We have a lot of love for the E46 chassis here at ECS. Truth be told, it used to be a black sheep, of sorts because it sat in the middle between beloved classics and contemporary performance models in BMW’s lineup. The E46 was a drastic change in visual design for BMW, with a rounded exterior, highly stylized headlights, half-frame doors, and modern interior elements. It was less of a niche enthusiast vehicle and seemed to compete with the popular commuter cars more than performance coupes. That was just what consumers demanded at the time. Now, as E30 and E36 prices soar and E9X prices remain fairly high, the E46 has once again become a common choice among enthusiasts as a project car for street or track use. That means, once again, folks are interested in modifying them. The question is, what upgrades are worth it?
An intake is the perfect first upgrade, but it’s not going to give you a ton of power. The point is to reduce intake air temperatures and improve airflow to allow your engine to continue performing under harder conditions. You might gain a bit of power, but not much. Still, an aftermarket intake that is designed properly, like the DINAN intake for your M54, is a must. The biggest benefit is from the reduced intake temperatures and resistance to heat soak gained with a sealed intake system. This setup allows your M54 to continue performing longer and pairs well with other similar modifications on this list.
As we said, it’s difficult to add power to the M54 without stepping up to forced induction. But what about the power it already has? Every engine drives more than just the wheels; power is lost to the alternator, power steering pump, A/C pump, and water pump. This is known as ‘parasitic loss,’ as those accessories take power from the total power available and divert a portion of that power away from the wheels. You can always delete power steering and A/C, though that isn’t advisable. Regardless, you’ll still need to run the alternator and water pump if you want to drive your BMW longer than 20 seconds. Fortunately, upgrades like Turner Motorsport’s Power Pulleys help reduce some of that loss and bring back a bit of the power. In the case of the M54 pulleys, you can expect about 11hp gained back with this kit. It isn’t creating more power, just using what you already have to do something more fun!
With the M54-powered 330i, you’re never going to see massive performance gains from bolt-ons like modern turbocharged engines have, but that doesn’t mean you are wasting your time improving something like the E46. With the intake and pulleys already mentioned, you’re looking at a fairly stout horsepower increase. By adding a full exhaust system, you can pick a few more HP up, reduce weight, and improve your overall driving enjoyment all at once. Of course, cat-back exhausts are quite popular due to the lower cost, but you aren’t gaining anything other than sound. For a measurable upgrade, you’ll need to replace the whole system. However, there aren’t too many off-the-shelf options available that are street legal. For street driven cars, a cat-back or muffler is all you can do. Unfortunately, you won’t be making any power gains from this upgrade, but it will sound nice.
Unlike a cat-back, a software upgrade will improve your power delivery and overall engine performance significantly. By maximizing the efficiency of your software maps, a plug-and-play tuning device like Shark Injector Software can give you a serious bump in power, especially with the power pulleys, intake, and exhaust already installed. Think of it like the bow that ties everything together.
Ok, this isn’t a performance upgrade, but it does affect your M54’s performance. A failing VANOS is usually easy to spot, or rather, hear. It will sound like marbles in a tin can if your VANOS has completely failed. A common problem, though, is a VANOS that is not exactly failed, but isn’t engaging properly and will eventually fail. After more than 100k miles, you may be losing power to poor VANOS function. Fortunately, it’s not a terribly difficult fix and we have a full VANOS rebuild kit as well as for instructions on how to repair your VANOS yourself. This is a critical service if you plan on making power with your E46.
Finally, another performance upgrade that doesn’t add power: drivetrain mounts. The OEM BMW engine, transmission, subframe, and differential mounts are all rubber and soft. If they’re the original mounts from your E46, then they’re also likely ready to be replaced. With the OEM rubber, you’re losing some power to drivetrain deflection, though, so why replace when you can upgrade? Polyurethane drivetrain mounts are an excellent upgrade for a street driven BMW that will help resist drivetrain deflection, give you a more connected feeling behind the wheel, and won’t induce too much NVH. However, if you want zero deflection and don’t mind the additional noise, solid aluminum drivetrain mounts are another option.
It should also be mentioned that the E46 chassis has notoriously weak and failure-prone rear subframe mounts. With the rear subframe out, you can inspect your E46 for any existing damage, repair it, and future-proof it with Turner Motorsport Subframe Reinforcement Plates. When you replace or upgrade your rear subframe mounts, you should also do this.
Naturally, this is an entry-level list and nothing groundbreaking. However, for a more enjoyable and engaging driving experience, the intake, pulley, exhaust, software, and drivetrain upgrades listed here will do wonders. Any E46 330i should start with this list before doing anything else to the car other than basic maintenance.