BMW Z4 (E85/E89/G29) Tuning

"Thanks for reading my BMW Z4 tuning tips."

The Z4 Roadster was launched in 2002 and designed by Anders Warming. It replaced the Z3 and an E89 version came out in 2009 followed by the G29 in 2018.

The Z4 is a awesome project car to try. The whole chassis design and range of engines make the Z4 the ideal car tuning project, and thankfully there are loads of quality performance parts around for them.

We love the look of the Z4, its sharp handling and interior design.

Before you start modding your Z4 take your time and research Z4 tuning with a specific goal in mind, this will save you from making the usual costly slip ups we typically hear people complain about.

Z4 Handling/Suspension upgrades

Improving the handling for most drivers, is rated as a top priority mod in your Z4 tuning project.

Good suspension tweaks that often enhance handling for the Z4 include a couple of degrees negative camber and somewhere between 1 to 1.5 degrees of toe in or out on the front wheels. Toe in for stability, or Toe out to improve cornering. It would also pay to improve the brakes, by adding larger discs and or higher friction pads..

A front strut brace will help keep the front suspension geometry setup correctly even under heavy cornering and as the car gets older.

A set of adjustable coilovers such as the V3 versions supplied by KW and H&R sway bars on the front and rear or look to Eibach for other options.

Some owners have replaced worn bushes with Polyurethane ones from Powerflex but in my personal opinion they transmit too much vibration from the road to the car.

We suggest that you fit sports suspension and lower the car by 30mm - 35 mm. Larger drops require arch work - especially on models already equipped with performance suspension.

Don't just look at the peak power figures, you need to see the whole torque curve when determining if a mod is right for you Z4.

Fitting a set of larger drilled vented and grooved brakes will make a big difference, Brembo seems to be the go to Z4 option but we've seen good things from Ksport if your alloys are big enough.

A decent set of brake pads for your Z4 would help whether you've upgraded the disks or not, we like Mintex pads and Pagid but avoid race compound pads, as these can be shockingly ineffective on the roads when cold.

Tuning modifications.

• 2.0 L N46 i4 148bhp (Europe only)
• 2.2 – 3.0 L M54 I6 175 bhp
• 2.5 – 3.0 L N52 I6 174-215bhp
• 3.0 M53B30 - 215 - 228bhp
• 3.2 L S54 I6 (Fitted to the M versions offering 338bhp)

E89 engines (2009 to 2016)

• 2.0 L N20 turbocharged i4 154 - 181bhp
• 2.5 L N52B25 201bhp
• 3.0 L N52B30 I6 255bhp
• 3.0 L N54B30 twin-turbocharged I6 302bhp
• 3.0 L N54B30T0 twin-turbocharged I6 335bhp

G29 Engines (from 2018)

• 2.0 L B48 turbocharged i4 189 - 255bhp
  3.0 L B58 turbocharged I6 335 - 382bhp

Engine power was lower on many US versions due to fuel and emissions differences.

This list of the stages and motorsport kits are usually installed by our members, decide how far you want to go before you start.

Getting the correct grade of motorsport mods 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.

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

Best mods for your Z4

1. Z4 Suspension - Fitting a more sporty Suspension kit greatly enhances your Z4 road holding and cornering. Coilovers and Bushings are the usual go to mods
2. Intake Mods and Performance Exhausts - Be aware on their own these mods will NOT ADD POWER on most cars, but they enable you to lift power after other modifications by lessening the restrictive flow.
3. Flywheel lightening - a lower mass flywheel will enhance the engines rev changes. Not always not a great upgrade for all Z4 engines.
4. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.
5. ECU Tunes - A Remapped Z4 ECU offers the biggest gains in terms of cost, aftermarket ECU upgrades, and piggyback ECUs are all alternatives.
6. Turbo upgrades - Adding a turbocharger is the most efficient approach to increase your intakes air supply, this means you are able to combust more fuel and make more power. Typically one of the most costly modifications it does provide the largest gains.
7. Brake Mods - Enhancing your stopping power needs to be high on your agenda.
8. Fast road Camshafts are generally the biggest mechanical mod upgrade, but ideally be fitted by someone competent and tracking one down can be a challenge but there might be a local firm to regrind a stock cam .

Z4 Tuning Stages

Typical stage 1 mods often include: Panel air filter, Lighter flywheel, Sports exhaust, Alloy wheels, Engine Tunes/Remapping, Suspension upgrade (drop 30mm - 35 mm.).

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

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

You need to keep as much low end power as you can and aim to get a wide power band across the rev range rather than a narrow top end power hike.

In this article we shall give a limited introduction to the best mods for your car, but we'd encourage you to spend some time on the site looking into the details of each type of performance modification.One of the best mechanical tuning modifications you can do on your NA (naturally aspirated) engine is to fit a fast road camshaft .

The intake and exhaust durations play a major role 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 cam upgrade with other mods and finish with a reflashed ECU to fully realise your gains.

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

If you find you experience flat spots and power surges after your uprated parts you should check the fuelling and try a higher octane fuel as well.

To get sufficient fuel you may need to improve the injectors on your engine.

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.

Remove the limiter whilst you are getting the ECU remapped, it will help on those track days if you can hit a proper top speed.

Z4 Intake and Exhaust Tuning.

The next area for modification is the intake and exhaust. Please note that WE DO NOT SEE IMPROVEMENTS WITH INDUCTION KITS, unless you have tuned your car with over 30 percent more power and are finding that the standard air intake has become a restriction.

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.

Sports exhausts increase the flow of gases through the engine. But if your exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose much of your flow rate and end up sapping power and torque.

Remus exhausts work really well on the  Z4 but there are loads of performance exhausts to choose from, the header design is the most important part and a sports catalyst will free up the top end.

Airflow through the head can be dramatically increased with some professional gas flowing. These should match and be setup to take into account any other engine mods. In nearly all cases of Z4 tuning your clutch will start to suffer and this needs an upgrade - read our overview on clutches for more information.

The best mods in our experience for your Z4 are remaps, sports camshafts and induction improvements.

A tuned/remapped turbo will give phenomenal power gains and fully release the potential power of the engine.

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.

Investigate the Vortech v3 charger kit from VF engineering for the NA (naturally aspirated) engined Z4's, which will make pretty good power.

We've also come across some owners experimenting with twin charging applications and making some seriously high power hikes.

The most phenomenal power gains for NA (naturally aspirated) engines usually involve the addition of forced induction. Superchargers are generally easier to add than turbos. Turbos increase power in increasing proportion to rising engine speed and this can make mapping difficult.

The nice directly proportional boost and rpm characteristics of the supercharger make them simpler to map. Decreasing the engines compression ratio will allow you to add forced induction, water injection may also help prevent detonation.

Z4 Alloy wheel upgrades.

Get rid of those run flats, they are heavy and we would recommend fitting Bridgestone Potenza, Goodyear Eagles F1 or Michelin Pilot Sports, Pirelli P Zeros, or Continental tires on the Z4.

Alloy wheels can help the brake cooling and are usually less heavy than steel ones. Pay attention to your choice of tyres (tires) for your car, a good directional tread pattern tire can really enhance your cars handling. Large Z4 alloys can decrease performance. If you get big alloys you will be changing your final drive ratio.

Due to this fact we would advise sticking to a maximum wheel size of 18 inches, although we know some of our members have gone larger than this with no problems.

Rear tyres are better wider than the fronts, typically you'll put 8.5" on the fronts and 9.5" at the rear, it will help with traction and handling.

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 Z4 options in more detail with our Z4 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.

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