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

The West Australian - - WEST WHEELS | NEWS -

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.

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