They also power Volvo's trucks around the world as well as Renault trucks in Europe and other markets. (In the Volvo products there's currently a bigger engine: the 16-liter D16 – see next month's Heavy Duty Trucking for Volvo VT880 test. Mack will get that big motor next year.)
The two new engines are significantly different from the earlier Mack power. They are physically a little longer, though narrower than their predecessors. They have integrated exhaust aftertreatment systems (diesel particulate filters). And they flow more exhaust gas in the recirculation so they need more, optimized cooling.
As a result, the new engines demand longer hoods and different "packaging" in the chassis. This means that while the Pinnacle may not look a whole lot different from the Vision it replaces, it most certainly is.
In fact, says David McKenna, the powertrain sales and marketing manager who rode along with me on this 500-mile test, only about 25 percent of the Pinnacle carries over from the Vision.
Mack's home city of Allentown, Pa., was the base for a two-day evaluation of the 2008 Pinnacle with the 13-liter, 800-cubic-inch, MP-8 diesel. Day one was spent in the Poconos, hauling up a series of sharp grades – mountains, even – as we negotiated I-78, I-81 and I-80 north of Allentown on a big loop of nearly 300 miles. We were in a truck specially built to honor U.S. servicemen killed or injured in battle, and it was a moving experience to drive this truck and get the thumbs-up from many other drivers, truckers and four-wheelers alike.
To make it work, we were loaded to 76,000 pounds GCW to feel the performance of the new diesel.
Day two saw us heading down I-78 toward Hagerstown, where the route settles out to more level running. I wanted to see what sort of fuel mileage potential the new engine has, cruising along at 58 to 60 mph, letting the truck run out on the down grades and keeping out of the engine brake as much as possible.
The Pinnacle was first announced along with the engine lineup in late 2005, but didn't really make much of an impression until 2006 when a few appeared with early MP-7 new generation engines. These were early production models from Mack's Hagerstown facility. The earliest Pinnacles were mostly demonstration units with the 11-liter, running in '04 configuration without the diesel particulate filter because low sulfur fuel was in short supply. In fact, we drove one briefly from the Poleman Transfer fleet out of Wadeena, Minn., about a year ago.
The Pinnacle is produced at the Volvo New River Valley plant in Virginia, alongside Volvo's VN. When the Mack production shifted there with the closing of the Winnesboro, S.C., plant several years ago, the opportunity was taken to combine the best of the frames between the two brands. But to satisfy the Mack design and performance criteria, only about 60 percent of the frames came out as common. Many compromises that would have diluted the Mack-ness of the end product were resisted, so there are significant differences amid the similarities of the Volvo and Mack products.
Another change that goes back a few years is the improved durability of the Pinnacle cab. This comes from the introduction of the Granite construction range that featured a severe-duty version of the cab, with extra gusseting, different sections and so on. These have now been incorporated into all the cabs on the Mack products, adding around 30 pounds to the Pinnacle, but gaining enhanced durability in exchange.
The interior space is better, especially on the daycab, where the B-pillar is extended and seat mountings have far more fore and aft travel. The hood is longer, so the cab sits a little further back from the all-new cooling package that has a fan ring. And, on the axle-forward Pinnacle, the "eyebrows" over the grille with the associated Mack "belt buckle" disappear, along with the big, bold M-A-C-K letters. Instead there's a rectangle grille and a subtle "MACK" down at the bottom right.
Under the hood of the test unit was the 13-liter (800-cubic-inch) MP-8. New for the 2007 emissions certification, the MP-8 shares the same architecture as the smaller MP-7 and the upcoming giant MP-10 (if you hadn't guessed, the numbers in the Mack designations refer to displacement in hundreds of cubic inches). They are all overhead cam, as was the Volvo D12 on which they are based, but with the camshaft and auxiliary drive moved to the rear of the engine. Injection pressure has jumped from the D12's 25,000 psi to 36,000 psi and, since the pressure is generated by Delphi Gen 3 unit injectors off the camshaft, there are major torsional fluctuations in the camshaft drive. These are now fed directly in to the flywheel instead of the nose of the crankshaft, allowing for better damping and stricter control of the injector timing.
The Delphi injectors are multi-event with pre- and post-injection for better combustion control, lower NOx and a significant reduction in diesel combustion knock.
The engines are different: The MP-7 is smaller and 360 pounds lighter than the MP-8 but peaks with 405 horsepower in its line-up (this MP-8 is a 485). Both engines are available with Maxidyne, Econodyne or MaxiCruise personalities. The three are differentiated by torque and rpm curves that deliver performance differently to suit different fleet or vocational needs. Ours was a 485/1,650 Econodyne designed for typical interstate and part load/part throttle application.
Backing up the engine, an air assisted two-plate clutch and a 13-speed Mack Maxitorque transmission completed the Bulldog part of the powertrain. Drive axles were by Meritor with 3.90 to one ratio.
