Review: Mercedes-Benz Actros 13-litre

Name: Review: Mercedes-Benz Actros 13-litre
Brand: Mercedes-Benz

The ‘baby’ of the Benz engine range punches well above its weight

Several years ago I conducted a series of back-to-back B-double road tests – same route, same payload, similar spec. The first was the junior of the bunch, in two ways. Firstly, it had a 13-litre engine while most of the trucks on the program had 15-plus litres. Secondly, it was a UD, not a brand known for interstate B-double work. With just 470hp I said at the time that it punched well above its weight, handling a series of long hills as if it had over 500hp.

Well, I’ve just driven the latest Mercedes-Benz ‘baby’ big-block 13-litre engine on a similar run, and it did the same. But this one performed the way it did because of the diesel engine development technology that has exploded over the past seven years.

Several key factors illustrate the advancement. It’s more powerful, by an extra 60 horsepower, develops 345Nm more torque, is at least three generations cleaner while using nearly ten per cent less fuel. Plus with advances in emission control specs and technologies, its AdBlue consumption is around a fifth of the UD’s. That’s the reason that the AdBlue tank is still just 60-litres, with a 110-litre version as an option.

The OM471 six-cylinder turbo-diesel is a dark horse in the Benz Actros range, and is rapidly gathering widespread credibility with fleet operators who feel that 16-litres is more horsepower, more weight, more fuel consumption, and more cost and maintenance than is really necessary for the task at hand.

So I took this latest truck for a run up the mountain eastwards from Adelaide to see how this engine and driveline handled a 62.5-tonne rig in average commercial conditions.

The 13-litre is available in two states of tune. There is a mild-mannered 510hp/2500Nm version for the 6x4 single-trailer regional prime mover role. It’s linked to the G281 12-speed PowerShift AMT with a dual plate clutch. The test truck was specced for B-double work and had the wick turned up to 530hp/3000Nm, and the same PowerShift unit, also with a dual clutch, but a taller final drive ratio – 2.733 instead of 2.846. That indicated to me it would pull about the same as the 510hp, but have longer legs on the cruise.

As I’d recently spent a full day in the big-bore 16-litre version on a run from Melbourne to Sydney, the fully-galvanised Actros cab and fit-out was no real surprise. What was new was the end of the matt black evaluation trucks that Daimler Trucks has run in field testing for the past 12-months or so. This drive was in the truck that is now on sale and ready for permanent work in a fleet.

The interior on these showroom-ready units is a successful blend of practical materials and comfort surfaces. Driving, resting and sleeping areas are different hues to help drivers adjust their roles.

Ergonomics on current Euro trucks barely deserve a mention, as they are all focused tightly on driver comfort and ease with the essential controls. The tilt/telescopic steering column and air seat can be adjusted to sit you forward for those inner-city manoeuvres, or slightly reclined for highway cruising. It’s clear that the local Benz people have had serious input into Germany regarding these cab features, as linehaul distances between stops in Australia are so much longer than they are on the autobahns.

Clever Technology

Some technical details on the new engine are worth noting here, particularly as the advancements will impact on the decision to buy less horsepower up front, in the hope that running costs will be lower, while hopefully losing nothing in longevity.

The engineers designed a package with the goal of increasing service life by around 20 per cent. Durability targets by component have been extended. Service intervals are nominally out to 80,000kms, although the actual figure will be calculated by the truck’s central electronic control unit and displayed on the information data screen. The program will assess fuel burn, torque demands, weight calculations and other factors to calculate the impact of usage and recommend servicing as it falls due.

There are new one-piece steel pistons instead of the aluminium units in the previous engines. Second generation X-pulse common-rail fuel injection operates at between 1160 and 2700 bar.

The engine features an in-house Mercedes-Benz designed asymmetric turbo, and peak torque now arrives at a very low 800rpm, running through to 1400rpm. Linked to advancements in the PowerShift 3 AMT transmission, the driveline generates up to 30 per cent more torque at start, meaning fewer shifts and longer clutch life. The PowerShift 3 itself is calibrated to deliver 20 per cent shorter shift times.

The sum of all that allows Mercedes-Benz to claim a full seven per cent fuel saving over the previous model. And of course less fuel means less emissions as well.

On the road
Behind the wheel, all this data – and I made sure I read it thoroughly before heading off – combined to make me pretty conscious of the technology at the beck and call of my right boot.

Usefully, the Actros won’t wake the neighbours when you leave early. Inside and outside, the engine is well muffled. On a steep section of the hillclimb I opened the passenger’s window to hear the truck sounding off against the stone embankment. There was no booming exhaust, just a steady rumble accompanied by continuous whistles and clicks from servos doing their job.

I repeated it going down the hill with the full exhaust brake on. This is one truck that allows you to ignore the signs that plead for restricted engine brake use.

The cruise control on the test Actros was the optional adaptive version, and I’ve become used to trusting the radar to do its job.

The three-stage engine brake was strong on full, but I think I’d opt for the retarder for regular B-double work. The brake works in conjunction with the cruise control and will help keep the over-run – and your license – under control. Importantly, when I manually engaged the engine brake, and even added some footbrake, the cruise control stayed engaged and took over when the speed returned to the set point.

The optional active brake assist defaults to ‘on’, and assures owners that rear-enders will be minimised.

Stability on the Actros is very good. The chassis is stiffer and helps the truck track well. The frame is wider and stronger – it’s out to 834mm now and 600-700MPA steel helps with rigidity. A new hypoid tandem axle and wider mounted four-bag suspension also contribute.

It seems like local Mercedes-Benz product planners have done all they can to set up a truck that will satisfy every concern of line-haul operators. Some will stay with a 16-litre, but the leaning is definitely towards saving some cash up front and some fuel down the road with this smaller 13-litre engine.

2016 Mercedes-Benz Actros Specifications:

Engine: 12.8-litre OM471 in-line six-cylinder

Power: 530hp

Torque: 2600Nm

Emissions: Euro VI

Std transmission: PowerShift 12-speed with dual plate clutch

Configuration: 6x4

GVM: 26,000kg

GCM: <70,000kg

Wheelbase: 3250mm

Brakes: All disc

Cabs: Half and full sleeper