BMW has come out with many engines in their time, but perhaps the most celebrated one is the M54 engine, which was originally produced for the E53 X5 and was eventually replaced by the N52 engine.
It has previously been listed among Ward’s 10 Best Engines, as well. If you’re a BMW fan, how much do you know about this iconic and award-winning engine? Read on and you’ll learn everything you ever wanted to know but were afraid to ask.
BMW M54 Engine Background: Replacing the M52
The BMW M54 is a straight-6 gasoline engine, naturally aspirated and so without a turbo. It was first introduced to the line in 2000 as a replacement for the M52 engine which was in use between 1994 and 2000. It went out of production in 2006 but was still used in its high-performance S54 format until 2008. It had some important differences from its predecessor, including:
- A non-return fuel system
- A fully electronic throttle with no mechanical backup unit
- Siemens MS 43 engine management
- A new intake manifold
- A new aluminum block
Displacement levels ranged from 2.2L to 3.0L on the M52, but there was also a high-performance variant known as the S54. This was used on the models such as the E46 M3, the Z3 roadster and the E85/E86 Z4 M.
Variations of the BMW M54 Engine
In all there were 4 variations of the M54, including the high-performance S54. Below you can find their essential stats:
- M54B22 - 2.2L, 168-hp, 155 lb-ft of torque, used from 2000-2006
- M54B25 - 2.5L, 189-hp, 181 lb-ft of torque, used from 2000-2006
- M54B30 - 3.0L, 228-hp, 221 lb-ft of torque, used from 2000-2006
- S54B32 - 3.2L, 338-hp, 268 lb-ft of torque, used from 2000-2008
Because there was never any technical update for the M54, it continued in these same forms for the entirety of its lifespan. What we mean, of course, is that in terms of the manufacturer’s specifications, there were no major changes or updates made before it was eventually replaced with the N52 engine. Many private individuals and specialist auto shops actually did a lot of different work to make sure that the M54 engine could stand out quite a great deal.
BMW S54 Engine
Although it wasn’t technically an M54, the S54 was still regarded as being “within the family.” The truth, however, is that despite the closeness of the names of these engines, they actually weren’t as closely related as they seemed. The S54 engine was based more closely on the BMW S50 engine, and actually shares very few identical parts with it's step-sibling. It also has a cast-iron block where the M54s were made with an aluminum block.
The S54 was the last of its kind in the straight-6 category. It was eventually replaced in 2008 with the BMW S65 engine, which was a V8 and so the line of straight-six engines ended. The S54B32 engine was used in the E46 M3, the E36 M Coupe and Z3 M Roadster, the Wiesmann MF 3 Roadster, and the E85 Z4 M Roadster and Coupe models.
With pricing in the used market going wild during the pandemic, E46 M3's are becoming rarer and rarer. This story of finding the perfect one highlights the brand's continued fandom.
M54 Engine Mods
The durability and quality of the M54 has led it to become a favorite among those who love all things about car modification. In this section we’ll look at different ways you can mod the engine to boost its performance. With variants offering between 170 and 228-hp, it’s easy to see why some in 2021 would want to modify the engine to get a bit more out of it.
Bolt-on BMW M54 Engine Mods
Let’s start by looking at the bolt-on mods that were available. To be clear, “bolt-on” modifications refer to those in which the modder can remove an OEM part and replace it directly with an aftermarket part. There’s no additional reprogramming or remapping, nor are any specialist tools or top-level skills required as with some other jobs. The M54 had six common main areas where people were modding, which we’ll detail below.
At the top of the bolt-on mods list is a set of new headers. New headers will set you back only about $70 and can gain you a very handy 15 horsepower of additional power. There is a snag, however, and that is if you want to keep it this cheap, the most likely outcome of that is you having to remove the cats. This can cause problems with emissions and can render your car unroadworthy.
Is there a way around this? With more money, you can certainly invest in a set of high-flow catted headers, but it will raise your cost significantly. If you’re planning on using the car in a racing setting only and won’t take it on the public roads, then this doesn’t have to be a problem. If, however, like most people you do also wish to drive your M54-engine car on public roads, then you have a choice to make.
A set of cold air intakes is usually the ticket to boosting performance on an M54, same as many other engines. The stock air filters on the M54 are quite small, but you can improve things by installing a larger, high-flow filter that has straight, smooth ducts. The result of this filter switch means that the engine is pulling in cold air faster, which ultimately means more oxygen fueling combustion.
