BMW S52 Tuning

"All you need to know about tuning the BMW S52 engine!"

TorqueCars will consider S52 tuning and outline the optimum upgrades. BMW S52 are awesome to work on and with the ultimate uprated tuning mods like ECU maps, turbo improvements and camshafts you will positively improve your driving enjoyment.

The straight-6 DOHC petrol engine S52 is one of BMW's finest ever creations. E36 M3 from 1996–1999.. able to respond to adjustments. It has a huge following in the aftermarket. If you like, the S52 is also a good candidate for forced induction. An iron block and solid bottom end can handle a lot of boost.

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History, Power & Specs of the Engine

The S52 is a highly tuned variant of the M52 and ran from 1996-2000

The cast iron block of the M50 was, in most areas, replaced with an aluminium block with iron sleeves, this allowed the engine displacement to increase from 2.5 to 2.8 Liters.

The engine has a larger bore and stroke giving a 10.5:1 compression ratio. It also had camshafts mods with more lift and duration.

  • 240 hp (179 kW) at 6,000 rpm and 236 lbft (320 Nm) of torque at 3,800 rpm

Tuning the BMW S52 and best S52 performance parts.

Best S52 upgrades

When talking about the best best for your S52 engine, we are going to concentrate on the ones that give the best power gain for you spend.

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

Fast road cams tend to boost the bhp and torque across the rpm range, you might lose a little bottom end torque but your top end will be higher.

Competition cams, boost the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a daily driver you need to optimize your power band to your cars usage.

I'd be shocked if you have ever thought or claimed that a S52 Competition cam is a pleasure to live with when driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

Different S52 engines respond better to extreme cam durations check your engine on a rolling road.

The engine timing and fuelling also will make differences on the torque gains you'll get.

A longer valve duration 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.

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Best mods for your S52

  1. Flowing and porting the Head - Head work will get air flowing into the engine while removing turbulence or restrictions.
  2. Fast road Camshafts are are often the best upgrade for an engine, but they must be fitted by someone who knows what they are doing and you might struggle to find one but there might be a local firm to regrind a stock camshaft .
  3. Remaps - A tune/remap ensures the biggest gains in terms of cost, replacement ECUs, and piggyback ECUs are all alternatives.
  4. Turbo upgrades - forced induction is the most efficient approach to improve intake air supply, allowing you to use more fuel and make higher power. It is one of the most challenging mods it offers big gains.
  5. Air Induction and Exhaust - Note that on their own these mods won't ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  6. Lighter flywheels - a lighter flywheel will improve the engines rev changes. But not always suitable for all S52 engines.

S52 Tuning Stages

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

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

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

Carefully think through your options and then acquire your tuning parts and set yourself a power target to save yourself from expensive mistakes.

ECU mapping should help to release the full potential of all the tuning parts you've fitted to your S52.

(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 NA (naturally aspirated) engines, but the end result may rely on the tuning parts you've fitted and the condition of your engine.

It is vital to any engine tuning task to shove more fuel and air into each cylinder

Air Intake manifolds transmit the air from the filter and allow it to be drawn into the engine and mixed with fuel.

The size of bore and shape and flow characteristics of the Intake manifolds can make a noticeable effect on to fuel mixing and power on the S52.

We often see air intake manifolds are ripe for motorsport parts, although a few car makers provide well optimised air intake manifolds.

Fitting big valve kits, carrying out S52 port enlargement and head flowing will also increase torque, and more importantly will afford you raising the torque increase on other parts.

S52 Turbo upgrades

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 S52 but we would caution against it, you'd be practically rebuilding the entire block.

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes superb power gains.

In the last 10 years the selection of turbochargers is always evolving and we are seeing variable vane turbochargers, permitting the vane profile is altered according to speed to lower lag and increase top end power.

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

It is common that there's a limit in the air flow sensor AFM/MAF on the when considerably more air is being sucked 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 performance gains, although more difficult to install. We have this guide to twinchargers if you want to read more.

S52 Fuelling Upgrades

When you boost the torque you will need to pay attention to the fuel delivery.

More torque needs more fuel.

Most tuners we speak with say 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 allows a bit of 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.

S52 Performance Exhaust Upgrades

You may need to replace your exhaust if the current exhaust is actually creating a restriction.

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.

Note that with the biggest exhaust you can buy you'll slow up the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Usual exhaust restrictions can be traced to the filters installed, so adding a higher flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

S52 Weak Spots Issues & problem areas on the S52

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.

The Lambda sensor's readings are skewed when there are air leaks in the intake manifold. The S52 engine is prone to this and it is quite well documented but can cause lumpy running, poor idling and misfires.

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

Keep a watch on the VANOS and replace it if it begins acting up after 10 years of ordinary driving. This is a regular issue with such a complicated system. So at high mileages it is recommended to change the Double Vanos and Lambda sensor.

Thermostat housing can start to leak coolant.

High oil consumption may be due to worn piston rings where oil seeps into the cylinders.

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