BMW E46 Tuning

"What are the best E46 mods?"

A site visitor asked for more information on the E46 and how to tune it up and modify it, so we've created this feature to take you through what we feel are the main modifications that we rate and are the greatest parts you can do to this engine.

This fourth generation 3 series had a production run from 1997 to 2006, and the M3 model arrived in 2001 showing what this awesome platform is capable of.

The focus was to create a lighter, but more rigid car and much was made of the 50/50 weight distribution.

The E90 replaced the E46 series, and this phasing out occurred around 2004, with the cabriolet (open top) version still sold until 2006.

The E46 has become very popular, enjoys a vast array of tuning mods and parts from carbon fiber trim to high tech engine mods, so we'll break down what we feel are the best mods for your E46.

Most look to the M3 and Alpina versions for inspiration as these are very nicely designed, built and setup, but the E46 chassis is capable of even more with the right mods and setup.

We are not sponsored so you'll only get honest unbiased advice from us, and we encourage you to use the comments below to pass on your tips and help us improve this article.

The E46 is a good tuning project to fill your spare time. We see DIY mechanics wasting money on their E46 doing the wrong mods and then having to start over.

All wheel drive was offered in the E46, a great setup that really improves the wet weather performance of the 3 series range. We also saw valvetronic introduced on the engines, BMW's take on variable valve lift and durations.

Follow our hints to avoid ruining your car. In some regions BMW offered a performance package, which improved the 330i, by optimizing the cam profile, reducing the gear ratio and revising the suspension with more negative camber and better anti roll systems.

This gives us a hint at the areas to focus on when modifying your E46, and there are some very good parts around, but the choice will vary depending on which region you live in.

Tuning tips and articles

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

E46 Engine tuning mods.

Please watch our video which covers the 5 principles of tuning your E46. Be sure to subscribe and support our new channel.

Best mods for your E46

  1. Mapping - E46 remapping gives the most power compared to cost, replacement ECUs, and Tuning boxes are all alternatives.
  2. Turbo upgrades - A New Turbo is the most dramatic method to improve intake air supply, ensuring you are able to utilize more fuel and make better power figures. Although one of the most technically difficult mods it does provide the largest gains.
  3. 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.
  4. Intake and Exhaust Upgrades - NB: on their own these mods won't ADD POWER , but they can help release power after other mods by lessening the restrictive flow.
  5. Fast road cams are are often the best upgrade for an engine, but they must be fitted by someone who knows what they are doing and tracking one down may be hard but you might find a local firm to regrind a stock camshaft for you.
  6. Brake Mods - Improve your E46's stopping power needs to be high on your agenda.
  7. Lighter flywheels - a lower mass flwheel will improve the engines ability to rev freely. But not always suitable for all E46 engines.
  8. E46 Suspension Upgrades - Upgrading your suspension dramatically improves E46 handling Poly Bushes and Coilovers are typically fitted to achieve this

E46 Tuning Stages

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

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

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

E46 Handling/Suspension upgrades

Improving the handling for people first priority in your E46 tuning project.

Over time the strut mounts will deform and move, a noted weak area, so fitting a strut brace will help keep the alignment, but the shock tower itself was made as light as possible.

This creates a weakspot and we would urge you to buy some reinforcement plates to prevent these issues from happening, because when it does you end up with a costly repair.

If you set the toe out to 1-1.7 degrees on the front, and add some negative camber then cornering will usually benefit.

We would go to a maximum drop of 29mm - 42 mm. on most models. You risk grounding out if you go lower than this. It also allows the tires to sit in the arches without the massive gap.

Check out Eibach, Vogtland, Bilstein and Koni kits, all have a good reputation among our members.

We would also recommend you look for an adjustable set of coilovers if you can, this allows you to adjust your cars handling to suit you.

Upgrading your Bushes

What factors should you consider when setting up and selecting your bushes if your E46 is also used as a daily driver?

