BMW E90 E91 Tuning

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This four-door sedan is one of the compact executive cars from the fifth generation of the BMW 3 series.

As you know the E90 series differentiates by the body style, with a range of saloons, estates, coupes, and convertibles. All part of the generation that ended the naturally aspirated inline 6 era.

The N54 powered 335i made the shift to Turbocharging and the best mod you can go for is the dual cone intakes and engine tuning/remapping to fully release the potential power.

It was the first model of the BMW 3 series to be sold in the market as a 2006 model. It was launched in Mar 2005 and the production continued till a facelift revision was made in 2008.

E90 Engine tuning mods.

Please watch our video which covers the 5 principles of tuning your E90. Be sure to keep up with our latest YouTube content and subscribe.

Best mods for your E90

  1. Braking Mods - Stopping your E90 needs to be somewhere in your mods list.
  2. Fast road Camshafts are significant power adders, but they must be installed by someone who knows what they are doing and you might struggle to find one but there might be a local firm to regrind a stock camshaft .
  3. Intake Mods and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help release power after other mods by lessening the restriction.
  4. E90 Handling Mods (suspension) - Fitting a more sporty Suspension kit dramatically improves E90 handling Poly Bushes and Coilovers are typically fitted to achieve this
  5. Lighter flywheels - a lighter flywheel will improve the engines rev changes. But not always suitable for all E90 engines.
  6. ECU Tunes - E90 engine tuning/remapping ensures the most power compared to your outlay, aftermarket ECU upgrades, and piggyback ECUs are all alternatives.
  7. Flowing and porting the engine head - for larger gains, you will get better flow and make a more efficient engine if you do this to support your other mods.
  8. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase your intakes air supply, which permits you to combust more fuel and make power gains. It is one of the most complex modifications it offers big gains.

E90 Tuning Stages

Typical stage 1 mods often include: Lighter flywheel, Sports exhaust, Panel air filter, Alloy wheels, Suspension upgrade (drop ), Remap.

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

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

The E90 chassis has models with various engine options available. If you are in search of a used 3 series, then go for a facelift or Post-LCI (Life-Cycle Impulse) model. Some of the high-performance post-LCI models of sedan E90 are as follows:

  • 325i/325xi 2008-2012

Gen 1 N52 3.0 liter inline-six petrol engine | 215-hp and 200 lb-ft.

  • 328i/328xi 2008-2012

N52N petrol engine in ULEV (Ultra-low emission vehicle) version | 230-hp and 200 lb-ft

  • 328i/328xi 2008-2012

N51 petrol engine in SULEV (S-Super) version | 230-hp and 200 lb-ft

  • 330i/330xi 2008-2012

N53 straight-6 petrol engine | 276-hp and 240 lb-ft

  • 335i/335xi 2006-2010

N54 3.0-liter twin-turbo engine | 300-hp and 300 lb-ft

  • 335i/335xi 2010-2012

N55 straight-6 turbo engine | 302-hp and 310 lb-ft

  • 335d 2009-2011

M57 straight-6 diesel engine | 282-hp and 403 lb-ft

i’ stands for fuel-injected xi’ for four-wheel-drive system or BMW’s xDrive

After the facelift, some models got an engine update like the BMW 335i model switched from the N54 twin-turbo engine to a single turbo N55 engine.

Another appreciable addition in the line up was 335d, which is a bit tricky to find nowadays. It was phased out after the introduction of the F30 model in Feb 2012.

Now you can only get a used car of this BMW 3 series, and this guide will help you to figure out which specific car you should buy among a long lineup of E90 generation.

One model that keeps popping up in emails and questions we get sent, is the E90, and it's larger brother the E91 and which mods work best on it.

So we've put together this guide which covers our go to modifications that you should tune and outline which modifications we feel are the best.


Tuning tips and articles

Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

You can take the power up by using these kits. The stage-one kit has built-in tunes for a variety of modification levels including a high-flow air filter and an access port.

You just plug in the V3 access port into the OBD2 port to gain full programmability. You can use it as gauges and as a data log too. Stage-one plus kit includes an intercooler and a charge pipe, adding them will further increase the horsepower. You can also add an extra three-inch exhaust system.

