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Everything we know tells us that trucks with large, powerful engines have poor fuel economy. Can Volvo’s FH16 750 prove that we don’t know everything?
The FH16 750 gives Volvo bragging rights to Europe’s most powerful production truck. That has very little relevance to most of us, but the marketing tussle between Volvo and arch rival Scania to claim the crown suggests that they, at least, regard it as a title worth holding. At the beginning of 2009 Volvo trumpeted that it had uprated the 16.1-litre engine in the FH16 to a top nominal rating of 700hp – Europe’s first 700hp truck. Scania responded in 2010 by increasing the swept volume of its big V8 from 15.6 litres to 16.4 litres, pushing up peak power to a nominal 730hp. Last year Volvo upped the ante once more by leapfrogging Scania with the 750hp FH16.
Choosing 700hp or so might seem justifiable for 60-tonne logging trucks in Sweden or Finland, but surely this amount of power is pure indulgence in the UK unless you are in heavy haulage? Only 84 trucks with more than 600hp were registered in the UK last year. Of those, only 41 had nominal ratings of 700hp or more. So, as we embarked on this test we fully expected the results to confirm what the market appears to be telling us: 750hp at 44 tonnes GCW makes no sense at all.
Technical profile
Volvo’s D16G engine is an in-line six with a swept volume of 16.1 litres. It is an overhead camshaft design, with Delphi unit injectors and a relatively simple fixed-geometry turbocharger. NOx reduction for Euro-5 and EEV emissions limits is by SCR exhaust after-treatment. Peak power output is 739hp, developed from 1,600rpm to 1,800rpm: the 750 badge reflects Volvo’s preference for PS power ratings rather than hp.
Arguably, the more impressive figure is the 3,550Nm of torque available from 1,050rpm to 1,400rpm. The average peak torque of 6x2 tractor units sold in the UK last year was just over 2,200Nm: this Goliath of an engine generates that at just 850rpm, little more than tickover.
This engine’s massive torque output determines the rest of the driveline. The usual way of getting the best fuel performance from a high-torque tractor unit is to use a gearbox with a direct-drive top ratio, paired with a tall rear-axle ratio. But when the engine is producing as much torque as this one, that puts massive loadings on the prop-shaft and the differential. So Volvo opts for an overdrive (0.78:1) top ratio in the 12-speed I-Shift automated gearbox, reducing torque in the driveline to more manageable proportions. Having increased the speed of the prop-shaft like this, a fairly short (3.40:1) final-drive ratio takes the speed back down at the rear axle. Volvo previously used a hub-reduction axle to limit drive-shaft torque loads on the FH16’s top power ratings, but the introduction last year of the RSS1360 single-reduction axle – a 13-tonne axle, good for gross vehicle weights of up to 60 tonnes – means these energy-sapping hub-reduction gears can be eliminated.
This gearing strategy means the FH16’s engine is turning at 1,215rpm in top gear at our motorway cruising limit of 85km/h (53mph). This is no lower than most conventional 44-tonners with 1,300Nm less torque, leaving us wondering if one of the four taller ratios available would prove more fuel-efficient. On the upside, 1,215rpm is right in the middle of the 1,050rpm-1,400rpm peak torque plateau, and you also have 600hp on tap at this point, providing a wonderful blend of flexibility and performance for the driver.
Drive-axle tyres are conventional 315/70R22.5 size but the test vehicle has wide single (385/55R22.5) tyres on the steering axle to preserve as much front axle payload capacity as possible, bearing in mind that the engine weighs around 200kg more than the typical 12-13-litre engine.
Buying a 6x2 FH16 is not for the cash-strapped, with list prices starting at £107,846. To bring it up to the 750hp rating will cost another £13,315. To match this test vehicle you need to tick the boxes for the Globetrotter XL cab plus the ‘1-bed+’ and ‘Driving+’ packages. The test vehicle also has a Volvo Engine Brake+, aluminium wheels, air kit and I-Shift gearbox with fuel-economy software. The bottom line is an eye-watering list price of £141,962 (plus VAT).
On the road
Launched in 2001 and now in its third guise, Volvo’s 12-speed I-Shift gearbox remains an excellent automated transmission. It changes gear in a heartbeat and is smart enough to get on with the job without undue interference from the driver. Over the years Volvo has developed a range of optional I-Shift software that allows operators to shape the transmission’s control strategy to their own duties and preferences.
