Merc-AMG’s mind-blowing mission
SAM JEREMIC heads to Germany to check out the new A 45’s engine that eclipses its predecessor and rivals
When the MercedesBenz A 45 AMG landed in Australia in 2013, it blew everyone away.
Here was a scorching hot hatch armed with a 2.0-litre four-cylinder turbo-petrol engine packing an unheard of — at the time — 265kW and 450Nm.
However, the ensuing years have seen the hot hatch game taken to another level. Audi revealed the RS3 with 270kW, before Mercedes countered by boosting the A 45 to 280kW.
Audi then predictably responded with 294kW — though the RS3’s engine does have an extra 500cc and a fifth cylinder at its disposal.
So when Mercedes-AMG announced details of the upcoming all-new A 45’s M139 powertrain in Affalterbach, Germany, the numbers were understandably bonkers; AMG head of engine development Ralph Illenberger admitted he had a figure of 420hp (309kW) as his dream outcome.
Well, he got there, with the
new engine offering a staggering 310kW and 500Nm in the top-spec S version.
There is also a lower version, offering “only” 285kW, though we’re unlikely to get it in Australia.
With the car still undergoing homologation and testing, details such as the 0-100km/h time is yet to be revealed (we’ll go out on a limb and predict it will something blistering fast).
Fuel consumption is also still to be determined but Mr Illenberger said the new unit was more efficient than the outgoing M133 engine.
In fact, Mr Illenberger said a big emphasis was placed on everyday drivability, with the engineering team looking to create an engine which behaves as close to a naturally aspirated unit as possible.
This involved a process Mr Illenberger dubbed “torque shaping”.
Typically, a torque graph line looks long and flat: max torque arrives early in the rev range, lasts for a few hundred or thousand rpm, before dropping off again.
The M139 sees more than 400Nm available before 2000rpm, before then increasing again at higher revs to see max torque arrive at a high 5000-5250rpm.
Engineers think this will result in a “more emotive driving experience”.
Once again, the A 45 will be all-wheel-drive, however this time around it will have an eight-speed automatic rather than a seven-speed.
Of course, packing all that performance in a 2.0-litre turbo four-pot isn’t easy.
Mr Illenberger said it was clear early on the team would have to create an all-new engine to get the outputs they wanted; nearly no components from the M133 were carried over.
The team rotated the engine 180 degrees, moving the turbo to be at the rear and allowing for the car to have a flatter nose and better weight distribution.
Cooling was a major issue — especially for the twinscroll turbocharger, which offers 2.1 bar boost — with oil, water and air all used to keep things from overheating. The car’s air-conditioning system even helps out. There is a chill-cast aluminium crankcase to handle the extreme pressure, with Mr Illenberger stressing the engine will enjoy a long life span.
Now, we wait, impatiently, to see what this engine can do.
The current A 45 hot hatch is already insanely fast.
The AMG factory where the M139 engine is made.
The M139 engine.