Mercedes confirms 415bhp power output for hot A-Class, CLA and GLA, and we've got all the details of the new M139 unit

The world’s most powerful 2.0-litre, four-cylinder series production engine has been revealed by Mercedes-AMG, set to feature in its upcoming ‘45’ model range. 

Developing 415bhp in its most potent ‘S’ form, this completely new 2.0 turbo replaces the engine used in the previous A45 A-Class, CLA 45 and GLA 45.

Despite the potency of the outgoing A45 355/376bhp AMG four, engine development boss Ralf Illenberger says that emission requirements, the desire for more power, less weight and the different packaging requirements of Mercedes’ latest generation of compact cars necessitated a complete redesign. “The only carry-over parts are a few nuts and bolts,” he added. The new M139 engine produces 382bhp in standard form and 415bhp in ‘S’ guise, and 354lb ft or 369lb ft of torque.

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Another major aim has been extracting a sportier driving experience from the engine by altering its torque delivery. While the previous, M133 four-cylinder engine’s torque curve resembled a diesel’s, rising steeply to level off across a wide chunk of the rev range, the new M139 2.0 produces more of a crescendo of thrust.

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The aim is to produce the rising rush of acceleration characteristic of a revvy, normally aspirated engine. Rather than flat-lining, diesel-style, from around 2000rpm, AMG’s new engine generates peak torque at 5200rpm, while nevertheless producing more shove than the old one between 1000-2000rpm, the strongest surge developing from 3000rpm. Overall, said Illenberger, “it produces a more sporty delivery”.

More diesel-like are the 160 bar combustion pressures generated by the new unit, and a lighter yet more robust cylinder block developed to withstand them. It’s of the closed deck variety, creating a crankcase casting more like a part-closed box rather than a semi-open one, with deep, strengthening skirts around the cylinders. The new alloy block is as strong as a diesel engine’s, said Illenberger. The 16-valve cylinder head is also new, a key design challenge being the dispersal of the considerable heat generated.

Larger exhaust valves and valve seats, a redesigned water jacket, oil, water and air chilling for the turbo and separate coolant plumbing for the cylinder head and cylinder block allow more efficient and protective control of under-bonnet temperatures, assisted by electrically controlled water pumps. The head itself features ‘Camtronic’ variable inlet and exhaust valve control and dual injectors per cylinder.

A single piezo-injector per cylinder would be at the upper limit of its fuel volume delivery, said Illenberger, so a second quartet of injectors sits within the inlet manifold tracts to boost delivery under hard acceleration. The Camtronic system enables two camshaft profiles to provide a blend of good fuel economy and heightened throttle response.

The vanes of a sizeable turbocharger run in low-friction roller bearings, an electric wastegate minimising the loss of boost when pressure modulation is required. The turbo now lives between the engine and the front bulkhead, the cylinder head having been turned through 180deg in order to fit the engine beneath the lower bonnet lines of the new models.

The turbo’s new location requires extra cooling, some of this provided by an engine cover shaped to direct fan-generated airflow over it. Illenberger said that the electric water pumps may also function after the engine has been switched off, to cool the block, head and turbo. The more potent ‘S’ version sometimes harnesses the air conditioner for cooling too.

Besides designing an all-new engine, AMG has also developed a more streamlined way to make it. Each engine is still built under the ‘one man, one engine’ approach long used by the company (there are several women hand-assembling these engines too, incidentally) – the methods of electronically recording the sequence of component assembly, and the torque applied to each of its fixings, by each power tool. The new methods save time and improve ergonomics.

The new methods cut the production time by 20-25%, said plant manager Alexander Kurz, enabling AMG’s four-cylinder manufacturing facility to produce 140 engines per day over two shifts. The first car to feature this unit will be the A45 in July, the CLA 45 saloon appearing near-simultaneously, the GLA 45 a little later.

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Comments
21

7 June 2019

Can't help but feel happy about this article and I am not an AMG fanboy as some may know.

7 June 2019
In 2016 the a45 engine was upgraded to 381 bhp this upgrade was carried over to cla45 and gla45

7 June 2019

381 metric horsepower = 376 BHP. The EU mandate metric british car mags use traditional so you are both correct.

jer

7 June 2019

And is this the new 4.0 v8 with 820bhp ?

7 June 2019
jer wrote:

And is this the new 4.0 v8 with 820bhp ?

 

imagine then adding in a electric motors too.. taking it easily close 1000bhp.. brilliant !!

7 June 2019
jer wrote:

And is this the new 4.0 v8 with 820bhp ?

 

I predict V8 will disappear. Especially with the Swedish MSc Finance CEO at the helm of MB.

7 June 2019
NoPasaran wrote:

jer wrote:

And is this the new 4.0 v8 with 820bhp ?

 

I predict V8 will disappear. Especially with the Swedish MSc Finance CEO at the helm of MB.

415bhp, isn’t that enough?, in day to day driving how often could you use the performance the car is endowed with?,if your driving faster than that you’ve been lucky not to get caught, 800, 1000+ BHP are just Trackday hacks, they’re costly to run and or fix if crashed, at least at the price point of this Merc isn’t going to eat a large hole in your pocket, no, this is the zenith of Engine capacity, could pose an end to anything bigger than six cylinders, Ev power will contribute to the demise of ICE cars to.

Peter Cavellini.

7 June 2019

Why not a V12, or a W16, or five banks like certain WW2 American tanks? Actually the tanks were made from straight-six civilian car engines, so 30 cylinders in total!

7 June 2019

With the systems being engineered to save the engine from cooking,what will AMG do for very hot countries in the summer,Spain for example.Remember the Jag XJS V12.You could BBQ a steak on the engine when it  repeatedly over heated.

I also assume AMG won't be giving a 7 year warranty in the near future for this and other very "hot" engines.

I would still like one though.

garage man

7 June 2019

So u think AMG and Mercedes engineered an engine to catch fire??

the article just mentions that they had to take a different approach to cooling for the new engine.. waffle for sake of waffle 

also jaguar engineering quality and reliability back in day wasn’t exactly renowned was it!! So stupid comparison a modern engine compared to something over 2 -3 decades old 

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