Power war goes four-pot

Expect a 300kW-plus version of the A 45 after its senior engine development manager insisted yesterday there was “no way” Mercedes-Benz hotshop AMG would allow Volkswagen to take the lead in four-cylinder power.

It’s common knowledge that both Volkswagen and Audi are planning to deliver a 309 kW version of its 2.0-litre four-cylinder EA888 engine next year, which would leave the once-mighty AMG four-pot well behind.

The highest-spec versions of the AMG 2.0-litre four produce 265kW of power and 450Nm in the A 45 and CLA 45 AMGs, though the all-wheel drive cars' powertrain limitations reduce the engine’s torque output in its lower gears.

“We cannot, and will not, let them get ahead of us,” senior AMG Powertrain Development engineer Jochen Martin Schmid said yesterday.

“If that means the start of a new power war for four-cylinder cars, then it's the start of a new power war for four-cylinder cars.”

Schmid acknowledged the next step for AMG would be to hike the power and torque of the existing 2.0-litre engine and admitted it would need at least 310 kW to keep its nose ahead of the Volkswagen Group motor.

“Theirs is based on the EA888, right? That’s a pretty old engine now and ours is a completely new concept with room for development.”

While targeting a higher power number and a rise in torque from 450Nm to something closer to 500Nm, he said AMG wouldn’t chase higher revs from its four-pot, due to the extra stresses it would place on the valvetrain.

Instead, he hinted there would be changes to the exhaust system and a rise in boost from the twin-scroll turbocharger’s current maximum of 1.8 bar.

With up to 140 bar of peak pressure inside the engine, the AMG motor uses the mass production of parts normally considered the domain of racing cars, like sand-cast engine blocks, forged steel crankshafts, sand-cast aluminium crankcases and spray-guided direct fuel-injection. Schmid suggested these areas needed minimal work to cope with more than 300kW of power.

Any upgrade would most likely arrive in Evolution versions of both the A 45 and the CLA 45 models late next year, just ahead of the planned introduction of the high-po four-cylinder cars from Audi and Volkswagen.

It would also need to address its transmission limitations, which see it hitting 100km/h in 4.6 seconds when Audi is targeting a sub-four-second figure for its S3 Plus and Volkswagen is looking in the same region for its Golf R Plus.

If there is a four-cylinder power war (in which the AMG engine’s 133kW/litre isn’t enough), it will be a war largely of the making of one man: Friedrich Eichler.

The Volkswagen Group last year poached Eichler from his post as AMG’s head of engine development, to manage its petrol engine, transmission and hybrid development. Eichler led the development of the A 45 engine for AMG and, once he knew where the coffee machine was in Wolsburg, was immediately tasked with overhauling his own creation for Volkswagen and Audi.

So far, he’s convinced plenty of Volkswagen Group head honchos, with Audi’s engineering boss Dr Ulrich Hackenberg insisting there is nothing stopping the thumping 2.0-litre engine, fitted to the TT Quattro Sport Concept car, from reaching production.

While it has less torque than the AMG engine (with 420Nm compared to the 450Nm of the AMG), the EA888-based engine revs higher and has more than 200 horsepower per litre.

“It can go into production nearly how it is in the TT Quattro Sport Concept,” Dr Ulrich Hackenberg insisted at the Worthesee festival.

“For production, we have to change the cylinder-head, because in the EA888 it has the exhaust manifold in the cylinder-head now. With this engine and its output, it produces too much heat in the head to keep it like that, so we have to change it.

“But, apart from swapping in some stronger parts, it can still be made within our production system.”

The engine that has AMG seeing red(lines) has a relatively low claimed torque peak, arriving at 2400rpm and remaining until 6300rpm, though there is at least 300Nm available from 1900rpm.

The 150kg engine’s power peak arrives at 6700rpm, thanks to a combination of direct and indirect fuel-injection, variable valve timing and lift, plus a thumping big turbocharger.

But calling it an EA888 engine denies much of the work Eichler’s team has already done. Its extra punch demanded custom forged aluminium pistons with integrated cooling channels and an ultra-high strength crankshaft.

Most of the developments have been in the cylinder-head, where an almost-all new unit was designed to cope with the higher gas flows, while the crankcase is now made in high-strength cast alloy. Its turbocharger forces air into the engine at up to 1.8 bar of atmospheric pressure, all the way to its rev-limiter at 7200rpm.