BMW M57: Unbeatable and Unkillable

For any of our readers in the US, the term diesel will almost refer to something like Cummins, Detroit, John Deere, International, Ford, GM, Isuzu, and so on.

Diesel engines are popular in heavy-duty applications in the US but not in small applications like standard road cars, which is in stark contrast to many other parts of the world where diesel cars are very popular for their fuel efficiency and reliability.

For that reason, the BMW M57, for the most part, has almost completely flown under the automotive performance radar for the last decade. And that includes me.

I knew companies like Volkswagen produced small diesel engines for small cars, but I, plain and simple, had no idea that BMW’s diesel engine was such an incredible, reliable, strong, and high-performance engine.

With that being said, let’s take a deep dive into the M57 diesel engine and see just what makes it so special.

What is the M57?

While the M57 is generally referred to as the 3.0L BMW diesel you’ll find in the 335D, as well as other applications; it’s actually more than just that singular engine. In fact, there are five versions of this engine in total, with three different displacements depending on the generation, as well as changes to the design and materials used for construction.

The different versions include the M57D25, M57D25TU, M57D30, M57D30TÜ, and the M57D30TÜ2.

The first two have a displacement of 2.5L with power output ranging from 148hp to 174hp. The third engine is a 3.0L, although it’s really much closer to a 2.9L and has power outputs from 181hp to 190hp. And the last two versions are more of a true 3.0L with power ranging from 194hp up to 282hp.

The most performance-oriented version of the M57 and the version most familiar in the US is the M57D30TÜ2TOP with a power output of 282hp and 428lb-ft of torque, and more importantly than that, this version is the only one with an aluminum cylinder block.

For all versions of the M57 prior to the TU2 versions, BMW was using an iron cylinder block, which was and still is pretty standard for a diesel engine, as it’s cheaper and quite a bit stronger, which is important for a diesel engine which is generally going to vibrate quite a lot compared to a gasoline engine as well as produce significant amounts of low-end torque.

Plain and simple, iron is the better material for strength, but it’s much heavier than aluminum, and for applications like the 335D, the weight savings are definitely worth the material switch, so it makes sense why BMW changed it.

Cylinder Head

Starting from the top down, we’re looking at an aluminum four-valve cylinder head with dual overhead cams. As you can see here, the head is bolted to the block with four head bolts per cylinder.

For heavy-duty applications, many enthusiasts prefer six head bolts per cylinder, as you’ll find on a B-Series Cummins, International DT466, and so on, but for this application, the four bolts per cylinder are more than strong enough, especially considering their 12mm diameter which really helps keep the cylinder head clamped hard on the block, even up to 75psi without stretching, which is quite impressive.

For reference, something like the 6.0L Powerstroke is a good example of why many people don’t like diesel engines with four head bolts per cylinder. For that particular engine, the head bolts are well known for stretching when boost pressure is increased past the stock level, so much so that it creates head gasket issues.

Granted, part of that whole problem with the 6.0L is the torque-to-yield head bolts, but the point still stands that four bolts per cylinder are not the preferred layout for a diesel engine.


Inside the M57’s aluminum block, there’s a strong forged-steel crankshaft that’s bolted in place by 2-bolt main caps. More importantly, the rest of the rotating assembly is massively overbuilt.

A lot of people talk about how the N54 is the modern 2JZ and it can withstand crazy amounts of power on the stock bottom end, but what if I told you the M57’s connecting rods are twice the size of the N54’s connecting rods?

The M57’s insanely beefy connecting rods are then paired with cast-aluminum, direct injection pistons with steel ring lands, and the engine is topped off with a composite intake manifold.

In terms of power potential, the M57 is a very capable engine, arguably more capable than the N54. The only weak point that needs to be modified for big power output is the valve springs which can’t quite handle big boost or high RPM.

Timing Belt

As mentioned earlier in the video, on the front of the engine, we have a chain to drive the camshafts rather than a belt.

While a chain is superior to a belt-driven system in terms of reliability, most diesel enthusiasts would prefer a fully gear-driven system as we see on heavy-duty diesel engines, but at the end of the day, this engine isn’t a semi-truck engine, so the chain driven system is more than good enough.

