Tuning the BMW B38

"All you need to know about tuning and performance parts on the BMW B38 engine!"

Carref prides itself on providing the latest tips and guides to your modification project.

Herein we detail the best approach to B38 tuning and show the greatest modifications for your car.

The B38 is a 3 cylinder turbo petrol engine, which replace the N13 in 2013.

We review and look at B38 tuning and show the premier modifications.

The weight of the engine makes the power feel all the more present, and the turbos can be tweaked to produce more power.

BMW B38 make a good tuning project and with the optimum sports modifications like remapping, turbo improvements and camshafts you will positively increase your driving fun.

We rely on our visitors to pass on tips and tell us about their projects and what worked on their car, and this article is the culmination of the feedback we have received. First let us look at the history and specs of this engine and then consider which tuning modifications work best on it.

History of the Engine

B38: 3 cylinder turbocharged petrol engine.

The weight of the engine makes the power feel all the more present, and the turbos can be tweaked to produce more power.

B38A12U0

• 55 kW (74 bhp) at 4,000 rpm 150 N⋅m (111 lb⋅ft) at 1,400–4,000 rpm
• 75 kW (101 bhp) at 4,250 rpm 180 N⋅m (133 lb⋅ft) at 1,400–4,000 rpm

2014–current F55/F56 Mini One First
2014–2018 F55/F56 Mini One

B38A15M0

• 75 kW (101 bhp) at 4,250 rpm 180 N⋅m (133 lb⋅ft) at 1,400–4,000 rpm
• 100 kW (134 bhp) at 4,400–6,000 rpm 220 N⋅m (162 lb⋅ft) at 1,250–4,300 rpm

2015– BMW F45/F46 216i Active Tourer / Gran Tourer
2018– F55/F56 Mini One
2015– BMW F20/F21 116i
2015– BMW F20/F21  118i
2015– BMW F22/F23 218i coupe / convertible
2014– BMW F45/F46 218i Active Tourer / Gran Tourer
2015–2019 BMW F30/F31 318i
2015– BMW F48 X1 sDrive18i
2014– F55/F56/F57 Mini Cooper
2015–2019 F54 Mini Clubman
2017– F60 Mini Countryman
2017– F39 X2 sDrive18i
2017– F45 225xe Active Tourer (PHEV)
2019– F40 118i
2019– F44 218i Gran Coupé

B38K15T0

• 170 kW (228 bhp) at 5,800 rpm 320 N⋅m (236 lb⋅ft) at 3,700 rpm

2013– BMW I12 i8

Tuning the BMW B38 and best B38 performance parts.

What are the most effective B38 tuning mods

The top B38 upgrades on an engine are typically the ones that give the best power gain for you spend.

We won't be swayed by popular B38 upgrades, they need to be cost effective.

Altering your B38 cam will make a dramatic difference to the engine engines power. Choosing a higher performance cam profile raises the engines power accordingly.

Fast road camshafts usually boost the torque across the rev range, you may lose a little low down torque but the high end rpm power will be better.

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

A Competition cam is not great on the daily commute.

You should ideally optimize your torque band to your driving style so for a typical daily driver stick with a fast road B38 cam

Some B38 engines respond better to mild cam durations so view each engine as unique.

The ecu map and fuel pump and injectors also have a large bearing on the torque gains you'll achieve.

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.

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Modifying to Stage 1:

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

Modifying to Stage 2:

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

Modifying to Stage 3:

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

Remaps helps release the full potential of all the tuning parts you've done to your B38.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage may rely on the tuning parts you've fitted and the condition of your engine.

Pushing air and fuel into the B38 engine is the aim to any tuning task.

The intake plenum transmit the air from the intake filter and allow it to be sucked into the engine cylinders.

The size of bore and shape and flow rate of the Headers can make a substantial change to fuel delivery on the B38.

On popular production engines plenum chambers are begging for aftermarket parts, although some car makers provide reasonably well designed plenum chambers.

Increasing the B38 valve size, getting port work and head flowing will also boost performance, and more importantly will raise potential for a better performance increase on other tuning parts.

Which turbo upgrades are best?

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 B38

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.

If an engine is fitted with a turbo parts are going to net you a larger power gain and most turbocharged engines are made using more solid components.

There are weak spots for every engine, with some being very over engineered and some just sufficiently able to handle stock power

See where you'll find these restrictions and install better pistons and crank to survive the power.

We see many mechanics spending a lots of money on turbo upgrades on the B38 only to have the engine throw a rod just after it's used in anger.

Big upgraded turbos tend to experience a bottom end lag, and little turbos spool up quickly but don't have the peak end torque gains.

In recent times the choice of turbochargers is always moving on and we commonly find variable vane turbochargers, where the vane angle is altered according to speed to lower lag and increase top end torque.

Twin scroll turbochargers divert the exhaust gases into two channels and push these at differently profiled vanes in the turbo charger. They also improve the scavenging effect of the engine.

It is common that there's a limitation in the air flow sensor AFM/MAF on these engines when considerably 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 bhp and torque at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more difficult to get working. We have this in depth look at twinchargers if you want to read more.

Fuelling

You will need to ensure that the engine is not starved of fuel so need to look at the fuelling when you start extending past 20% of a torque increase.When it comes to your injectors capacity and flow rate you need some spare capacity, so don't calculate which injector and fuel pump setup will match your needs exactly or you'll have flat spots and fuelling issues and problems.

The accepted safe increase is to add another 20% when fitting an injector, this allows for injector deterioration and affords a little spare capacity should the engine need 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.

B38 Exhaust

You only need to to upgrade your exhaust if your exhaust is actually creating a flow problem.

On most factory exhausts you'll see your flow rate is still ok 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 from the engine but do not go too big or you could will reduce the flow rate. Stick to 1.5 to 2.5 inches for best results.

Usual exhaust restrictions can be located the catalysts installed, so adding a better flowing race alternative will help avoid this restriction.

Weak spots Issues & problem areas on the B38

The B38 engines are generally reliable and solid as long as they are regularly serviced and maintained.

Regular oil changes are vital on the B38, especially when tuned and will help extend the life and reliability of the engine.

For more information on Tuning your B38 engine please join us in our friendly forum where you can discuss tuning options in more detail with our 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 love to hear what our visitors have got up to and which tuning mods work best for them on each model of car. Comments are used to improve the accuracy of these B38 articles which are continually updated.

This article was written by Waynne Smith on TorqueCars, and I appreciate your feedback and suggestions. This entry was filed under BMW. You can leave a response below or join TorqueCars forum to discuss this article and car modification in detail with our members.

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