#Chip tuning for BMW Diesel

28 / September 2021
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Chip tuning for BMW Diesel

Seletron Performance

How to tune a BMW Diesel engine

Here is another car manufacturer that has contributed a lot to the success of diesel, especially in the first half of the 90s. We could talk about this German brand for hours, even days, without going through its whole history, its diesel engines, its turbocharging systems, the processing of BMW, etc. In short, it is an inexhaustible topic, but let's try to identify at least some salient points of interest for fans of diesel tuning and fans of 4 wheels in general.

BMW's first performance diesel engines

If we want to talk about the first major electronic innovations and the first high-performance diesel engines from BMW, we must surely talk about the little jewel (for the time, since we are talking about the 90s) 6-cylinder tds. A refined in-line hexa-cylinder mounted longitudinally on the 3 Series, 5 Series, and 7 Series. The engine has a displacement of 2.5 liters, 2 valves per cylinder driven by an overhead camshaft, turbocharger with waste-gate valve for boost pressure control, air-to-air intercooler, electronically controlled EGR exhaust gas recirculation, Bosch indirect injection pump with 6 outlets and electronic control of fuel delivery and injection phase, electronically controlled pneumatic engine mounts, Bosch EDC control unit with air temperature, diesel temperature, engine temperature, turbo pressure, engine speed, engine phase, accelerator pedal position, EGR control, engine mount control, and injection feedback on 1 instrumented injector.

It represents the mechanical and electronic fine-tuning of an engine that at the time was the most powerful 2500 turbo diesel indirect injection on the market, with 143 hp and 280 Nm of maximum torque. This engine was known for some peculiarities, as it was very quiet, it didn't vibrate, and was lazy at low speeds but had a great propensity to stretch at higher speeds. This engine had a limiter at 5200 rpm where, once the dead zone of low revolutions was reached, the speed rose quickly to the red zone without uncertainty and without that annoying sharp delivery that many turbodiesels had ( and still have) with great maximum torque but poor throttle when heading towards the red zone of the rev counter.

In some ways, the BMW tds doesn't seem like a diesel feels like a very pleasant-to-drive petrol. In the 90s, the 525tds equipped with this engine represented a benchmark for the category. It struggled with direct competition, specifically with Mercedes (with its 2500 with indirect injection 5 cylinders and 150hp) and with the excellent Audi A6 2.5TDI V6 (150hp and a brand new direct-injection system with radial piston pump). The 3 luxury sedans were compared by Quattroruote (and Italian car magazine), and the comparison highlighted that the 525tds, although with less horsepower, has the record for 0-100 acceleration with a time of 10 seconds.

Moreover, the Mercedes engine has 4 valves per cylinder, while the Audi one, in addition to the 4 valves per cylinder, also has a more modern direct diesel injection system. With similar technology but different phasing, there is also the 318tds that mounts a 1665cc with 90hp and 190Nm of maximum torque. This 4-cylinder also has some records in terms of specific power. The 2500 tds is certainly one of the engines that has attracted many drivers skeptical about diesel performance and soon became an engine that sparked the attention of tuners, who have developed tuning methods of varying interest, bringing its power to over 200 hp.

The advent of the BMW common-rail

In '98, however, something revolutionary happened: BMW unveiled the 5 Series (and other models) that featured the world's most powerful 3-liter turbocharged inline-6-cylinder series diesel. It was made with a unit displacement of about 500cc (the engine is a 2926cc), 4 valves per cylinder, a new variable geometry turbocharger (VNT), and, above all, a brand new Bosch common-rail injection system with 6 electro-injectors (which Fiat already used).

The power of the 530d E39 is an impressive 184 hp with an unprecedented 390 Nm of torque. The 530d completes the 0-100 km/h in just 8 seconds and reaches a top speed of 225 km/h. Shortly after, the power was increased to 193hp, and torque exceeded 400Nm. This was when AUDI returned to the ring, retiring the 2500 V6 and creating the 3.0TDI V6 common-rail, but we will talk about this another time.

