Report: Bored Mercedes Engineers Drop Modern 250 CDI Diesel into 190 E Chassis


While in their down time the boys over at AMG might try and stuff a a 6.2-liter V8 in a SMART car, a particular group of diesel-crazy engineers at Mercedes decided to fit a modern diesel engine into a classic 190 E chassis from 1990.

Not quite as exciting, we know, but interesting none the less.

The donor car was a 190 E, made famous by its motorsports cousin. As for the engine, it is the very same diesel you’d find under the hood of a modern C250 CDI BlueEFFICIENCY. Back in 1990, Mercedes did make a 190 D, but this 190 D BlueEFFICIENCY makes for an interesting comparison.

While the old car made 132hp, the new diesel makes 204hp. The real difference, however, comes in the torque department. Whereas the old diesel made 181 ft-lbs, this new diesel motor pumps out an impressive 369 ft-lbs from just 1600 rpm.

And despite all this power increase fuel-consumption has been improved significantly as well. While the old 190 D’s fuel economy rating of 32 mpg was impressive at the time, this new 190 D gets a much-improved 48 mpg.



Official release after the jump:

The Mercedes 190 D BlueEFFICIENCY experimental vehicle

Back to the future: Baby-Benz with an up-to-date C-Class diesel engine

•    Driving enjoyment: almost three times the output of a 190 D •    Economy: considerably more frugal fuel consumption •    Protection: many more safety and comfort features today •    What if? Practical implementation of a theoretical discussion

From the outside it looks just like a more than 20 year-old Mercedes 190, tens of thousands of well-preserved examples of which can still be seen on Germany’s roads. Pressing the accelerator tells a different story: equipped with the ultra-modern OM 651 common-rail engine developing 150 kW / 204 hp, the Mercedes 190 D BlueEFFICIENCY shows the full potential of this new four-cylinder diesel engine. With a maximum torque of 500 Nm between 1600 and 1800 rpm, this experimental car has more than twice the torque of the most powerful model in the old W 201-series. The 190 E 2.5-16 Evolution II, which was presented in 1990 and produced 502 times as a homologation model for the Group A DTM touring cars, “only” manages 245 Nm.

The idea for this unusual experimental vehicle came about during an evening discussion about the enormous developments in diesel technology over the last 20 years. The question was: “How might one make this progress directly tangible, in isolation from the equally profound changes in the safety and comfort of the car as a whole?” The result was a factory-tuned car of a different kind: the 190 D BlueEFFICIENCY. It accelerates from 0 to 100 km/h in 6.2 seconds. It therefore manages this standard sprint 11.9 seconds faster than a 190 D of the time, which caused a sensation on its 1983 introduction with its newly developed, fully encapsulated “whisper-diesel”.

The differences between the two diesel generations are even more impressive when it comes to fuel consumption: despite the significant increase in output by 72 hp (OM 601, 1988) to 204 hp (OM 651, 2009), the new engine in the old body consumes 4.9 litres per 100 kilometres (NEDC) instead of the 7.3 litre figure 
for 1988.

But what is really astonishing is that measured according to the DIN standard 
used during the time of the 190 D, the Euro-Mix consumption of the current C 250 CDI BlueEFFICIENCY is a mere 4.6 litres per 100 kilometres, and 5.1 litres per 100 kilometres according to the present NEDC method. This represents an improvement of around 30 percent – not to mention the exhaust emission levels.

The playing field is by no means level: a Mercedes 190 D is 385 kilograms lighter than a current C 250 CDI BlueEFFICIENCY, for example. In addition to more interior space – the current C-Class model is 16 centimetres longer, and around nine centimetres wider and higher than a 190 – this is due to the high standard of comfort and safety features.

As a genuine Mercedes, the model 190 was ahead of its time in terms of safety technology. Nonetheless, customers at the time enjoyed nothing like the extensive array of passive and active safety systems to be found as standard in the current C 250 CDI BlueEFFICIENCY. These include seven airbags, the adaptive AGILITY CONTROL suspension and numerous assistance systems such as ESP® and 
ADAPTIVE BRAKE. Comfort-enhancing features like the ergonomically exemplary, multi-adjustable seats or electrically adjustable and heated exterior mirrors also contribute to the higher weight.

A number of factors are responsible for the outstanding efficiency of the current C-Class. Aerodynamics is one of them: with a Cd figure of 0.34 the 190 set an 
example for its time. The new C-Class betters this figure by far, however, and is once again the trendsetter in this segment with a Cd figure of 0.27. The progress is equally impressive where the powertrain is concerned: while the 190 D was 
equipped with a four- or optionally five speed manual transmission, the C 250 CDI has six gears available. Plus a large number of friction-reducing measures. The radiator fan, power steering and generator also operate much more efficiently than 20 years ago.


