Tuning the BMW B58

"Comprehensive guide to tuning the BMW B58 engine!"

The BMW B58 are awesome to work on and with carefully picked performance enhancements like remapping, turbo improvements and camshafts you will positively maximise your driving opportunities.

Our aim here is to detail the best approach to B58 tuning and summarise the best mods that work.

The greatest B58 mods on an engine are obviously the ones that give the best power gain for you spend.

We won't be swayed by popular B58 mods, they need to be cost effective. We actually have a more frequently updated article on our .com site about B58 Tuning.

Significant gains on the B58 can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road camshafts commonly push up the performance throughout the rpm band, you may lose a little low end power but higher rpm power will improve.

Race camshafts, push up the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

On a car driven daily one should, ideally, try to optimize your power band to your cars usage.

I'd be gobsmaked if you have ever thought a B58 Race camshaft is a pleasure to live with when driving around busy urban areas.

Different B58 engines respond better to different cam durations than others.

The ECU mapping and injectors and fuel pump also will say much on the torque gains you'll hit.

Altering valve durations 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.

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

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

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

Carefully think through your options and then acquire your upgrades and set yourself a power target to avoid wasting your time and money.

ECU flashing helps to establish the full potential of all the upgrades you've fitted to your B58.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the end result usually rely on the upgrades you've carried out and the condition of your engine.

Feeding more fuel and air into your B58 is the aim to any car tuning project.

Air Intake manifolds flow the air during the suck phase from the air cleaner and allow it to be sucked into the engine and mixed with fuel.

The shape and flow characteristics of the Air Intake manifolds can make a large improvement to fuel delivery on the B58.

I usually find headers are needing an upgrade, although some makers provide reasonably good headers.

Larger B58 valves, getting port work and head flowing will also raise bhp, the fantastic side effect is it will allow you to get a greater bhp increase on other modifications.

Turbo upgrades

NASP 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 B58

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.

If the engine has a turbo already fitted tuning mods are simpler to install and you will discover turbocharged engines use many forged and stronger components.

However engines will need better parts at higher power limits

We recommend you find these limitations and upgrade to more solid crank and pistons to survive the power.

We see many people spending a a stack of money on turbo upgrades on the B58 only to see the car literally blow up soon after it's been completed.

Large capacity turbo chargers commonly experience no power at low rpm, and small turbo chargers spool up quickly but don't have the peak rpm bhp gains.

We are pleased that the world of turbo units is always increasing and we now see variable vane turbo units, where the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbo units divert the exhaust flow into 2 channels and push these at differently angled vanes in the turbo. They also improve the scavenging effect of the engine.

It is not unusual that there is a limit in the air flow sensor AFM/MAP on the B58 when a lot 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 bhp and torque at a much lower level.

Adding a supercharger or additional turbo will make large power gains, although harder to setup. We have this article on twincharging 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 look at the fuelling when you start going beyond 20% of a bhp increase.It is important to over specify your flow rate on the injectors.

As a rule of thumb add 20% to the flow rate when buying an injector, which takes into account injector deterioration and affords some 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.

Exhaust upgrades and mods

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

On most factory exhausts you should find that the flow rate is fine even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Sports exhausts can usually air flow out of the engine but avoid an exhaust that is too large or you could will reduce the flow rate. Stick to 1.5 to 2.5 inches as a rule of thumb.

Typically exhaust restrictions are in the catalyst and filters installed, so adding a freer flowing performance alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the B58

The B58 engines are extremely reliable and solid as long as they are regularly serviced and maintained.

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.

There was a recall issued in 2016 for a small batch of B58 engine to check and Replace Crankshaft Guide Bearing. It is known to wear prematurely, and you'll get a warning light on rather than a catastrophic and costly engine failure.

 

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

We need your help improving this article, so please send us your feedback in the comments box below and pass on any tips, points or facts we have wrong or have not covered.

We really like hearing from our readers, and hearing about which mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our guides and tips are kept up to date.

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