BMW S50 Tuning

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

Dive into the world of high-performance engines with the BMW S50, a gem in the realm of automotive engineering. Originating from the esteemed M3 series, particularly the E36 M3, the S50 is a marvel of precision and power.

This inline-6 engine is not just a symbol of BMW's engineering prowess but also a favorite among car enthusiasts for its remarkable features and modification potential.

At the heart of the S50 engine is its advanced design, boasting a displacement ranging from 3.0 to 3.2 liters, depending on the variant.

This engine is renowned for its innovative features, such as individual throttle bodies and VANOS (Variable Valve Timing), which contribute to its responsive and dynamic performance. The S50's power output is impressive, delivering a thrilling driving experience straight from the factory.

What truly sets the S50 apart as an ideal project car engine is its blend of high base power and adaptability to modifications. Its solid and reliable build makes it a durable choice for enthusiasts looking to enhance their vehicle's performance.

The S50 is highly receptive to a range of modifications, from ECU tuning to enhance its performance parameters to exhaust system upgrades for a more aggressive sound.

The engine's popularity within the car community ensures an abundance of aftermarket parts and a rich reservoir of shared knowledge and experiences.

This makes the S50 not just a powerful engine, but a gateway to a customized, high-performance driving experience. Whether you are aiming for increased horsepower, torque, or a unique sound, the S50 engine stands as a robust and versatile foundation for your project car.

In this article we review and look at S50 tuning and report on the best modifications for your car.

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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.

Often parts chosen for the S52 highlight a suitable upgrade route, with the lower weight flywheel, better flowing exhaust headers, revised cam profile all point to areas BMW R&D team saw fit to improve.

S50 Camshaft Upgrades

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.

The Schrick 276/270 profiles make quite a difference, exceeding the S52 profile but you have to watch valve clearances on those and modify the Vanos travel by means of a shim or revised piston crown.

Camshaft upgrades on the BMW S50 engine are a significant step in enhancing its performance, especially when focusing on improving horsepower and torque across various RPM ranges. Like the S52, the S50 engine features BMW's VANOS system, a variable valve timing mechanism that optimizes engine performance and efficiency. Here's an overview of how camshaft upgrades can benefit the S50 engine:

Camshaft Upgrade Benefits:

Upgrading the camshafts in an S50 involves changing the cams to those with different profiles – usually with higher lift and longer duration.

These changes allow for more air and fuel to enter the combustion chamber and for exhaust gases to exit more efficiently, leading to increased power, particularly at higher RPMs.

The result is an engine that breathes better, providing enhanced throttle response and a more aggressive power curve.

Importance of VANOS with Camshaft Upgrades:

• The VANOS system in the S50 adjusts the timing of the valves based on engine speed and load. When upgrading camshafts, it's crucial to consider how these changes will interact with the VANOS system.
• Ideally, the upgraded camshafts should complement the VANOS, allowing for a broader range of efficient operation and maintaining drivability.

Valve Cutout Clearances and High Lift Cams:

One critical aspect of installing higher lift cams is ensuring proper valve cutout clearances. This refers to the space between the valves and the pistons, which is crucial to avoid contact between them, especially when the valves are opening further (higher lift).

Without adequate clearance, there's a risk of valve-to-piston contact, which can cause severe engine damage.

This may require modifications to the pistons or careful selection of camshaft profiles to ensure compatibility with the existing engine internals.

Considerations for Camshaft Upgrades:

It's not just a matter of installing new camshafts. These upgrades often require additional modifications, such as upgraded valve springs, retainers, and sometimes changes to the fuel and ignition systems.

A professional installation and tuning are crucial. The engine management system (DME or ECU) may need to be recalibrated to take full advantage of the new camshaft profiles.

The overall goal should be a balance between achieving higher performance and maintaining engine reliability and drivability.

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 we did find some Schrick cams for this engine though .
3. Remaps - S50 engine tuning/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 manifolds, drilled & smoothed airbox, Fast road camshaft, Remaps/piggy back ECU, Sports exhaust header/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).

DME Tunes/Remaps

The S50 power trains respond well to mods and thanks to their popularity there are increasing numbers of modifications and tuning parts about but the key to unlocking everything lies within the DME.

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

(In some cases, such as on the early S50's 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.)

