BMW 4 Series Tuning (F32,F33 & F36)

"Thank you for reading my BMW 4 Series tuning article."

We look into 4 Series tuning and provide tips on the optimum modifications. BMW 4 Series make awesome project cars and with the ultimate enhancements, you can dramatically enhance your driving enjoyment.

The 4 Series is a good car modification project to carry out. If you do your planning then you can create an awesome 4 Series but don't be fooled there are lots of tuning modifications out there that will simply not suit it read our unbiased guides first.

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Turning our attention to the engine we need to get a bit more torque out of the top end.

All turbo and especially diesel engines are crying out for a remap, you'll hit 30% more power with the right map/engine setup and should also get improve fuel economy.

BMW really have made an awesome car in the 4 Series, it looks stunning, performs well and ticks most boxes for even the most discerning driver.

4 Series Engine tuning mods.

These are the sports kits are usually installed by our members, decide how far you want to push your car before you get going.

• 418i 2016– B38A15M0
  1.5 L turbocharged I3 100kw (134hp) @4,400–6,000rpm 220 Nm (162lbft) @1,250–4,300rpm
• 420i 2014–2016 N20B20
  2.0 L turbocharged i4 135kw (181hp) @5,000–6,250rpm 270 Nm (199lbft) @1,250–4,500rpm
  2016– B48B20A
  2.0 L turbocharged i4 135kw (181hp) @5,000–6,500rpm 270 Nm (199lbft) @1,350–4,600rpm
• 428i 2013–2016 N20B20
  2.0 L turbo i4 180kw (241hp) @5,000–6,000rpm 350 Nm (258lbft) @1,250–4,800rpm
• 430i 2016– B48B20B
  2.0 L turbocharged i4 185kw (248hp) @5,250–6,500rpm 350 Nm (258lbft) @1,450–4,800rpm
• 435i 2013–2016 N55B30M0 (twin scroll turbo)
  3.0 L turbocharged I6 225kw (302hp) @5,800–6,500rpm 400 Nm (295lbft) @1,200–5,000rpm
• 440i 2016– B58B30M0
  3.0 L turbocharged I6 240kw (322hp) @5,500–6,500rpm 450 Nm (332lbft) @1,380–5,000rpm
• M4 2013– S55B30T0
  3.0 L twin-turbocharged I6 317kw (425hp) @5,600–7,300rpm 550 Nm (406lbft) @1,800–5,500rpm
• M4 Comp 2016– 331kw (444hp) @7,000rpm
• M4 CS 2017– 338kw (453hp) @6,250–7,000rpm 600 Nm (443lbft) @4,000–5,380rpm
• M4 GTS 2016– 368kw (493hp) @6,250rpm 600 Nm (443lbft) @4,000–5,000rpm

Diesel engines

• 418d 2014–2015 N47D20
  2.0 L turbocharged i4 105kw (141hp) @4,000rpm 300 Nm (221lbft) @1,750–3,000rpm
  2015– B47D20
  2.0 L turbocharged i4 110kw (148hp) @4,000rpm 320 Nm (236lbft) @1,500–3,000rpm
• 420d 2013–2015 N47D20
  2.0 L turbocharged i4 135kw (181hp) @4,000rpm 380 Nm (280lbft) @1,750–2,750rpm
  2015– B47D20
  2.0 L turbocharged i4 140kw (188hp) @4,000rpm 400 Nm (295lbft) @1,750–2,500rpm
• 425d 2014–2016 N47D20O1
  2.0 L twin-turbocharged i4 160kw (215hp) @4,400rpm 450 Nm (332lbft) @1,500–2,500rpm
  2016– B47D20O1
  2.0 L twin-turbocharged i4 165kw (221hp) @4,400rpm 450 Nm (332lbft) @1,500–3,000rpm
• 430d 2014– N57D30O1
  3.0 L turbocharged I6 190kw (255hp) @4,000rpm 560 Nm (413lbft) @2,000–2,750rpm
• 435d xDrive 2014– N57D30T1
  3.0 L twin-turbocharged I6 230kw (308hp) @4,400rpm 630 Nm (465lbft) @1,500–2,500rpm

Getting the right sports modifications for your planned usage of the car is vital. Stage 3 (competition) mods just don't work well on the road and will make the car undrivable.

