Modding tuning and best performance upgrades on the BMW S52 engine!

Tuners tips on "S52 Modifications"

S52 Modifications Guide

How to modify and upgrade the BMW S52

"Comprehensive guide to tuning the BMW S52 engine!"

TorqueCars are frequently getting emails asking about how to improve the S52 from people inquiring about getting more power from the S52 and wanting to know what are the best tips on S52 modifications. So let us look into BMW S52 upgrades and outline the best modifications on this great engine and point out some common pitfalls along the way.

We shall review and look at S52 tuning and highlight the best mods that work. BMW S52 make awesome project engines and with the right modified upgrades like a remap, turbo improvements and camshafts you will noticeably enhance your driving pleasure.

Just because particular parts are are common on S52 it doesn't mean you should fit it, so we'll concentrate on the best parts that will give your S52 the biggest power gain return for your cash.

Without us subscribing to the misaprehension of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

S52 induction kits

Improving air intake on the S52

You need fuel and air for an engine to work. If there is little supply of fuel then it will run lean, if there is a lack of air it runs rich losing power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Forcing more fuel and air into each cylinder is the whole point to any car tuning project.

It is not unusual that there's a restriction in the air flow sensor MAP/MAF/AFM on the S52 when a lot more air is being pulled into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting torque at a much lower level.

Intake take the during the engines suck phase from the air cleaner and allow it to be drawn into the engine cylinders.

Structure and flow characteristics of the Headers can make a large improvement to fuel atomisation and engine efficiency on the S52.

It's not uncommon that plenum chambers are needing a performance upgrade, although a few car makers provide reasonably good plenum chambers.

Big valve conversions on the S52, carrying out port matching and head flowing will also raise torque, and importantly will give you a greater torque increase on other tuning mods.

S52 performance cam tips.

Each engine responds better to more or less aggressive camshaft durations check your engine on a rolling road.

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

A longer valve duration 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.

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 power band gains are on offer for camshaft upgrades.

NB: Fast road cams usually boost the torque through the rev range, you might lose a little low down power but your higher rpm power will improve.

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

A Race cam won't do well if in heavy traffic.

You should ideally optimize your engines power to your driving style so for a road car stick with a mild fast road S52 cam

Stage 1, 2 and 3 mods for the S52

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 S52 parts:

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

Stage 2 S52 parts:

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

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Stage 3 S52 parts:

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

The S52 power plant are fantastic to work on and we're finding that there are quite a few choices of parts and performance parts out there.

Mapping will help fully realize the full potential of all the tuning parts you've done to your S52.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the end result will vary depending on the tuning parts you've applied and the condition of your engine.

Turbo modifications on the S52

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the S52.

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

When a car has a turbocharger upgrades are more reliable and most turbo charged engines use better components.

There are practical limits for every engine, with some being incredibly solid and some only just able to handle stock power

We recommend you find these restrictions and upgrade to better quality crank and pistons to handle the power.

We've seen mechanics spending a a stack of money on turbocharger upgrades on the S52 only to watch the whole thing throw a rod soon after it's finished.

Bigger upgraded turbos tend to suffer no power at low rpm, and smaller turbos spool up much more quickly but won't have the top end engines power gains.

In recent times the world of turbochargers is always improving and we are seeing variable vane turbochargers, where the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbochargers divert the exhaust flow into 2 channels and direct these at differently angled vanes in the turbo charger. They also help the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large torque gains, although more challenging to get working. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the S52

You will need to ensure that the engine is not starved of fuel so must look at the fuelling when you start going beyond 20% of a bhp hike. We would recommend you to over specify your injector capacity.

The accepted safe increase is to add 20% capacity when specifying an injector, helps cope with injector deterioration and affords some spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended S52 performance exhaust upgrades

You should look to uprate your exhaust system with an upgraded one is if the current exhaust is actually causing a restriction.

On most factory exhausts you should find that the exhaust flow rate is ok even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Note that with the largest exhaust you can get you'll slow up the exhaust flow rate - the best for power gains are usually between one and a half to two and half inches. Your exhaust design, the bend angles and construction are what have more effect on flow rates than your pipe width to a certain extent. So the exhaust design is a big factor.

Usual exhaust restrictions are in the emissions filters installed, so adding a faster flowing performance alternative will help avoid this restriction.

Catalyst removal (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the S52

Like most engines an S52, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the S52, failure to do this will exacerbate engine wear, on a tuned S52 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your S52 why not pop over to the forums at TorqueCars where you can chat about S52 tuning options and read about others projects who may be planning to do similar modifications on their S52.

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