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Review: A Farewell To AMG?s Atmo V8 Photo:
 
 
Tony O'Kane | Mar, 14 2014 | 2 Comments

Who would say no to the chance to put two thundering Mercedes-Benz AMGs back-to-back on the Albert Park GP circuit during Formula One week? (Not us... thought about it for a nano-second, pulled on the driving boots.)

One, the C 63 AMG Edition 507, and two, its turbocharged bigger brother, the E 63 AMG S.

But there was more significance to this than meets the eye. And it has to do with a big shift going on at the hi-po end of engine technologies.

This Sunday, the front straight at Albert Park will explode with the sound of turbocharged V6 engines - the first time turbochargers have been on a Formula One grid since 1988.

And as last season’s 2.4 litre naturally-aspirated V8s pass the baton to the new generation of 1.5 litre turbo V6s in Formula One, there are similar developments happening in the realm of road cars.

Turbocharging is making a big comeback. The reason? Manufacturers are trying to keep outputs high while simultaneously reducing CO2 emissions and fuel consumption.

BMW’s M car range - once the domain of high-revving inline sixes, V8s and V10s - is now turbo-only.

Audi’s last remaining atmo performance cars are the RS 4 and RS 5, and Mercedes-Benz’s AMG division is in a similar boat.

Right now all AMG products bar the C 63 AMG, SLS AMG and SLK 55 AMG sport turbochargers in their engine bays, and the end is near for the naturally-aspirated V8 Benz.

The M156 - AMG’s once-ubiquitous 6.2 litre naturally-aspirated V8 - has its neck firmly on the chopping block, and the next-gen C 63 AMG (yes, the name will remain unchanged) is expected to be powered by a 4.0 litre twin-turbo V8.

That engine will also power a new sub-SLS model to be dubbed the GT AMG, and a detuned version could very well find its way into the SLK 55 AMG.

Meanwhile the SLS AMG’s future is certain: production is slated to end in the middle of this year. Long story short, turbos are taking over at AMG.

But what is it about the 'Atmo v Turbo' debate that gets some of us riled up? If turbochargers are able to make more power with less thirst, why fight it?

To illustrate the differences between turbocharged and naturally-aspirated engines, we figured a quick comparison between the two technologies would be helpful.

Mercedes-Benz was kind to point us to the track and flick us the keys to the C 63 AMG Edition 507 and the E 63 AMG S.

The C 63 AMG is a lot of everything that makes the blood run hotter, and the Edition 507 even more so. Managing Editor Tim O’Brien raved about it when he reviewed the ‘507 last year, and it’s not hard to understand why.

Big V8, small footprint, pointy front end and a playful rear end make the Edition 507 a hell of a performance car, as well as a fitting send-off for Benz’s naturally aspirated V8.

And the ‘507’s V8, by the way, is pretty special.

Though based on the venerable M156, it borrows the crankshaft, lightweight conrods and forged pistons of the SLS AMG’s M159 6.2 litre V8 and makes 37kW more than a garden-variety C 63 for a total of 373kW - or 507 metric horsepower. Torque peaks at 610Nm.

But it’s not just about outright numbers. It’s about HOW the engine produces that power.

In the Edition 507’s hybrid M156/M159 engine, the power delivery is impressively linear. And it’s that linearity, that progressive swell of power and torque that enables the driver to easily modulate the amount of grunt that goes to the wheels.

And that’s exactly what you want when whipping around a course like Albert Park.

A progressive power delivery makes the car more predictable at low to medium revs, and the absence of any kind of turbo lag means throttle response is ultra-crisp.

It’s a powerhouse. Three-quarters down the length of Albert Park’s front straight we glanced down and saw “240” swing under the speedo’s needle, and there was still plenty more distance to travel before the braking marker.

And then there’s the sound.

As far as German V8s are concerned, the Edition 507 emits a full-blooded bellow that easily out-shouts the RS 4’s 4.2 litre V8 and outgoing E90 M3’s 4.0 litre.

It’s loud and hard-edged, and punctuated by a gutteral gargle on every upshift.

But this is probably the last time the 6.2 litre’s hard-edged bark will bounce off the concrete barriers at Albert Park. To take a glimpse at what the future holds we took a spin in AMG’s latest force-fed performance car, the E 63 AMG S.

Don’t be fooled by the badge. There’s no 6.2 litre V8 under the E 63’s bonnet (if you’re wondering why AMG uses a ‘63’ rather than the more accurate ‘62’ in its nomenclature, it’s a homage to the 6.3 litre M100 Benz V8).

Instead the E 63 AMG S uses a 5.5 litre twin-turbo bent-eight with 430kW of power and a mighty 800Nm of torque. It’s a monstrous engine.

And all of that extra urge is plainly evident as the accelerator gets tramped. After the briefest pause as the turbos spool, the E 63 launches like a rocket.

There’s no linear build-up of power like there is in the C 63, it’s just a constant wave of torque that pushes you onward.

And the E 63 AMG is all about massive midrange grunt. There’s never a point in the rev range where there’s a shortage of twist, and there’s no need to wind on huge revs to get anywhere quickly.

That’s not to say it’s a relaxed engine. Not at all, for the E 63’s ability to break traction at virtually any RPM means it can be just as manic as the C 63.

However the redline tells the full story. While the C 63 has its fuel-cut set for 7200rpm, AMG sees no need for the E 63 to spin past 6500rpm. Turbo torque simply negates the need for big revs.

But it does mean that different techniques need to be employed when driving fast.

While the C 63 AMG Edition 507 pulls cleanly out of corners and can be easily balanced with the throttle, the E 63 AMG S with its big midrange torque requires a more delicate touch.

Be a tad too heavy on the throttle at corner exit, and the rear wheels start to slip as the turbos start forcing more air into the engine.

With stability control on, that results in the ECU cutting fuel and frustratingly slow progress through the apex.

Turbocharged engines require a more delicate touch, as well as familiarity with how the engine delivers its power and torque.

The naturally-aspirated C 63’s 6.2 litre, on the other hand, is far more predictable.

Yet there’s no escaping progress, especially when legislators are breathing down the necks of automakers everywhere, demanding lower emissions.

And a glance at the spec sheet confirms exactly why the likes of AMG, M, and Quattro are trotting down the turbo path. .

The C 63 AMG Edition 507, in all its naturally-aspirated glory, consumes an average of 12 l/100km on the combined cycle. The E 63 AMG S, though boasting 57 more kilowatts and 190Nm more torque, needs just 10 l/100km.

And that’s not all. The E 63 sprints to 100km/h 0.1 seconds faster than the ‘507, despite being nearly 200kg heavier. Turbos clearly do more with less.

But there’s no beating the raw, unadulterated feeling of a naturally aspirated engine. Especially one as big and brawny as AMG’s M156.

If you’re a Benz aficionado and have the dollars, buy a C 63 Edition 507 while you still can. It represents the end of an era, and when it’s gone we shall miss it dearly.

 
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