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Best mods for your 4 Series

1. Forced induction upgrades - forced induction is the most significant way to increase air supply, ensuring you are able to combust more fuel and make better power figures. Typically one of the most technically difficult upgrades you'll see massive gains.
2. ECU Tunes - 4 Series engine tuning/remapping ensures the biggest gains compared to your outlay, aftermarket ECU upgrades, and piggyback ECUs are all alternatives.
3. Lighter flywheels - a reduced weight flywheel will significantly improve the engines rev changes. Not always a great mod for all 4 Series engines.
4. Fast road cams are significant power adders, but we strongly suggest they be fitted by someone competent and some cams are hard to find but there might be a local firm to regrind a stock cam .
5. Braking Mods - Enhancing your stopping power needs to be somewhere in your mods list.
6. Air Induction and Exhaust - Note that on their own these mods won't ADD POWER in most cases, but they enable you to enhance power after other mods by minimizing the restriction.
7. Flowing and porting the Head - Head work will get air flowing into the engine while removing turbulence or restrictions.
8. 4 Series Suspension Upgrades - Replacing worn bushings and shocks radically improves your 4 Series handling Adjustable coilovers and better bushings are what is needed here.

4 Series Tuning Stages

Typical stage 1 mods often include: Panel air filter, Sports exhaust, Engine Tunes/Remapping, Suspension upgrade (drop 26mm - 43 mm.), Lighter flywheel, Alloy wheels, intercooler.

Typical stage 2 mods often include: Ported and polished head, high flow fuel injector, Fast road cam, Power/Sport clutch, fuel pump upgrades.

Typical stage 3 mods often include: Sports gearbox, Competition cam, Internal engine upgrades (pistons/head/valves), Engine balancing, Adding or upgrading forced induction (turbo/supercharger).

You need to keep as much low end power as possible and aim to get a wide power band rather than a narrow top end power hike.

The point of our tips is to give a limited introduction of modifying performance parts and point you in the right direction, our forum is the place to go for detailed advice and tips on your car tuning project, the best uprated kits and all aspects of modding cars.A fast road cam usually proves to be one of the best NASP power mods you can do with a single part fitted to your engine.

The intake and exhaust durations play a huge factor in your cars power band, but be careful here, getting this wrong can upset the idle and make the car challenging to drive in traffic. You'd need to follow a camshaft upgrade with other mods and finish with a reflashed ECU for the best performance gains.

You will need to ensure that the engine is not starved of fuel so will need to ramp up the fuelling.

If you find you suffer from flat spots and power surges after your motorsport mods you should check the fuelling and try a higher octane fuel as well. To get sufficient fuel you may need to upgrade the injectors on your engine.

Uprate the fuel pump to cope with the extra fuel requirements of your tuned 4 Series's uprated injectors.

4 Series Handling/Suspension upgrades

Many 4 Series owners uprate the handling of their cars with tuning suspension mods as a priority, this will certainly increase your enjoyment of the car.

Good suspension tweaks that substantially benefit handling for the 4 Series include a couple of degrees negative camber and 1-1.5 degrees of toe in or out on the front wheels. Toe in for stability, or Toe out to improve cornering.

Drop the car optimally somewhere in the region of 26mm - 43 mm. and fit motorsport grade stiffer dampers, bigger drops will need other modifications in most instances.

Coilovers make good sense, especially if you have a wide range of adjustment on them, and can set the ride height to suit your preferences. The H&R spring lowering kit for the 4 series is very well designed and put together.

The coilovers from BC racing offer around 30 settings, and are probably the best value 4 series upgrade out there. Look also to the KW Varient 3's and we've even seen some air suspension kits already appearing, notably the one from airrex but we've not been a fan of air suspension from a performance point of view, but offers a range of aesthetically pleasing settings, so it will suit those more into the look of the car.