E90 E91 Handling/Suspension upgrades

The best change to the look of your BMW is decreasing the stock wheel gap. But this is only the start. Whether that would be springs and shocks, camber, more rigidity in the form of anti-roll bars, or even just ride height lowering.

Drop the car optimally somewhere in the region of 27mm - 42 mm. and fit stiffer dampers, bigger drops will usually need other modifications in most instances to avoid rubbing tires on the bodywork.

An upgraded suspension setup can provide optimum performance in the form of better handling, better overall ride quality and lowering your center of gravity to perform well on the track.

Upgraded springs and shocks such as these Eibach B12 Pro Kits really look the part when paired alongside KONI FSD Shock Absorbers and are popular with E90’s.

H&R Sport Spring Kits can also be a solid choice for a simple coil upgrade.

Lowering your car whilst offering a stiffer setup with tighter handling on the corners. Then, of course, the standout players in this space are from the likes of Bilstein, Vogtland, Eibach & KONI with plenty of BMW tailored kits.

If you set the toe out to degrees on the front, and add a bit of negative camber then cornering will dramatically improve.

Improvements to the bushings

Enhancements to the bushings: Things you need to know

Bushes, which are rubber mounts, allow the E90's suspension components to be connected with the car's chassis. The rubber ones will start to fail as they wear out.

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

It's probable that the ride may be a touch rougher because of the stronger polyurethane bushings but they'll last longer and maintain tighter handling.

Worn bushes may also accelerate the degradation of other suspension components due to the increased vibration and play.

With a new set of poly bushes, the excessive play associated with rubber bushes may be mitigated.

You may struggle to find a full set of polyeyurothane bushes, but most stores have the primary mounts available. Often, custom E90 poly bushes may be manufactured to your requirements.

A frequent misconception is that the best setup would be a non-adjustable suspension system that lowers the vehicle by 80mm purchased from a franchised component shop.

Vendors may assert that their E90 suspension kits are compatible with any or all of the E90 model years.

The 'compromized' approach is obviously a flawed assumption when it comes to adequately supporting a diverse variety of cars. Engine weights and trim levels, and even alloy rims will affect the handling and require different suspension setups.

E90 E91 Brake upgrade kits

Fitting better brake discs and better brake pads can make for dramatically improved stopping. (They will brake effectively over longer periods during heavy use than stock brakes will, but grip has more of a bearing on the cars ability to stop). Brakes come with vented, grooved and drilled discs and there are significant advantages to fitting larger discs as these dissipate the heat more quickly and can handle heavier braking.

Pad choice makes a big difference even on stock discs, so source a decent pad and avoid the cheap budget pads, which have been known to warp/score or damage the surface of the discs (typified in vibrations when braking).

Note that race friction pads can grind and will need a lot of heat before they start to work.

On a road car the brakes are only used rarely, therefore won't be all that effective so source friction pads that have a low working temperature.

Our aim in E90 engine tuning should be to increase peak power and Torque at the top end.

With our guides your E90 can be transformed into a track car and prove to be reliable daily driver.

To be completely frank and honest, on the more modest engine sizes you are wasting your time spending money on modifications, so if this applies to you get yourself an engine swap then apply the following mods.

Best E90 E91 Engine Tuning mods.

These are the uprated upgrades are usually fitted by our members, decide how far you wish to go in your tuning project before you get going.

Getting the correct grade of performance upgrade kits for your planned usage of the car is a time and money saver. Stage 3 motor sport mods just won't work well on the road and will make the car undrivable.

Typical stage 1 mods often include: Alloy wheels, Sports exhaust, Engine Tunes/Remapping, Panel air filter, Lighter flywheel, Suspension upgrade (drop 27mm - 42 mm.).

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

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

E90 series mods explained

The N54 feels like a large NA (naturally aspirated) engine, and doesn’t have the low end lag and sudden on boost feel you get with many turbocharged engines, primarily due to the choice of turbo fitted.

When you modify this you should try to keep the spirit of the original and avoid lag, it will really annoy you otherwise.

