Modified M48 tuning guide

All you need to know about "BMW B48 Tuning"

BMW B48 Tuning Guide

"Modifying the BMW B48 engine!"

This pages aim is review and look at B48 tuning and show the best modifications. BMW B48 are popular tuning projects and with the ultimate uprated enhancements like remapping, turbo improvements and camshafts you will noticeably maximise your driving fun.

Just because particular mods are popular with B48 owners it doesn't mean its worth having, instead we will best mods that will give your B48 the best power gain for you money.

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 engines power gains are on offer for cam upgrades.

NB: Fast road cams normally increase the bhp and torque throughout the rpm band, you could drop a little low down power but the higher rpm power will improve.

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

A Motorsport camshaft is not great on the daily commute.

You should ideally match your engines power to your cars usage so for a road car stick with a shorter duration B48 camshaft

Some B48 engines respond better to extreme camshaft durations so set your engine up on a rolling road.

The ecu map and injectors and fuel pump also have an effect on the bhp gains you'll achieve.

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.

Our top 7 top upgrades for your motor, and we will break these into stages and discuss them in detail for you.

  1. Map Tunes - remapping, via either OBD port, or piggyback ECU's and aftermarket ECU's can all make decent gains
  2. Fuelling Pump Injectors - You'll need to match the greater air flow with more fuel to unlock the power
  3. Turbo upgrades - Improving the intake charge with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex especially where conversions are required).
  4. Suspension Upgrades - always improve your cars handling, tuning is not just about engine mods
  5. Brake Upgrades - Even before adding power improve your cars brakes to effectively stop the car
  6. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  7. Exhaust - as with intakes it helps to remove a restriction in the exhaust, cats are the usual bottleneck

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

Stage 1 mods: Drilled & smoothed airbox, Panel air filters, Sports exhaust manifold, Remaps/piggy back ECU, Fast road camshaft, Intake headers.

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

Stage 3 mods: Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Twin charging conversions, Competition cam, Internal engine upgrades (head flowing porting/bigger valves).The B48 power trains respond well to upgrades and we see that there are quite a few choices of modifications and tuning parts out there.

Mapping will help release the full potential of all the modifications you've done to your B48.

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 usually vary depending on the modifications you've carried out and the condition of your engine.

It is the aim to any engine modification job to pull air and fuel into your B48

The intake plenum transmit the air from the intake filter and allow it to be sucked into the engine cylinders with fuel for the squish phase.

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

Structure and rate of flow of the Intake headers can make a noticeable effect on to fuel mixing and power on the B48.

Most intake are crying out for motorsport parts, although some manufacturers provide reasonably well designed intake.

Fitting big valve kits, getting port work and head flowing will also lift power, this will afford you an improved power increase on other upgrades.

Turbo upgrades

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 a separate 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 B48

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 your motor has a turbo already fitted modifications are giving better power gains and turbo engines are made using strengthened components.However every engines will need better parts at higher power limits

It is important to find these restrictions and install higher quality components to survive the power.

We've seen guys spending a loads of money on turbocharger upgrades on the B48 only to suffer the indignity of watching the motor go up in smoke just after it's finished.

Bigger upgraded turbo units commonly suffer a bottom end lag, and little turbo units spool up much more quickly but don't have the peak rpm bhp gains.

In recent times the selection of turbo units is always evolving and we now see variable vane turbo units, where the vane angle is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo units divert the exhaust flow into 2 channels and feed these at differently profiled vanes in the turbocharger. They also help the scavenging effect of the engine.

It is not unusual that there's a limitation in the air flow sensor AFM/MAF on the B48 when a lot more air is being drawn into the engine.

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped torque at a much lower level.Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large performance gains, although more difficult to setup. We have this article covering twinchargers if you want to read more.

Fuelling upgrades and mods

You will need to ensure that the engine is not starved of fuel so must ramp up the fuelling when you start exceeding 20% of a bhp increase.

Don't forget to over specify your flow rate on the injectors.

The accepted safe increase is to add another 20% when buying an injector, which takes into account injector deterioration and gives you some spare capacity should the engine require 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..

Exhaust upgrades and mods

You only need to to boost your exhaust if your current exhaust is actually causing a flow problem.

On most factory exhausts you'll see the flow rate is still good even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.Don't go with the largest exhaust you can buy this will 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.

The usual suspects causing problems in your exhaust flow rate can be located the catalysts installed, so adding a higher flowing performance alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the B48

The B48 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the B48, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your B48 engine please join us in our friendly forum where you can discuss tuning options in more detail with our B48 owners. It would also be worth reading our unbiased 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 really like hearing from our readers, and hearing about which upgrades were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our B48 guides and tips are kept up to date.

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