Tuning the Digital Motor Electronics (DME), also known as the Engine Control Unit (ECU), is a popular way to enhance the performance of the BMW S50 engine. DME tuning involves adjusting the software that controls various engine functions to improve performance, efficiency, and sometimes even fuel economy. Here are the primary options for DME tuning on the S50:

Performance Chips:

For older models, like the early versions of the S50, a performance chip is often used. This is a physical chip that is installed into the DME, replacing or modifying the factory software.

These chips typically alter fuel maps, ignition timing, and sometimes remove limiters such as the top speed governor.

They are a cost-effective way to gain horsepower and torque, particularly in naturally aspirated setups.

Flash Tuning:

Flash tuning involves directly reprogramming the DME via its OBD (On-Board Diagnostics) port. This method is more common with newer versions of the S50 that have OBD-II ports (post-1996 models).

It offers more customization than a chip, as the software can be tailored to specific engine modifications like upgraded intakes, exhausts, or camshafts.

Flash tunes can be performed by a tuning specialist, either in person or remotely by sending your DME to them.

Custom Dyno Tuning:

Custom dyno tuning is the most personalized option. Here, the car is placed on a dynamometer, and the engine is tuned in real-time to optimize performance based on actual running conditions.

This approach is ideal for heavily modified engines or for achieving specific performance goals.

It's the most expensive option but offers the most precise and optimized tuning.

Aftermarket Standalone ECUs:

For those seeking the ultimate level of customization and control, a standalone ECU can replace the factory DME.

Brands like MoTeC, Haltech, and AEM offer ECUs that give tuners complete control over every engine parameter.

This option is typically used in high-performance builds or racing applications.

It will usually give you around 15% on NA (naturally aspirated) 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 manifolds 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

NA (naturally aspirated) 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.

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.

Lower compression pistons will help if you decide to go the forced induction route and are seeking higher power figures.

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.

Lighter Flywheels

Upgrading to a lighter flywheel on a BMW S50 engine, similar to the S52, can significantly enhance the driving experience, particularly in terms of engine responsiveness and acceleration. Here's an overview of how a lighter flywheel benefits the S50 engine:

1. Increased Engine Responsiveness: A lighter flywheel reduces the rotational inertia of the engine. This leads to quicker throttle response, allowing the engine to rev up and down more rapidly. This is particularly beneficial during quick acceleration and deceleration, making the engine feel more lively and responsive.
2. Quicker Acceleration: With less rotational mass, the engine doesn't have to work as hard to spin the flywheel. This results in more of the engine's power being used to drive the car, rather than just moving the flywheel. Consequently, drivers often notice improved acceleration times, as the engine can reach higher RPMs more swiftly.
3. Improved Driving Experience: The reduction in rotational mass offers a more direct connection between the throttle input and engine behavior. This results in a more engaging and enjoyable driving experience, especially in performance driving scenarios such as on a track.

However, there are some considerations to keep in mind:

• Risk of Engine Stall: The lower inertia of a lighter flywheel can make the engine more prone to stalling at low RPMs. This is especially noticeable in situations requiring precise throttle control, like in heavy traffic or starting from a standstill.
• Rougher Idle: The engine may experience a rougher idle due to the decreased ability to smooth out the pulses from the combustion process, a result of the reduced rotational mass.
• Loss of Low-End Torque Feel: In regular driving, particularly at lower speeds, the car might feel less smooth. The lighter flywheel removes some inertia that helps in maintaining engine momentum

Exhaust Upgrades on the  S50

You only need to increase your exhaust if your current exhaust is actually creating a restriction.

Exhaust upgrades are a popular modification for enhancing the performance of BMW engines, including the S50. These upgrades can range from replacing the headers (exhaust manifolds) to installing a full aftermarket exhaust system.

Here's how exhaust upgrades can impact the S50 engine and some specific considerations:

Headers Upgrade:

The S50 engine, particularly in North American models, came with more restrictive headers compared to the S52. Upgrading the S50 to a more free-flowing header design, like that found in the S52 or aftermarket versions, can significantly improve exhaust flow.

Improved headers help in reducing backpressure, allowing the engine to expel exhaust gases more efficiently. This leads to better breathing, which can enhance power, especially at higher RPMs.

Full Exhaust System Modifications:

Upgrading the entire exhaust system, including the mid-pipe, catalytic converters, and muffler, can further enhance performance.

These modifications typically aim to increase exhaust flow and velocity, improving the engine's overall efficiency and power output.

Importance of Exhaust Velocity:

It's not just about making the exhaust flow more freely; maintaining optimal exhaust velocity is crucial. Too large a diameter can decrease the velocity, potentially reducing low-end torque.