As forcing more air into the turbo means you can dial up the boost pressures without worrying about the lack of air and resulting in more horsepower. It is also a simple upgrade and doesn’t involve any invasive engine removal.

  • Weaker turbos are noted on both the N54 and N55 so it makes sense to source a stronger unit, hybrids are popular choices.

The point of our hints is to give a starting base of modifying mods and point you in the right direction, our forum is the best place to go if you need more detailed advice and tips on your modified car project, the best performance modifications and all aspects of modding cars. One of the most cost effective mechanical motorsport parts you can do on your NA (naturally aspirated) engine is to fit a fast road cam.

It improves the intake and exhaust flow and increases the power if done right. Ideally you'd add other mods and finish up with a remap. We'd also caution you not to go with a motor sports profile cam as this upsets the engines idling and general town driving characteristics.

When pushing up the power you will need to pay attention to the fuelling. More power needs more fuel.

Frequently power losses, and erratic idling after motorsport mods are done can usually be traced to fuel delivery or timing issues. Increasing the injectors is another beneficial modification and will deliver sufficient fuel.

A fuel pump will only deliver a finite amount of fuel, so you may need to uprate this if your injectors are demanding more fuel.

E90 E91 Intake and Exhaust Tuning (headers & catback).

Now we move on to the intake and exhaust and ensure proper flow through the engine. Exhaust mods will release a little power, especially if you replace the headers and get a better flowing catalyst, but in the real world, you will only gain a few percent more power.

It is not legal to remove the catalysts in most regions, and in some, you can’t even replace it with a better flowing unit, unless it has started to deteriorate and is due to be replaced as part of routine maintenance.

To boost performance, first thing first, is to ensure your car is running at peak efficiency which won't be the case if it has carbon buildup or fouled plugs.

A good quality exhaust such as the one offered by COBB, will add up to 20-25 horsepower. You can get the removable engine parts out and paint them to stop further rusting, a potential future problem averted.

Please note that WE DO NOT RECOMMEND INDUCTION KITS, unless you have tuned your car a lot and are finding that the standard air intake has become limited.

If you want the induction roar then go ahead, but you won't be getting a power gain, unless you have a restricted air intake.

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 made from cotton gauze, as these are easy to clean and maintain and generally perform better than paper ones.

Sports exhausts will certainly help air flow out of the engine but do not go too large or you may end up will reduce the flow rate. Stick to 1.5 to 2.5 inches for best results.

Getting a professionally polished and ported head with larger valves can fully maximize your power gains. A good fast road sports clutch will help to keep that power going where it should.

Never skimp or assume your standard clutch to cope. The best mods we would do for your E90 are remaps, sports camshafts and induction improvements.

NA (naturally aspirated) engines do not achieve big power gains if you tune/remap them, unless you have done extensive modifications. With turbocharged engines this is another story.

A tuned/remapped turbo will give significant power gains and fully release the potential power of the engine. The most phenomenal power gains for NA (naturally aspirated) engines usually involve the addition of forced induction. It is often cheaper to bolt on a supercharger than it is to fit a working turbo. With a turbo the power curve is related exponentially to the engine speed making it difficult to map fuelling with.

The nice proportional boost and rpm characteristics of the supercharger make them easier to map. Adding forced induction will nearly always require a lower compression ratio or water injection.

E90 E91 Alloy wheel upgrades.

With plenty to choose from, taking an E90 as an example, wheels will set the type of build you want to go for. Making your car have that wow factor right from the offset is a good base point to mod your car around. Going down a path such as track day, VIP, hellaflush, sleeper or stylish daily driver. There are plenty to choose from.

Due to the fact that alloys are lighter, they improve performance and they will help to cool the brake disks. If you are serious about performance then you will need to carefully choose your tires - ideally with a directional tread pattern tire. Large E90 alloy wheels can decrease performance. If you get big alloy wheels you will be changing your final drive ratio.

