High powered Mack is back

Since the demise of the iconic V8 Mack engine in the 1990s, the top end of the Mack truck range has had to depend on vendor engines to get the kind of high horsepower required in the applications for which they are designed. Now, with the introduction of the MP 10 SCR engine in the Superliner and Titan models, there is a big banger with 600 or 685hp on tap under the bonnet with the Mack name on it.

And, it has been a long time coming. The 16L Mack engine has been available in the US market for quite a while. However, the requirements of the Australian market, especially at the heavy end, are very different from those needed by the vocational and linehaul operators in the US. It was vital for the Mack organisation here in Australia to be able to bring in a genuine top power engine.

The development program needed to achieve the kind of levels of power and torque the trucking industry expects to have available when working at high GCM. Volvo had managed to wring 700hp out of the same basic 16L block, and Mack needed to find a way to get similar power and torque levels in a North American style engine.

The result is a clean design with plenty of power available without the need for a massively increased cooling package. By forgoing an EGR emissions control system, Mack has managed to fit a big engine into the existing truck envelope with little disruption to the original design. At the same time, the integrated driveline offers AMT transmission and driveline protection at the top end of the GCM scale.

Prime Mover took a couple of the new models out on the highway from Adelaide to Port Augusta and back, in South Australia. Hauling two trailers at top weight gives this driver a chance to really assess what is available under the bonnet and how well it performs in real world conditions.

The truck itself looks little changed, both the new Titan and the new Superliner are basically the same as their ‘New Breed’ predecessors. All of the changes are under the bonnet and out of sight. Apart from the prominent MP 10 badge on the bonnet with the number 685 proudly displayed, the only giveaway there is something different going on, is the controller for the mDrive gearbox.

The trucks to be tested both use the 685hp rated MP 10 as a power plant. This means they must be fitted with the Mack mDrive transmission as this is the only one available and able to cope with the torque coming down the driveline. The engine puts out 685hp (515kW) between 1550 and 1800rpm coupled with 3150Nm (2300 ft lb) of torque from 1000 to 1550rpm.

Choose the 600hp option and other transmission options become available – the Mack 18 speed manual and the 18 speed Roadranger. Although untested here, the 600hp option of the MP 10 should prove to be a viable alternative to the Cummins ISX. Apart from putting out 2800Nm (2065 ft lb) of torque between 1000 and 1500rpm, the top power rating at 600 is available from 1552 to 1900rpm. All of this power and torque is available in an engine which does not use EGR and will therefore put less strain on the cooling package when working hard. The only thing missing is the familiar ‘kick in the pants’ feeling for the driver as the Cummins’ torque rise hits home.

The power and torque available is clearly evident when setting off with two trailers loaded to around 80 tonnes. The torque comes through steadily, building momentum as it goes. The effortless way the engine goes up through the gears is reminiscent of the way the two Scandinavian 700hp plus engines perform when integrated with a proprietary AMT. It is clear that the engine is working hard as the combination accelerates at the kind of speed expected in a top power B-double.

Gear changing is extremely smooth as the transmission uses the data from the engine and driveline to choose just the right moment to change ratios. The choice of when and how to make changes is much improved when compared to the AMT option available in the previous model. The combination of the very torquey ISX and the clunky Autoshift does not come up with the kind of intuitive changes seen here, although the newer Ultrashift Plus will be able to get the changing regime much closer to the performance available from the Mack driveline.

The engine note, and the response to the right foot, that the driver gets from the MP 10 does confirm its North American heritage. These engines are made in the Hagerstown facility in Maryland USA and the engine mapping has been developed specifically for North American tastes. The responsiveness can also be put down to the lack of an EGR system on this engine. Engines using just SCR to control emissions without recirculating exhaust gases do tend to feel a little more free running and responsive.

Getting the combination out of Adelaide is relatively simple and the flexibility of the driveline means the double road train can keep up with the general flow of traffic around it. Revs rarely move outside of the 1000 to 1500 range, where the engine is at its most economical. For what is, essentially, a road train prime mover, the Titan has relatively good all-round visibility in high traffic situations. The front bonnet slope means it is unlikely a driver will lose a small vehicle from sight in front of the truck for long.

Out on the highway, heading north towards Port Augusta, the truck comes into its own. This is its natural environment, in open, relatively flat country pulling a couple of trailers at 80 tonnes. The power and torque mean it is easy to keep the combination at highway speed, 90km/h on this particular section.

The ride is both smooth and consistent, making it easy to keep the whole combination straight and within the white lines. The model tested uses a Mack FXL 18 with 52 inch multi-leaf springs plus a pair of Meritor RT 52-185 drive axles running with a ratio of 4.30:1. The rear suspension is a Neway AD 260 heavy duty air suspension.

The rest of the specifications are typical for a road train prime mover with a 52 inch high rise sleeping compartment. 1950L of diesel in four D-shaped tanks is supplemented with a 150L Adblue tank. The SCR unit is fitted to the chassis between the two fuel tanks on the driver's side, limiting the available space for further fuel storage.

When called on to dig in as the occasional climb up a grade comes into view, the MP 10 does not shirk its responsibility. Even when faced with relatively sharp climbing, the mDrive transmission was unlikely to stray far from the top of the box. Occasionally the work made the truck grab a couple of gears and drop to tenth to maintain momentum over the rise but this was done smoothly with little fuss.

Because the transmission and engine are so closely integrated, the transmission always knows just how much torque is available as well as how much is required at the road. This means it will hold gears a lot longer than the average truck driver would feel comfortable with. The first instinct is to grab a gear or two at the foot of the incline to ensure revs remain high throughout the climb. The mDrive does no such thing, it may grab a single gear as it assesses the grade using the inclinometer in the transmission but is very likely to hold onto a gear as the truck approaches the crest, allowing the truck to smoothly go over the top at just over 1000rpm.

This can be somewhat unnerving for a more traditional truck driver but allowing the control systems to make decisions about the combination of engine and transmission does pay dividends, in terms of both fuel economy and ease of use for the driver. There are certainly times and conditions with which this system cannot cope. Intervention by the driver is simple as the mDrive control pad is close to the left-hand. However, the need for such intervention would appear to be much lower than many drivers often think.

The Mack organisation here in Australia will be delighted with the arrival of this new truck. The company finally has something that is capable of putting it in the driving seat at the top end of the heavy duty truck market. In the past, the Mack brand dominated the road train and heavy haulage prime mover market. The Titan and Superliner fitted with the MP 10 now give them the most powerful conventional truck on the Australian market, by a long way.

‘There is no replacement for displacement’ used to be the catch cry used by North American engine makers and these new high horsepower Macks have power to burn. What has changed is the integration of European technology into a North American truck and North American driveline. Now it has been possible to turn the wick up on a 16.1L engine to 685hp because the transmission has been designed to cope with the power and torque as it comes through.

There will clearly be naysayers who somehow think U.S. horsepower is of a better quality than the European horsepower. However, this is a North American engine, albeit with some European heritage, and it does have a strong Australian heritage. Mack has been a major part of the heavy duty truck market for a long time in Australia and coming up with these trucks looks set to continue that tradition. Mack buyers in the past were used to a one stop shop for the heavy duty prime movers with Mack branding throughout. It seems the Mack big banger is back.

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