A well-designed exhaust system maintains a balance between flow and velocity, ensuring improvements across a broad RPM range.

Catalyst Removal Legalities:

• Removing or replacing catalytic converters can have legal and environmental implications. In many regions, it's illegal to remove catalytic converters due to emission control laws.
• Some areas permit better flowing sports cats, but this may still require you to meet emissions targets.
• When modifying the exhaust system, it's important to be aware of local emissions regulations and ensure that the vehicle remains compliant.

What to Expect from Exhaust Mods on the S50:

• Improved throttle response and a more aggressive exhaust note.
• Potential gains in horsepower and torque, particularly in the mid to high RPM range.
• Enhanced engine performance, especially when combined with other modifications like an upgraded intake system or ECU tuning.

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.

Crankshaft & High Compression Pistons.

Upgrading the BMW S50 engine with high compression pistons and a revised crankshaft is a significant step towards enhancing its performance, especially for those looking to maximize the engine's power output in naturally aspirated configurations.

High Compression Pistons:

• Installing high compression pistons increases the engine's compression ratio. This leads to more power and improved engine efficiency by extracting more energy from the combustion process.
• Higher compression usually results in a more responsive throttle and better power delivery, particularly noticeable in naturally aspirated engines like the S50.
• It's important to note that with increased compression, the engine may require higher octane fuel to prevent issues like knocking or pre-detonation.
• Along with the pistons, it's advisable to consider upgrading other internal components like the connecting rods, especially if the car will be used for performance driving or racing.

Revised Crankshaft:

• A revised crankshaft, often referred to as a stroker crank, can increase the displacement of the S50 engine. This is achieved by increasing the stroke length, which boosts the overall power and torque output.
• A stroker crankshaft not only increases engine displacement but can also improve the balance and smoothness of the engine.
• Upgraded crankshafts are generally made from stronger materials to withstand the increased stresses associated with higher power levels.

Considerations:

• These modifications require a comprehensive approach to engine tuning. They impact various engine dynamics, including air-fuel mixtures, ignition timing, and valvetrain operation.
• After these upgrades, recalibrating or reprogramming the DME (Digital Motor Electronics) or ECU (Engine Control Unit) is essential to accommodate the new engine dynamics.
• Typically, such upgrades are part of an extensive engine rebuild that might also include modifying the cylinder heads, camshafts, and the induction and exhaust systems for optimal performance.

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.

VANOS System Issues

The S50's VANOS (Variable Valve Timing) system can suffer from wear and tear over time. Common symptoms include a loss of power, rough idling, and a rattling noise from the front of the engine. In some cases, the VANOS may require rebuilding or replacement.

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

Cooling System Problems

BMW engines, including the S50, are known for cooling system issues. Problems such as failing water pumps, leaky radiators, and thermostat failures are not uncommon. Regular maintenance and inspection of the cooling system are crucial to prevent overheating and engine damage.

Keep an eye on your coolant system levels and investigate any unusual drops or discoloration.

Fuel Pump & Injector Issues

Fuel pump failures can lead to issues with fuel delivery, impacting both the performance and reliability of the engine. This often results in injector problems with this particular engine model. Therefore, it's essential to maintain proper fuel delivery to ensure optimal performance.

Symptoms of fuel pump failures include engine sputtering or stalling, difficulty starting the engine, decreased fuel efficiency, and noticeable loss of power while driving. Additionally, there may be unusual noises coming from the fuel tank area, such as whining or humming. It's important to address these symptoms promptly to avoid further damage to the engine and maintain safe driving conditions.

Oil Leaks

The S50 engine can develop oil leaks from several areas, including the valve cover gasket, oil filter housing gasket, and the oil pan gasket. Regular checks and timely replacement of these gaskets can prevent more significant problems.

Timing Chain Tensioner

The timing chain tensioner can become worn, leading to a noisy timing chain, especially on startup. If left unchecked, this could lead to more severe timing chain issues.

Worn Rod Bearings

Though not as prevalent as in the later S54 engine, the S50 can still experience rod bearing wear. This is particularly a concern for engines subjected to high-performance or track use. Regular oil changes and occasional bearing checks can help.

Mass Air Flow Sensor (MAF) Failure

The MAF sensor can become dirty or fail, leading to performance issues like hesitation, poor fuel economy, and difficulty starting the engine. Cleaning or replacing the MAF sensor can often resolve these issues.

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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