Almost at the same time, BMW abandoned the direct injection system with radial piston pump ( the same technology used by AUDI in its V6 2500TDI) that it was using on the 2 liters 16 valves with 136hp and started to use the common-rail also on the 4 cylinders 2000d with 150hp maximum power initially. Needless to say, even the 3000d common-rail BMWs become very interesting for tuners, and our BMW chip tuning additional units could (and still can, since they are still available) generate strong increases in power and torque of up to 40hp and 80Nm!

BMW's exclusive supercharger system

The turbocharger is like a too-small blanket; if you want to be covered up to your head, your feet are left cold, and if you want to cover your feet, your head is left out! If the turbocharger is small, it is very quick and provides a lot of thrust at low revolutions, but it limits the lengthening and, therefore, the maximum power; but if the turbocharger is big, it provides a lot of power, but it has a severe turbo-lag, and at low revolutions, it is nearly inexistent.

So what did BMW do first on its already excellent 6 cylinders turbo diesel? It installed 2 turbochargers, but not a normal bi-turbo system with 2 identical units (a very good solution), so they went further and installed both a small and a big turbocharger! A complex system of valves and an accurate electronic control manage the hot flows and the flows of the 2 compressors to make the small turbocharger work at low rpm (high torque and very little turbo lag) and intermediate rpm, and the larger turbocharger at high rpm (high power).

The result? A 3-liter bi-turbo sequential (initially the 535d and 335d), embarrassing perhaps for other car manufacturers, as it has the impressive maximum power of 272 horsepower and a truck-like torque of 560Nm. This came first on the BMW E60 and E61, but shortly thereafter, the values were already adjusted to 286hp and 580Nm, absurd values for a 2000s mass-produced turbodiesel. Many drivers with sports cars must be afraid of being outclassed by a 3 Series or a 5 Series with the initials "35d"... don't believe us? Then you should know that the first 335d boasted a 0-100 acceleration in just 6.1 seconds with a top speed of 250Km/h. Today there are 3 liters BMW turbo diesel models with over 300 hp, but BMW had to go further and create the tri-turbo with 400 horsepower and 760Nm torque... If you see a BMW with M550d on the back, stay clear... it runs on diesel but don't test its limits...


See how in a few minutes you can install the CHIPBOX in your BMW Diesel

BMW processing with chip tuning modules

Discussing all the BMW diesel engine advancements is too complicated... suffice it to say that the 2-liter 4-cylinder engines started with 136hp, and then, after switching to common-rail, they were offered with 150hp, 163hp, 177hp, 184hp, 190hp, 204hp, 224hp, etc., and the 6-cylinder 3-liters debuted with 184hp, then 193hp, 218hp, 231hp, 235hp, 245hp, 258hp, 272hp, 286hp, 300hp, 313hp, 381hp, and 400hp (not in any particular order, the latest versions use bi-stage or tri-stage supercharging). Then, over time, 6-cylinder 2500cc engines were added, along with 1600 common-rail engines, and then modern 3-cylinder engines. In short, the range of BMW engines is almost unlimited, and what they have in common (since the advent of the tds mentioned at the beginning of the article) is excellent performance and an excellent propensity for electronic tuning.

Over the last 20 years, we have developed excellent chip tuning modules for all injection systems used by BMW, first with our VP37 digital chip tuners, then with VP44 digital chip tuners for the radial piston injection pumps used on the 2 liters 136 hp engines, then with the most modern and refined chip tuning additional units to increase the torque and power of BMW engines built from ' 98 till now.

The great advantages of the common-rail injection system have spilled over into the world of electronic tuning, and our chip tuning additional units can be installed with great ease on modern BMW diesels. In fact, it is sufficient to hook up some connectors that are very similar to those already present on the engine wiring harness. No modifications are needed, there is no need to open or tamper with the ECU engine control unit via software, and no wires are cut.

This is a very effective electronic tuning that is not invasive at all and is completely reversible. Everything can be unhooked to bring the BMW back to stock performance. The increases in torque and power are very influential on the performance of the car, especially in acceleration, recovery, and climbing slopes. Our BMW enhancement kits have always been produced in Italy, with top-quality components and technology, and our customers are distributed throughout the world. Our customers are extremely discerning drivers who have chosen a BMW because they want to strive for the highest levels even when they decide to tune their engines.

If you are also looking to increase the power and torque of your BMW, look through our catalog to find your specific model!


Chiptuning for BMW Diesel