It is possible to connect the E46's suspension components to the chassis of the E46 using poly bushes, which are drop in replacements for the rubber mounts. The rubber ones will degrade with time and need replacing anyway so why not upgrade.

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 more harsh, but they will last longer and maintain the handling.

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

With a new set of polyeyurothane bushes, the excessive play associated with rubber bushings may be minimized.

Some poly bushings are hard to locate, but most will find the primary mounts readily available in their regions You may be able to have custom polyeyurothane bushes created to suit your needs.

A common misconception is that a non-adjustable suspension system that lowers the vehicle by70mm from a franchised component shop is the best option. But suspension design and setup is quite complex.

Vendors may assert that their E46 suspension kits are compatible with any or all of the E46 model years.

For a vast variety of vehicles, a 'compromized' approach is obviously incorrect.

E46 Brake Upgrades

Better brake pads should be paired with bigger brake discs in order to provide significantly greater stopping power.

Remember that racing pads may grind and need to be hot before they bite, just in case you were wondering.

Because the brakes are seldom utilised in daily driving, they will not be effective, therefore choose low-working-temperature brake pads.

With the E46, you should strive for maximum top-end power and a broad peak torque range.

To create the perfect sleeper, keep your vehicle appearing stock and remove all of the insignia.

Start with a larger engine rather than a smaller one since the power return from a smaller engine is little. If your engine is tiny, you should consider an engine exchange.

E46 Engine Tuning mods.

These are the mods, kits, and upgrades that are usually installed by our members, decide how far you want to go before you get going to avoid wasting time and money on the wrong mods.

Fourth generation 3 series (E46; 1997–2006)

All wheel drive was offered in the E46, a great setup that really improves the wet weather performance of the 3 series range. We also saw valvetronic introduced on the engines, BMW's take on variable valve lift and durations.

Petrol options

  • 1.8–2.0 L M43/N42/N46 I4 with power ranging from 103hp to 114hp
  • 2.0–3.2 L M52/M54/S54 I6 with power ranging from 148hp to 355hp

Diesel:

  • 2.0 L M47 I4
  • 2.9–3.0 L M57 I6

The more powerful variants generally provide better returns for your tuning investment, although in the S54 most of the mods you would want to do have already been carried out as BMW extracted as much as they could from this block.

Getting the best performance modifications for your planned usage of the car is vital. Stage 3 (competition) mods just don't work well on the road difficult in stop start traffic.

In this article we shall give you a good starting base to the best modifications for your car, but we'd encourage you to spend some time on our site looking into the details of each type of performance part, we've included some links below to the common areas, but tuning cars becomes quite a deep rabbit hole!

Peak power is good on competition cars but for a daily driven car you need a wide power band and perhaps extending the rev range.

Beware of peak power gains, these don't tell the full story and often parts will move the power band up, leaving you with a deficit of torque in your usually used region of your rev range.

One of the best mechanical modifications you can do to your NASP engine is to fit a fast road camshaft. This also works on a turbo, but a remap is by far and away the best return you'll get for power to cost ratios.

We note that in some regions these can be hard to source, but more and more places are offering a regrind service on your stock cams to provide the duration and lift you want. Beware though, sometimes you can lose lift if the cams are not designed properly or are wrongly installed.

It improves the intake and exhaust durations and increases the power if done right. Ideally, you'd add other mods to maximize these gains, and finally would finish up with a reflashed ECU.

We'd also caution you not to go with a "competition cam" as this affects the engines idling and general town driving characteristics.

E46 fuel upgrades

When pushing up the power you will need to pay attention to the fuelling. More power needs more fuel, this is the simple principle of performance tuning a car.

Using higher octane fuel is another option if you find you are suffering from pinking or premature ignition on your BMW project after fitting other sports kits.

Uprating the injectors is another beneficial modification and will deliver sufficient fuel. Using parts from the S54 is a good easy way to increase power on some of the other engines in this range.

Uprate the fuel pump to cope with the extra fuel requirements of your tuned E46's uprated injectors.