What makes intakes a good choice of mod for the M54? The main benefit is the cost-to-hp-gain ratio, which is quite good; far better than it is for an exhaust gain. For the total expense of about $100-200, you can gain a boost of up to 7-hp. It doesn’t sound like a lot, but an exhaust mod can cost 10 times more for fewer horsepower gained (see below).
Exhausts are a common mod made to cars, and work perfectly well, but the main thing is not to expect too much of a gain from it. Exhaust mods will give you additional sound depth from the engine, but won’t deliver much in the way of performance enhancements, no matter what sellers of exhaust mods claim. The typical BMW M54 exhaust mod can only add up to about 5hp of additional power. That’s for a mod that can cost as much as $1,000 to purchase and put into place.
The main thing that exhaust mods do for your engine and car’s internal working is to remove some of the pressure that builds up by allowing exhaust gases to escape from the exhaust faster. While some assume that they will bring performance benefits, these gains are far less likely to materialize compared to those you can get from installing new headers in the M54.
As we mentioned above, the exhaust mod is most effective when it comes to enriching the sound coming from your M54. The mod can be expensive, but there are plenty of choices out there for BMW exhaust mods, so you can shop around to find something that meets your needs and is within your budget.
A nitrous mod goes very well with the BMW M54 engine because of its naturally aspirated design. The main downside to a nitrous mod is that it doesn’t provide continuous benefit. It can be called upon to provide a shot of additional power at a critical moment, which can be very useful of course, but it’s not a continuously operating modification.
Nitrous kits are not so expensive, costing roughly $450 or so and they are sold in different shot sizes measured in the boost of horsepower that they’re meant to give. Most people start by adding somewhere from 35-hp to 75-hp per shot, but there are bigger shots available. For the vast majority of modders however, something within the 35-75 horsepower range proves to be more than enough of a boost.
Switching out the M54 camshafts for performance camshafts is a good way to gain 5-10 horsepower, but that small gain comes with a big price in terms of labor and difficulty. Replacing the camshafts is not an easy task at all. If you can DIY install them yourself, then you’ll save a lot of money but even the more experienced modders will admit that you cannot get around the amount of time needed to do the job right.
With this M54 modification, the best idea is to think carefully about whether you need those additional 5-10 horsepower. Using a forced induction mod (see below) you can make much bigger gains, so why bother with such a troublesome mod that only delivers a paltry 10-hp max? The additional 10-hp is a very attractive proposition for anyone using their M54 on the track. Even an extra few horsepower in a race can be enough to pass an opponent on a critical final turn and take victory.
You can use both turbos and superchargers to boost horsepower and torque, thus getting a lot more performance from your BMW, but there’s a downside to doing that. These methods both put more strain on the engine, and are also expensive. Turbocharging kits can range from $4,000 to $7,000, but they can take the engine from its top rate of 228-hp into the range of 320-hp or more, even as much as 400-hp.
The general rule of thumb when it comes to using these forced induction methods is that the more you want to add to your horsepower rating, the more additional mods that you’ll need in support. This is the main reason that the price for this modification type can range so high. If you’re chasing greater power gains, then you’ll have to back up your forced induction upgrades with fueling, tuning, traction and other areas of improvement on your car, too. If you have the budget for that, then it’s a good and direct way to get more out of the engine.
Increase Valve Size
One final thing you can do is to boost the valve sizes on your M54. This along with some port matching and head flowing adjustments will see some pretty good increases in power, though it varies from engine to engine. The best thing about this method is that you can also boost the power and efficiency of your other bolt-on mods.
Other Mods: Remapping
If you’ve installed any and all of the above mods, then you’ll want to get the most out of them that you possibly can. To do that, the most effective route is remapping your car’s ECU. Now, some cars come with a locked OEM ECU that can’t be tampered with in this way, so if that’s the case on your own car, then you might have to consider first purchasing an aftermarket ECU to use instead. This will typically cost anywhere from $150 to $1500.
When done properly, an ECU remapping can add around 30 percent more power on a turbocharged vehicle, but if your M54 is still naturally aspirated with no turbo installed, then you may only see increases of 15 percent. That’s still very strong, however.
The BMW M54 Engine: Still Ready and Raring to Go!
The BMW M54 engine may already be two decades old, but it still packs a punch that many people want to see under the hood of their car. As a perfect candidate for modding, it’s no surprise that people still seek vehicles that carry the engine, or would seek to use it in their own vehicle.
It’s critical to remember that whichever M54 engine mods you choose, take care not to spend needless money that delivers no result while accidentally rendering your car unworthy of the public roads in the eyes of the law. To do so would end up costing you even more further down the road.