OEM Sequential Turbocharger

The important part of the BMW M57 that allows it to perform as well as it does is the OEM sequential turbocharger which is comprised of two BorgWarner turbochargers.

The small unit is a K39 which is very small and responsive, giving the M57 loads of low-end power. The larger unit is a K26 which comes alive at high RPM and it works alongside the K39 to provide maximum power output.

It’s also worth noting that different versions of the M57 use different turbo setups, and the aforementioned sequential system applies specifically to the M57D30TÜTOP. That unique turbocharger setup allows the M57 to produce upwards of 400hp and 600lb-ft of torque with bolt-on parts and tuning.

Injection System

As with any diesel engine, the injection system is vital to performance, efficiency, reliability, and tunability, and this is yet another area that BMW knocked it out of the park with the M57 by going straight to Bosch for the CP3 injection pump.

That’s right, the M57 is equipped with the same CP3 pump that you’ll find on the 6.7L Cummins as well as many Duramax engines.

Okay, well, that’s only partially true.

This CP3 is the R70 model, which is a different version from the CP3 found on the larger Duramax and Cummins engines, but the point still remains.

This injection pump is capable of producing 23,200-psi worth of rail pressure, and it’s paired with fast-firing, multi-event piezoelectric injectors.

For high-performance M57 engines, tuners will generally add a second CP3 injection pump to support larger injectors, and that kind of setup will generally be good for just under 700whp and 1000lb-ft.

Again though, it’s worth noting that the earlier M57 engines used different injectors that didn’t offer as much performance as the later piezo injectors.

Emissions Systems

As with all modern diesel engines, the M57 is unfortunately equipped with all the emissions components that we all love to hate. These include the diesel oxidation catalyst, diesel particulate filter, selective catalytic reduction with diesel exhaust fluid, and exhaust gas recirculation.

As compared to many other diesel engines, these components can be fairly reliable, with the exception of the SCR and DEF system, which is well documented as a source of headaches and problems on the M57.

Of course, there are delete components available for those who want maximum performance and reliability from the M57, but that requires taking that particular vehicle off the road due to emissions. wink

Outside the emissions systems, the only real weak point you’ll find on the M57 is the flappers in the intake manifold. Each port is equipped with a plastic flap that’s supposed to improve fuel efficiency, but because it’s plastic, it will degrade with time.

When this happens, you can see large plastic chunks enter the engine, and rather obviously that’s going to cause some issues.

The ideal scenario is to delete these plastic flaps before they become a problem, especially if you’re in pursuit of performance, as increased boost pressure and heat can accelerate the timetable of which the plastic degrades and eventually explodes.

Why the 335D is Better Than the 335i

And that brings us to the platform and the applications, and more specifically, why the 335D could be a better option than the 335i for many buyers. Just think about it for a second. The N54 is well known for being a problematic engine, while the M57 is quite a bit more reliable.

The improved reliability paired with insanely good fuel mileage upwards of 40mpg if you have a light foot and the massive amounts of torque make the 335d a very attractive option.

Sure, you might not get the raw performance you could from an N54, but it’s pretty close. Unfortunately, the one downside with the 335D is that it was never offered with a dual-clutch transmission like select 335i N54 models and N55 models.

The ZF6 transmission in the 335d certainly isn’t bad in any way. In fact, it’s quite capable of withstanding big amounts of power, but the slow upshifts and even slower downshifts leave much to be desired compared to the 7-speed DCT.

Of course, that opinion will vary greatly depending on who you ask, but regardless of the transmission, it’s hard to argue with the idea that the 335d is a great alternative to the 335i.

With some modifications and tuning, you can easily get a 335D into 12-second or lower territory, making it a pretty quick little street car with even more impressive fuel mileage.


So, while the US majorly lacks on the diesel car front as compared to many other countries, the BMW M57 is a glimpse of what we could have if we adopted diesel cars.

The performance is great, the tunability is nearly on par with the N54, the reliability is superb, especially for a BMW product, and the efficiency blows BMW gas engines out of the water.

In the US, we almost exclusively see diesel engines used in heavy-duty applications like Ram trucks, GM trucks, Ford trucks, and so on.

While the M57 is vastly different than many of those engines, it certainly deserves more recognition as a well-designed and powerful little engine that represents what German diesel engines are capable of as compared to American diesel engines.

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