Last year’s introduction of a single-reduction rear axle with sufficient torque capacity for the FH16 750 was undoubtedly good news. Volvo reckons that fuel consumption should be up to 2% better than with the previous hub-reduction axle, and from a driver’s perspective the truck seems to roll more freely without the extra set of gears in the hubs. This is particularly critical when I-Shift is in I-Roll mode (formerly known as Eco-Roll), freewheeling with the drive train disengaged and the engine at idle. On average, I-Roll saves another 2% of fuel, according to Volvo.
While I-Roll allowed us to waft down hills at a whisper, it was 3,550Nm of torque that propelled us up them almost as effortlessly. The FH16 hardly broke sweat during its two days and 760km with CM, despite running at the 44 tonnes limit. From joining the M6 at J12 west of Cannock to reaching Gretna at the end of the first day, it was top gear all the way. The combination of immense torque and that flexible gearing mentioned earlier renders the gearbox almost superfluous; we stayed in the green band on the rev counter without having to shift ratios. Only during descents did I-Shift choose to drop a gear or two to check our speed with the Volvo Engine Brake (VEB) in order to remain inside the speed limit.
The FH cantered up the first real test, the long timed hill climb at Holmescales Hill from J36 of the M6 at Kendal, setting a time that is unlikely to be beaten at 44 tonnes GCW.
Handling and steering are inevitably compromised to some extent by the non-steering second axle on this 6x2 configuration. It is not an issue when circumnavigating large roundabouts such as those usually found near motorway junctions, for example. However, on smaller roundabouts, like the five on the A692 around Consett, Co. Durham, the conflict between the axles’ direction is evident and unwelcome in a truck of this standing. But is it enough to convince operators to shoulder the extra cost and weight of the optional steered mid-lift axle? Probably not.
During tight manoeuvring, such as the 90° turn into the lorry park, we employed traction-assist, to avoid leaving too much of the tyres behind on the tarmac. That dumps some of the air from the mid-lift axle’s air suspension, relieving the axle of some weight.
The Globetrotter XL’s lofty cab gives the driver a good view in most circumstances, but the lower edge of the storage units above the windscreen restricts the view when looking skywards.
The large mirror on the driver’s side also tends to create a rather hazardous blindspot when entering roundabouts. Volvo reckons the new FH cab (CM 13 September) tackles these issues, with a larger glazed area and slimmer mirrors.
Productivity
Experience tells us that you pay twice for really powerful trucks – once when you buy them, and again every time you refuel them. Previous CM road tests of trucks with more than 500hp never cracked the 8.0mpg mark, making our expectations for the 750hp Volvo modest, to say the least. So an overall figure of 8.71mpg ranks as an outstanding and surprising result, reminding us that records are there to be broken. It is good enough to put the big Volvo into second place on our 44-tonne tractor unit fuel economy leader board, albeit half a mile per gallon behind the MAN TGX 26.440 (CM 1 December 2011).
It is a significant improvement on the 7.81mpg achieved by the FH16 700 Globetrotter XL (CM 15 October 2009); that had a hub-reduction axle. It is a whole 1.2mpg better than the Scania R730 Topline (CM 31 March 2011), which returned 7.51mpg.
Closer analysis of the fuel figures shows that the surprisingly good fuel economy is founded on the 9.39mpg during the motorway section and the 9.09mpg achieved through the trunking section. Between them, these two sections account for 84% of the whole route and the FH was able to complete them operating almost exclusively at peak torque, with minimal gearshifts and without deviating from the pre-set cruising speed, irrespective of the topography.
AdBlue consumption worked out at 5.8% of fuel consumption, a little more than the 4%-5% we normally measure around this route.
One might have expected all that power and torque to make themselves felt in a stunningly fast average speed, but that is not the case. At 73.2km/h Volvo is quicker than the Scania R730 by 1.5km/h but a tad slower than two less powerful vehicles at 44 tonnes GCW – Renault’s Premium 450.25 (CM 6 September 2012) and MercedesBenz’s Axor 2543 (CM 29 March 2012). We guess our scrupulous adherence to speed limits and our selfimposed 85km/h motorway cruising speed leave very few opportunities for powerful trucks to really show what they can do, and traffic conditions on the day may prove to be the real determinant of journey time.
At least the FH16 had the opportunity to show its mettle by romping up the two timed hill climbs. We have already remarked how it cruised up Holmescales Hill, covering the 5.8km in 4 minutes and 26 seconds, equating to an average speed of 78.5km/h. This is 16 seconds quicker than an Axor with a 430hp engine and 21 seconds quicker than a Premium boasting 450hp, all at 44 tonnes GCW. The FH16 750 really stamped its authority on our second hill climb at Broomhaugh Hill, a 1.9km ascent from the roundabout on the A68 outside Corbridge in Co. Durham. It raced up in just 2 minutes 13 seconds, a minute quicker than the Premium and 1 minute 20 seconds faster than the Axor. Hugely impressive.
