpm 1998-2000
• S52B32 
• 179 kW (240 bhp) at 6000 rpm 325 N⋅m (240 lb⋅ft) at 3800 rpm 1996- 2000

Tuning the BMW M52 and best M52 performance parts.

What are the most effective M52 upgrades

The best M52 mods on an engine are typically the ones that give the best power gain for you spend.

We won't be swayed by popular M52 mods, they need to be cost effective.

Altering your M52 camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

Fast road camshafts normally increase the power over the rev band, you could drop a little low end bhp but the higher rpm power will be lifted.

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

A Race camshaft makes it harder when on the daily commute.

You should ideally match your bhp range to your cars usage so for a road car stick with a fast road M52 camshaft

Each engine responds better to more aggressive cam durations check your engine on a rolling road.

The engine timing and fuel pump and injectors also will say much on the torque gains you'll hit.

Longer 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.

Modifying to STAGE 1:

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

Modifying to Stage 2:

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

Modifying to Stage 3:

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

Mapping will help release the full potential of all the upgrades you've done to your M52.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but power output often rely on the upgrades you've fitted and the condition of your engine.

It is the aim to any engine performance tuning project to force fuel and air into the M52 engine

The intake plenum transmit the air from the filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.

Structure and rate of flow of the Intake headers can make a big improvement to fuel atomisation and engine efficiency on the M52.

I usually find headers are improved through motorsport parts, although a few car makers provide reasonably well designed headers.

Adding a M52 larger valve kit, getting port work and head flowing will also lift torque, the fantastic side effect is it will permit a better torque increase on other upgrades.

Which turbo upgrades are best?

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 M52

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 an engine is fitted with a turbocharger parts are relatively easy and we find turbo charged engines will have harder and stronger components.

However engines will need better parts at higher power limits

We recommend you find these limitations and upgrade to higher quality crank and pistons to utilize the power.

We see many people spending a fortune on turbo charger upgrades on the M52 only to suffer the humiliation of seeing the car explode when it's been finished.

Larger turbo units commonly experience low end lag, and little turbo units spool up quickly but do not have the high rpm engines power gains.

Thankfully the market of turbo units is always moving on and we now see variable vane turbo units, where the vane angle is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbo units divert the exhaust gases into two channels and flow these at differently profiled vanes in the turbo charger. They also increase the scavenging effect of the engine.

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

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

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

Fuelling

You will need to ensure that the engine is not starved of fuel so will have to pay attention to the fuelling when you start extending past 20% of a performance increase.It makes sense to over specify your injectors flow rate.

As a rule of thumb add another 20% when fitting an injector, which takes into account injector deterioration and allows some spare capacity should the engine require 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.

Choosing the right performance exhaust

One of the most common mistakes and problems we see in tuning projects is usually down to the exhaust, or rather a poorly chosen exhaust for your engine.

You only need to to upgrade your exhaust if the current exhaust is creating a flow problem.

On most factory exhausts you'll see the flow rate is good even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Sports exhausts can help increase the flow of air through the engine.

But if your exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose much of the exhaust flow rate and end up losing power and torque.

Usual exhaust restrictions are traced to the filters installed, so adding a faster flowing sports alternative will help avoid this restriction.

Weak spots Issues & problem areas on the M52

The engines are generally reliable and solid as long as they are regularly serviced and maintained.

Regular oil changes are vital on the M52, especially when tuned and will help extend the life and reliability of the engine.

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

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which tuning mods work best for them on each model of car. Comments are used to improve the accuracy of these articles which are continually updated.

This article was written by Waynne Smith on TorqueCars, and I appreciate your feedback and suggestions. This entry was filed under BMW. You can leave a response below or join TorqueCars forum to discuss this article and car modification in detail with our members.

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