BMW S50 Tuning

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

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.

History, Power & Specs of the Engine

S50B30

  • (Eu) 213 kW (286 hp) @7,000 rpm 319 Nm (235 lbft) @3,500 rpm

S50B30US

  • (USA) 179 kW (240 hp) @6,000 rpm 305 Nm (225 lbft) @4,250 rpm

S50B32

  • 239 kW (321 hp) @7,400 rpm 350 Nm (258 lbft) @3,250 rpm

Tuning the BMW S50 and best S50 performance parts.

Best S50B30 / S50B32 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.

Camshafts designed for the road tend to increase bhp and torque across the rpm range, although at the expense of a little of low-end bhp - around 270 seems a good compromise.

However, the vehicle will not idle smoothly and low-end power almost always suffers when using racing camshafts with a more aggressive profile.

While travelling through congested urban areas, a racing or motorsports cam will be an annoyance. There are several reasons why this is the case, but the most common one is that competitive cams have a very rough idle, which makes the vehicle more susceptible to stalling or jerking in stop-and-go traffic.

Make sure that the torque band matches your driving style by using a shorter-duration S50 cam for those who drive their cars every day

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.

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Best mods for your S50

  1. Flywheel lightening - a lower mass flywheel will improve the engines rev changes. But not always suitable for all S50 engines.
  2. Fast road Camshafts are significant power adders, but they must be installed by someone who knows what they are doing and they are not always easy to source but there might be a local firm to regrind a stock cam .
  3. Remaps - S50 remapping ensures the most advantage for the money, aftermarket ECUs, and piggyback ECUs are all alternatives.
  4. Upgrades to turbochargers and superchargers - Adding a turbocharger is the most significant way to raise the intake air supply, which permits you to burn more fuel and make power gains. It is one of the most technically difficult modifications you'll see massive gains.
  5. Flowing and porting the engine head - for larger gains, you will get better flow and make a more efficient engine if you do this to support your other mods.
  6. Intake and Sports Exhausts - Please note that on their own these mods will NOT ADD POWER in most cases, but they can help release power after other mods by losing a restriction.

S50 Tuning Stages

Typical stage 1 mods often include:
Panel air filters, Intake headers, drilled & smoothed airbox, Fast road camshaft, Remaps/piggy back ECU, Sports exhaust manifold.

Typical stage 2 mods often include:
induction kit, Fast road cam, high flow fuel injectors, fuel pump upgrades, Sports catalyst & performance exhaust, Ported and polished head.

Typical stage 3 mods often include:
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).

The S50 power trains respond well to mods and thanks to their popularity there are increasing numbers of modifications and tuning parts about.

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

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you 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 S50B30 / S50B32.

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.

Turbo upgrades for the S50B30 / S50B32

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 and the S50B30 / S50B32 are no exception with noted quality and power differences in the same production run, but thankfully not as bad as some manufacturers.

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.

S50 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.

Exhaust Upgrades on the  S50

You only need 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 catalyst removes the restriction. We note that performance cats perform similarly to decats and have the added benefit of keeping your car street legal, as decats or catalyst removal is illegal in most territories for road going cars.

Weak spots Issues & problem areas on the S50

These engines generally prove to be reliable and solid as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

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 .

If you would like to know more, or just get some friendly advice 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.

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