Generations in conflict

•    Chosen: the base vehicle was a 190 E 2.6 Sportline built in 1992 •    Borrowed: sump from the Sprinter, differential from the C-Class •    Tricked: electronics fool the engine into thinking it is in a test bench 

“No, I can’t say it was a real bargain”, says Peter Lehmann, reflecting on his purchase of the 190 E 2.6 which provided the basis for the unusual conversion. “After all, the W 201 has long since gained collector status, and this example dating from 1992 was in particularly good condition.” Lehmann knows a thing or two 
about the 190-series: as a Mercedes-Benz engineer responsible for the design and realisation of show cars and concept cars, and as the team leader for the conversion work, he privately owns no less than three 190s, ranging from the entry-level variant with its frugal 1.8-litre engine to the potent Evo model.

The small team that installed a new diesel power unit into the old 190 body within the space of a year also included two other, equally staunch fans of this model 
series. And they were not alone in their enthusiasm: “Almost every time the 190 was left in our workshop overnight, there was a note attached to it next morning asking if it was for sale”, says Lehmann. But it was not, and it has meanwhile 
become a priceless one-off example.

Packaging: what doesn’t fit is made to fit

The 190 E 2.6 selected for the conversion work was a good choice: its six-cylinder power unit weighs around the same as the modern OM 651, maintaining the weight balance between the front and rear axles. Moreover, the braking system 
of this former 160 hp model was already robust enough to keep very many more, modern diesel horsepower in check. As a Sportline version, this 190 also possessed a sporty, taut suspension setup which could be left unchanged. The usual day-to-day occupation of the conversion team was to look well into the automotive future with concept cars. This time it was a matter of resolving the past, however. The first challenge was that no CAD data existed for the 190. As used to be the practice, drawings of the engine compartment and engine were therefore transferred to see-through paper, then superimposed. As everything seemed to fit reasonably well, the body dimensions were accurately measured. The resulting figures were reconciled with the engine data to identify any 
potential collision points.

And packaging problems there certainly were. The steering would have passed straight through the sump, for example. A solution was found by consulting colleagues in the commercial vehicle sector: the sump of the Mercedes-Benz Sprinter was a good fit. The Sprinter is incidentally a distant relative, for the van is also available with the modern OM 651 four-cylinder common-rail diesel engine.

The adaptation work did not end there, however. The transmission tunnel of the 190 had to be widened to accommodate the current six-speed transmission, and 
in the case of the rear axle differential the team had recourse to the replacement parts range: the differential of the 3.2-litre W 203, i.e. the predecessor to the 
current C-Class, proved suitable.

Electronics: if it does not exist, it is simulated

“The greatest challenge during this project was not in fact the hardware, but 
rather the electronics”, says Peter Lehmann. This because the 190 did not yet have a CAN-bus as a data transfer system. In the current C-Class with its state-
of-the-art OM 651 engine, more than one dozen control units are in constant 
communication with each other to coordinate their respective tasks. The car will not start without the right signals, as the electronic ignition lock acts as a link 
between the engine CAN-bus and the interior CAN-bus.

So the team creating the 190 D BlueEFFICIENCY came up with a clever idea: they fooled the engine into thinking it was on a test bench. The appropriate signals are sent by a box of electronics roughly the size of two shoe-boxes in the boot. This is what enabled the OM 651 to spring to life, and it performs its duties with the 
usual quietness and refinement under the bonnet of the W 201.

But the next problem was not long in coming: for the car to operate as it should, the electronics required ABS signals. Turning wheels cannot be duplicated even on a virtual test bench, however, so once again the electronics specialists were called for – and now the ABS signals are likewise simulated.

“The driving experience is really unique”, Lehmann enthuses. “The modern diesel is easily able to cope with the 190. This level of muscular torque was simply unimaginable at the time, likewise the amazingly low fuel consumption.”

There were other things beyond the wildest dreams of the engineers developing the W 201 at the end of the ’70s, for example the digital speedometer or four-channel ABS. “With its uncluttered design, the 190 appears timeless and drives very well indeed. Nonetheless the technical progress made in automobile engineering over the last three decades was our constant companion during the conversion work”, Lehmann concludes.


Jose de la Maza says:

Remarkable! These old Mercedes W221 and Mercedes W123 like 300E, were made to last and thousands of them are circulating all over the World.

Maybe it is not a good business for Mercedes but I wish they sell the OM 651 diesel engine as a separate kit (with all the electronics needed) as for be installed into these beauties.

Jose de la Maza says:

I want such an engine!

Please, sell one to me!