Another problem is that they come with run-flats, actually pretty skinny tires

Ditching runflat tires is always a good option, these are heavy and hamper the performance, and are also expensive to replace. You will gain in not having to carry a spare but you could always carry a tire repair kit and can still avoid having to put up with a heavy spare taking up space and adding weight.

Wheel choices are very subjective and a matter of preference, but personally I like the multi spoked wheels, which also aid the brake cooling effect, but I wouldn’t recommend large heavy alloys unless you are prepared to sacrifice performance for looks!

For dished wheels, a set of Forgestar F14 Wheels are bespoke to you. Built for your specific needs including unique color, offset and a choice of depth on your dish preference. Fitting extra deep concaved wheels is considered a very aggressive choice. With mods to the suspension, arches, and wings - all to make sure the wheels fit well in the scenes you want to go for, either on the road or track.

Avant Garde Wheels look the part too. The clean design look well on the E90 or F30, their clean design offer that minimalist mod approach but also look the part on the streets at night or at the track.

Whereas a budget friendly option to go for is something from the VMR range. Multi spoke and colour options make your car really stand out without breaking the bank.

Because of this aim to keep the overall rolling diameter of the wheel your OEM settings. In all cases without going larger than 16 inches.

E90 E91 Exterior Mods and Lighting.

Everyone will see the color scheme, wheels, and exterior mods you choose as you drive by on the track, or at car shows and meetups. Therefore, this is a non-extensive list of the options you can go for (as there are so many).

Carbon Fibre rear spoiler – the carbon theme continues with the lip rear spoiler that is s subtle upgrade, but when ramping up the gears on track can actually make that aero difference needed. Making the car stick to the road and shave a few milliseconds off your lap time.

Carbon Fibre front kidney grilles – a mix of abs plastic and carbon fibre make your BMW look the part, with minimal tools or expertise required to make the change. Plus, they can come in a range of colours to suit your build.

M3 Style Front Wings – a simple visual upgrade to make your BMW look as close to the real M3 without breaking the bank. Either by colour matching or unpainted, these steel parts are the go-to choice for upgrading the front of your 3 series.

Angel eye and lighting upgrades – A 3 series may come with Halogens as standard. A simple upgrade is HID with an off the shelf kit. The halo’s or “Angel Eyes” are yellow and warm when they come out of the factory, upgrading these to a whiter, brighter set can not only make you see better at night, but also look the part by having a glaring pair of eyes facing any passers-by. The LUX range is a good option and can fit many models.

Best mods for a BMW E90 E91

When you start modifications on your E90 you need to be aware of the weakspots and problem areas so you can avoid potential problems.

Some of the common problems with E90 E91 models are as follows:

  • Most common issue E90 users face is the short ground clearance, causing scrapes all over the bottom side of the bumper and side skirts.

  • Aluminium bolts for a lot of items in the engine bay like the oil filter housing, solenoids, cam sensors, valve covers, head, crank sensors, oil pan gaskets. All bolts need to be replaced while servicing.

  • Valve cover gasket tends to leak. While replacing check for other broken bolts also.

  • Cam sensors and solenoids may cover with oil. Sometimes cleaning is enough but more often they need to be replaced

  • Carbon-buildup on intake valves results in misfires and stumbles, it does require regular cleaning so schedule a walnut-blast or chemical clean of them every 20,000 - 30,000 miles .

  • Expansion tank hose may cover with leaked oil from the valve cover

  • Oil filter housing has a coolant intake. When the gasket fails, some black gasket mixes with coolant or sometimes coolant mix with oil.

  • Electric water pump can fail without warning and may also harm the thermostat nearby.

  • Oil separator hoses are on intake manifolds may break or crack and are not readily available to get replaced

  • Cabin filter assembly tabs tend to break and bolts tend to strip out

  • In the transmissions there is a plastic oil pan with built-in filters, this whole assembly needs to be replaced whenever you are doing a filter and fluid change

  • High-Pressure Fuel Pump failed and needs replacement.

For more information on Tuning your car please join us in our friendly forum where you can discuss E90 options in more detail with our E90 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.

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 mods work best for them on each model of car. We use your comments and feedback to improve the accuracy of these tuning guides which get regular updates and revisions.

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