Modifying and tuning the BMW B58

Tuning guide "BMW B58 Tuning"

BMW B58 Tuning Guide

"Modifying the BMW B58 engine!"

Now we will outline options for your B58 tuning and show the ultimate modifications. BMW B58 are popular engines and with the right mods like a remap, turbo kits and camshafts you will substantially improve your driving enjoyment.

When talking about the optimum parts for your B58 engine, we are going to concentrate on the tuning mods that give the best power gain for you money.

Altering your B58 camshaft will make a dramatic difference to the engine torque. Choosing a higher performance camshaft profile raises the torque accordingly.

NB: Fast road camshafts usually increase the bhp and torque over the rpm band, you may lose a little bottom end bhp but the high end rpm power will be higher.

Competition camshafts, increase the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport camshaft won't do well if driving in heavy traffic.

You should ideally optimize your power band to your driving style so for a daily driver stick with a shorter duration B58 camshaft

Some B58 engines respond better to different camshaft durations so view each engine as unique.

The map and injectors and fuel pump also have an effect on the power gains you'll get.

Extending exhaust or intake durations can alter the power 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.

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

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

Stage 3 mods: Engine balancing & blueprinting, Twin charging conversions, Competition cam, Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves).The B58 power trains respond well to mods and we note that there is a lot of mods and performance parts about.

Mapping helps unlock the full potential of all the parts you've done to your B58.

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 often differs on the parts you've done and the condition of your engine.

It is the main goal to any engine tuning task to shove more fuel and air into each cylinder

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

The bore size, shape and flow characteristics of the Intake can make a noticeable improvement to fuel atomisation on the B58.

I usually find plenum chambers are ripe for performance upgrades, although a few OEM provide fairly well optimized plenum chambers.

Fitting big valve kits, carrying out 3 or 5 angle valve jobs and porting and head flowing will also improve power, this will raise potential for a better power increase on other mods.

B58 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 B58

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

If your motor is turbo charged parts are relatively easy and turbocharged engines are made with better components.However engines have limits

See where you'll find these limits and upgrade to better quality crank and pistons to cope with the power.

It's not unheard of car owners spending a lot of money on turbocharger upgrades on the B58 only to see the whole thing literally blow up when it's completed.

Large capacity turbo units commonly experience low end lag, and low capacity turbo units spool up really quickly but don't have the peak end engines power gains.

Thankfully the market of turbos is always increasing and we are seeing variable vane turbos, where the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbos divert the exhaust flow into a couple of channels and push these at differently designed vanes in the turbocharger. They also help the scavenging effect of the engine.

You'll commonly see there is a limitation in the air flow sensor (AFM/MAF/MAP) on the B58 when considerably more air is being drawn into the engine.

When tuning you may well find you need to get an air sensor or flow meter capable of upto 4 bars to cope 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 power gains, although more challenging to setup. We have this in depth look at twinchargers if you want to read more.

Fuelling upgrades and B58 engine mods

When you increase the bhp and torque you will need to look at to the fuel system.

More bhp and torque needs more fuel. It makes sense to over specify your injectors flow rate.

The rule of thumb is to add 20% when buying an injector, this takes into account injector deterioration and allows you 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..

B58 Exhaust upgrades and mods

You should look to replace your exhaust if the existing exhaust is actually causing a restriction in flow.

On most factory exhausts you'll see your 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.Do not go with the biggest exhaust you can source this will slow up the exhaust flow rate - the best exhausts 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 can be traced to the catalyst and filters installed, so adding a faster flowing sports alternative will help avoid this restriction.

B58 weakspots, Issues & common problems

The B58 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the B58, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your B58 engine please join us in our friendly forum where you can discuss tuning options in more detail with our B58 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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