Tuning the BMW S50

"All you need to know about tuning and performance parts on the BMW S50 engine!"

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

The BMW S50 are awesome to work on and with the right tuning parts like ECU maps, turbo improvements and camshafts you will greatly improve your driving pleasure.

In this article we review and look at S50 tuning and report on the best 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

• M50B20 110 kW (148 hp) @6,000 rpm 190 N⋅m (140 lbft) @4,700 rpm
• M50B20TU 110 kW (148 hp) @5,900 rpm 190 N⋅m (140 lbft) @4,200 rpm
• M50B24TU 138 kW (185 hp) @5,900 rpm 240 N⋅m (177 lbft) @4,200 rpm
• M50B25 141 kW (189 hp) @6,000 rpm 245 N⋅m (181 lbft) @4,700 rpm
• M50B25TU 141 kW (189 hp) @5,900 rpm 250 N⋅m (184 lbft) @4,200 rpm
• S50B30
  (Eu) 213 kW (286 hp) @7,000 rpm 319 N⋅m (235 lbft) @3,500 rpm
• S50B30US (USA) 179 kW (240 hp) @6,000 rpm 305 N⋅m (225 lbft) @4,250 rpm
• S50B32 239 kW (321 hp) @7,400 rpm 350 N⋅m (258 lbft) @3,250 rpm

Tuning the BMW S50 and best S50 performance parts.

What are the most effective S50 tuning mods

When talking about the best greatest for your S50 engine, we are going to concentrate on the tuning mods that give the best value for money.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen camshaft profile, so large torque gains are on offer for camshaft upgrades.

Fast road camshafts tend to bump the bhp and torque across the rpm range, you might lose a little low end bhp but the top end will be better.

Motorsport camshafts, bump 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 driving around busy urban areas.

You should ideally optimize your torque band to your driving style so for a car driven daily stick with a shorter duration S50 cam

Each engine responds better to mild cam durations than others.

The ECU mapping and injectors and fuel pump also have an effect 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.

Modifying to STAGE 1:

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

Modifying to Stage 2:

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

Modifying to Stage 3:

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

A remap should help to unlock the full potential of all the upgrades you've done to your S50.

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

Feeding air and fuel into your S50 is the aim to any tuning project.

Intake manifold transmit the air during the suck phase from the intake filter and allow it to be fed into the engine cylinders with fuel for the squish phase.

The bore size, shape and flow rate of the Intake manifold can make a noticeable change to fuel delivery on the S50.

I usually find headers are in desperate need of aftermarket parts, although a few manufacturers provide decently flowing headers.

Adding a S50 larger valve kit, doing a bit of S50 port enlargement and head flowing will also raise performance, and importantly will allow you to get a greater performance increase on other tuning parts.

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 S50

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.

When your car is turbo charged mods are relatively easy and you'll see that turbocharged engines are built using many forged and stronger components.

However most engines have weakspots

See where you'll find these limits and upgrade to better quality crank and pistons to survive the power.

It's not unheard of car owners spending a loads on turbo upgrades on the S50 only to suffer the humiliation of seeing the whole thing literally blow up just after it's been enthusiastically driven.

Large upgraded turbo units will usually experience low end lag, and small turbo units spool up more quickly but do not have the peak end torque gains.

Thanks to progress the selection of turbo chargers is always moving on and we are seeing variable vane turbo chargers, permitting the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo chargers divert the exhaust gases into 2 channels and push these at differently designed vanes in the turbocharger. They also improve the scavenging effect of the engine.

It is common that there's a restriction in the air flow sensor AFM/MAF on the when considerably more air is being drawn into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped performance at a much lower level.

Adding a supercharger or additional turbo will make large bhp gains, although more challenging to install. We have this article covering twinchargers if you want to read more.

Fuelling

Don't miss you'll need to increase the fuel system when you are increasing the performance - it makes the car more thirsty. We strongly recommend you to be generous with your flow rate on the injectors.

The accepted safe increase is to add 20% to the flow rate when specifying an injector, this accounts for injector deterioration and affords 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.

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 increase your exhaust if your current exhaust is actually creating a restriction.

On most factory exhausts you should find that your flow rate is still ok 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 balance the flow of gases through the engine.

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

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

Weak spots Issues & problem areas on the S50

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

Regular oil changes are vital on the s50, especially when tuned and will help extend the life and reliability of the engine.

Check for Vanos issues, rumbles and rough idle, the Vanos components should be replaced every 150000 miles .

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 s50 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 modifications 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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