Upgrading your Bushes

Enhancements to the bushings: Things you need to know

Bushes, which are rubber mounts, allow the 4 Series's suspension components to be fixed to the car's chassis. The rubber ones will lose their shape with time.

New OEM rubber bushes may have a major impact on the performance of your vehicle.

Because the polyurethane bushes are firmer, the ride may be a bit bumpier, but they will last longer and maintain the handling.

Increased vibration and play may also quicken the stress in other suspension parts.

A new set of polyeyurothane bushings may be able to minimize the excessive play that comes with rubber bushes.

4 Series Brake Upgrades

It would also pay to improve the brakes, by adding larger discs and or higher friction pads.

Brake upgrades make sense, with many upgrading non M series models to the M series brakes. The 370mm front discs make a big difference over the smaller OEM originals. It's worth noting that many models have the same 4 pot calipers as the M sport, but come with 340mm discs but you'll still need to swap the calipers to carry the length difference.

Fitting meatier brake discs and better high performance brake pads will make for greatly improved braking.

We should point out that race brake pads can grind and will need a lot of heat before they bite.

In every day driving the brakes are only applied now and then so will not stop you as well so source brake pads which work well in daily use.

4 Series Intake and Exhaust Tuning.

Breathing mods are usually next up. Contrary to popular belief there is generally very little if any power gain reached by fitting an induction kit, they only help and are recommended after you boost the engines power to the point where the standard air intake box cannot cope!

Maximum power gains come from a full induction kit with a cold air feed on heavily tuned engines, this can be sited within an air box but a panel filter should suffice for most applications. TorqueCars suggest you use a panel air filter as these are easy to clean and maintain and generally perform better than paper ones.

Remus make a good range of exhausts for BMW and they have now released an option for most 4 series engines.

We highly rate Akrapovic, Dinan and Corsa exhausts. The OEM particulate filter is not that well designed, and can be improved with a carefully designed larger bore aftermarket system.

Sports exhausts can usually air flow from the engine but do not go too big or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to around 2.5 inches to maximise flow rates, and this should take into account the amount of air your engine is moving.

Polishing and porting the head will allow you to maximise your air/fuel charge. Leave this to a professional though with a proper flow bench and machine tools When you heavily modify your 4 Series you will see that the standard clutch starts to complain so get an uprated clutch. The best mods we would do for your 4 Series are fast road camshaft, remap, induction and exhaust, suspension.

Remaps offer phenomenal power gains on all turbo charged cars. On NA (naturally aspirated) engines the benefits are doubtful. However a tune/remap on a NA (naturally aspirated) engine will help unleash the potential if you have done a lot of mods. The most phenomenal power gains for NA (naturally aspirated) engines usually involve the addition of forced induction. It is generally simpler to bolt on a supercharger than it is to fit a working turbo. It is difficult to map fuelling with a turbo as the boost comes on exponentially with revs.

Superchargers, however will give a boost which is correlating to engine speed so is easier to map. To cope with forced induction you will usually need to decrease the engines compression ratio .

4 Series Alloy wheel upgrades.

Because alloy wheels are lighter they improve performance and they help to cool the brake disks. If you are serious about performance then you will need to carefully choose your tires - ideally with a soft compound tire. Large 4 Series alloy wheels can decrease performance. If you get big alloy wheels you will be changing your final drive ratio.

With this in mind we would advise sticking to a maximum wheel size of 18 inches, although we know some of our members have fitted larger wheels with no problems.

If you would like to know more, or just get some friendly advice on Tuning your car please join us in our friendly forum where you can discuss 4 Series options in more detail with our 4 Series 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.

Tyre choices are important, the car needs all the grip it can muster, and tends towards being a little tail happy even in standard tune.

The following are not exhaustive, but are tyres that 4 series owners have fitted and rate highly.

• Michelin Pilot Super Sport Tires
• Toyo Proxes T1 Sport Tires
• Hankook Ventus V12 Evo2 Tires

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