E46 Intake and Exhaust Tuning.

Now we move on to the intake and exhaust and ensure proper flow through the engine.

Please note that WE DO NOT FEEL YOU GET POWER GAINS FROM INDUCTION KITS on the E46, unless you have tuned your car with over 30 percent more power and are finding that the standard air intake has become the bottleneck.

At the most you'll get 2% more top end power, and some owners have noted flat spots and lumpy running after fitting an induction kit with no other mods.

Always fit a cold air feed instead of an open cone filter which will suck in warm air from the engine bay.

Your money is better spent on the intakes throttle body where you should see a noticeable power gain of around 5%.

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

Getting a professionally gas flowed head with larger valves can fully release the engines power. A good triple plate fast road power clutch will help to keep that power going where it should. Never make false economies or expect the standard OEM clutch to cope. The best mods in our experience for your E46 are remaps, sports camshafts, and induction/exhaust improvements.

E46 remapping

Remaps offer significant power gains on all turbo charged cars, even those already setup for high performance. On NASP engines the benefits are doubtful but not insignificant netting around 10hp-20hp more power and it does change the torque curve making the car more pleasant to drive.

However a chipped or remapped ECU on a NASP engine will help unleash the potential if you have done a lot of mods.

We strongly recommend a rolling road remap if you've done other mods, because the off the shelf approach will only deliver an averaged safe power gain, and most cars will respond better if their mods are all taken into account.

Expect to service the car more frequently after a remap, after all the engine is working harder. A remap will also highlight weak areas in your car, the clutch is quite a common point of failure, but old worn injectors, ignition system issues and carbon deposits can all cause rough running which may not be noticed.

There are quite  few specialists out there offering performance maps, there are modules you can plug into your ECU to flash it, and there are various tuning boxes and piggyback ECU's and chip replacement options.

Learn the pros and cons of each of these options before you commit, and we've covered these in great detail in our site, so use that search button to find them and research your purchase carefully.

Despite the large cost involved adding forced induction to a NASP engine will give large power gains.

Running a low boost setup will give a decent power gain, but for the best results you should lower the engines compression ratio, improve the fuelling and provide an aftermarket ECU to allow you to fully optimise spark advance and the fuel maps. (Remapping is also a possibility but the results will vary depending on the ECU fitted to your car.)

Superchargers are usually easier to add than turbos. With a turbo the power curve is related exponentially to the engine speed making it harder to map.

It is simpler to map a supercharger because the boost is proportional to engine speed on a linear curve. To cope with forced induction you will usually need to decrease the engine compression ratio .

E46 Alloy wheel upgrades.

Alloy wheels can help the brake cooling and are generally less heavy than steel ones.

We can't go into too much detail here about tires and will save this topic for another day, but the tires are essential it's how the car puts the power down on the road so will have a big impact on performance and we find that budget tires should be avoided, check out the videos on our youtube channel for more insights on tires.

Soft compound tires work well on E46, and make a big difference over budget tires. Please note although they can look cool on the E46 big alloys will actually decrease your performance. The larger you go the lower your acceleration will be - this to the change in your effective final drive ratio.

Although some people have installed larger rims without problems we would stick to a 16 inch rim size as the maximum.

19's are about as large as you can go, but they will be quite crashy and detrimental to the cars handling, so we would recommend 17's or 18's.

Personally I like the VMR range, the spoked wheels look really good on your E46, but alloy choice is subjective, and all we would urge is for you to choose lighter wheels.

If we are honest, the 17's are the pick for everyday driving on wet roads, they won't pick up scrapes and scratches like the larger alloys and most drivers prefer the driving feel they offer. This does fly in the face of most "MOD YOUR CAR" websites and forums where bigger is always perceived as better but in our opinion handling and performance are more important than looks.

For more information on Tuning your car please join us in our friendly forum where you can discuss E46 options in more detail with our E46 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. Comments are used to improve the accuracy of these articles which are continually updated.

Check out my YouTube channel, we're regularly adding new content...


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