So the Volvo scores well in terms of performance and fuel economy, but what about the third leg of productivity – payload? The news is mixed. Compared with other big trucks with big engines we have tested, its kerb weight of 9,010kg looks reasonable. That is with 550 litres of diesel but excluding the driver. Measured on the same basis, the Scania R730 Topline weighed in at 9,300kg, although that was a twin-steer, inherently a heavier configuration. The FH16 750 is 700kg lighter than the FH16 700 we tested in 2009 but that had a robust tag axle and reinforced chassis designed to work at gross weights of up to 80 tonnes. Nevertheless, we have to put a 9-tonne kerb weight into perspective. It is around 500kg-700kg heavier than the average 6x2 tractor unit, so productivity takes a real hit if weight is an issue. ■ THE COMPETITION Scania R730 Once you get into the heady territory of tractors with around 700hp, Scania’s R730 is the most sought-after in the UK, a favourite with drivers and owner-drivers. Never mind the price, feel the residuals. Scania has yet to release details of the Euro-6 version of the 16.4-litre V8, other than to list its nominal power ratings: 520, 580 and 730hp. Mercedes-Benz Actros The most powerful 16-litre V8 Actros – the outgoing model – has a nominal 600hp rating and 2,800Nm of torque, so it falls some way short of the FH16 750. Daimler has declared itself uninterested in 700hp tractor units, so the most powerful Euro-6 engine in the new Actros looks likely to be a 15.6-litre in-line six with around 600hp and 3,000Nm. TESTER’S VERDICT There are probably three reasons for buying a truck with a 16-litre engine and well over 700hp: sheer indulgence, faster journey times and shifting STGO loads. The FH16 750 did not set the fastest time on our route, and in all honesty its power and torque are largely wasted at 44 tonnes GCW. That just leaves sheer indulgence.
The FH16 750 represents a significant investment, with its 750hp engine rating and Globetrotter XL cab, plus a bunch of extras, taking its price tag to more than £140,000. Very little of that enhances its earning potential so we have penalised the truck in CM’s scoring matrix. Its payload score is also poor. However, it is rewarded for the ease with which it performs, its comfort, quality and strong fuel economy. We had not expected to be complimenting the FH16 750 for being the first truck with more than 500hp to break – no, smash – the 8.0mpg threshold. Rarely does this level of driver appeal and performance go hand-in-hand with such respectable fuel economy.
The new FH cab revealed last month will surely reinforce the desirability of the next FH16 750. Volvo is yet to reveal how it is upgrading the 16-litre engine to comply with Euro-6 emission limits. Hopefully, it will be able to preserve the fuel economy we found in the Euro-5/ EEV version and new technology, such as I-See terrain-sensitive predictive cruise control, could provide the opportunity to better it.
CAB COMFORT
Unsurprisingly, the majority of FH16 buyers in the UK choose the biggest cab available, the Globetrotter XL. This option costs £1,110 more than the Globetrotter, a sum that buys you 170mm (6.7in) of additional internal height, plus the extra storage that goes with it. Choosing the ‘one-bed+’ package fitted in this cab will set you back another £2,368. This provides a single reclining bunk with a few extras such as a swivelling passenger seat, a Nordic-standard night heater for sub-zero temperatures, a fridge and a table.
The test vehicle also has a ‘Driving+’ package, which is an extra £2,094. That includes goodies such as climate control, roof hatch and a sun visor. The heated, electrically powered mirrors that are also part of the package really ought to be standard on a vehicle at this level, as should remote locking. Other parts of the Driving+ package are nice touches, such as the centre drawer in the dashboard and leather trim. They ooze class and contribute to an excellent working environment.
However, there is no escaping the relative lack of internal space. Standing room is compromised by the rake of the windscreen and the storage lockers above the windscreen, encroaching on what most drivers regard as their space. The flatter front of Scania’s R730 Topline offers a little more room for manoeuvre. There is 1,930mm (6ft 4in) of headroom when standing on the Volvo’s engine cover. That is a generous amount in most people’s books, although Topline offers 290mm – almost a foot – more. For the record, the interior width of the Globetrotter XL is 40mm wider than Topline. The engine cover stands 170mm (6.6in) above the floor.
It is only fair to point out that the new FH cab revealed last month addresses these space issues. For example, the new Globetrotter XL has a lower engine cover, more headroom, less windscreen rake and more rearward travel for the driver’s seat.