With the double overdrive of the Mack 13-speed, triple-countershaft transmission, the gearing gave 1,370 rpm at 60 mph indicated. Calculating out the road speed with the Bridgestone 22.5-inch M726 drive tires gives us 1,360 at 60 mph. Mack's McKenna says he likes to gear for around 1,400 rpm at 65 mph, so we were turning a few extra rpms.
The engine and transmission sit lower in the frame than the earlier E7 did, which gets some additional cooling to the oil pan, as well as helping with underhood air management. The narrower engine also helps, and the general clean and compact EGR system make it a competent-looking install in the chassis. Downstream, the exhaust runs into a frame-mounted "teakettle" DPF that sits between the very typical Mack stack of air tanks and the fuel tank on the passenger side. From there, a splitter in the exhaust allows for two matching stacks up the outside corners of the back of cab.
The stacks were relatively short because the Pinnacle featured a mid-roof and no cab fairings of any kind. It did have some fine-looking step/storage boxes and checker-plate fenders, with polished tanks setting off the stirring murals.
IN THE CAB
One of the new features for the Pinnacle is a sweep-around dash behind the smart, engineered-looking steering wheel. The dash is unusual with its mixture of round gauges and driver information panels. McKenna said the shape of the upper panels was intended to maximize dash real estate, without having displays that get hidden behind the wheel. And it works, with the driver info panel front and center, and the engine coolant and fuel gauges right where you can't miss 'em. Idiot lights are in these panels too.
The driver display is a triumph of usability. The screens are clear and well-organized, with the information a driver wants to see. Moreover, the column stalk, with only an up/down rocker, plus enter and escape buttons, is so intuitive, anyone can use it within seconds of being introduced.
Other switches are where you expect to see them on the wing panel, where cruise, engine brake and so on are convenient to use. The light switch is low to the left of the steering column, where you can reach it from the ground (good for trailer hook-up.) The designers and stylists resisted putting the ignition key down there, where it is all too easy to break off with the left knee when climbing out of the truck.
Drivers used to a CH or even a Vision will be surprised by the seat adjustment. You can fling the seat all the way back and find you can't work the pedals – unless you're 6-foot-8. I had to pull it up several notches. Seats at this trim level and on this unit were inviting-looking, with lots of adjustment and heat as well. I should have spent more time adjusting the front bolster, because by the end of the second day I was sensing the seat was short. But that was my fault, because I failed to stop long enough to work out how to extend the seat to better support my legs.
The rich brown leather seats sit nicely far apart in this wide cab, so even with armrests, there's a full 14 inches of walkthrough to the sleeper. But the center console stack, which has big cupholders, a useful shelf and a big storage bin, means that the seats need to be pushed to the rear when standing up from either driver or passenger seat. Also, as a mid-roof cab, there's somewhat restricted headroom that requires a stoop when getting up from the seat.
There's the usual storage in the header and rather stylishly trimmed door pockets. The CB radio mount, though, sits on the top of the dash and is not as nice as some of the solutions we have seen in other new dash setups.
Mind you, considering this was not the top of the line trim, it was still very comfortable. The cab floor had a fitted, thick rubber mat that no doubt contributed to the low noise levels. Somewhat whimsically, the mat has embossed doggy paws all over, carrying through the Bulldog theme.
The rich leather of the seats is repeated in the crunched leather stripe that sets off the comfortable sleeper. There's full standing height back there for anyone up to 6-foot-3. Useful shelves that would accommodate duffels and sleeping bags are fitted high on each side, with provision on the passenger side for a TV and other electronics. Beneath this is a wardrobe with a shelf over, but under-bunk access to the baggage compartments was all the sleeper storage that was provided in the test unit, with precious little other provision for clothes or other personal effects.
As noted previously, this was a fairly conservative spec and was headed for a fleet operation. An individual could significantly enhance the usability of the sleeper by optioning many of the cabinets and comfort items in the data book.
ON THE ROAD
After a comprehensive walkaround, I took the wheel with McKenna beside me, looking forward to stretching out the 485 horses as we headed east out of Allentown. But first, some negotiation of the suburban neighborhood around Mack's headquarters showed the truck turned very well. The visibility forward and down to the road surface through the deep windshield is generous. The sides and mirrors to the rear are greatly enhanced by the side windows, which are devoid of wing windows and sweep down toward the front. This results in a very open feeling to the Mack Pinnacle and inspires confidence in the first few minutes of getting under way.
Heading out of Allentown, whether east or west, there's a strong pull out of the valley, but despite the 76,000-pound GCW, we made relatively short work of the grade. Much of the early going was in and out of the succession of hills and valleys that lead up to the Poconos. Once in the big hole, most of these grades took a single split down to breast, though sometimes lugging down to 1,100 rpm or even 100 rpm less. But the 13-liter remained strong even down below the flat peak torque that has 1,650 pounds feet between 1,100 and 1,300 rpm.
A few grades in the first stretch took a full gear down, but once in to the mountains, there was plenty of gearing down to make the significant grades encountered. The lowest we saw was two down in the lower split – or eighth in the 13-speed Mack transmission. This, by the way, is the absolutely bulletproof triple-countershaft box that has a very positive shift quality. It has a different rhythm than an Eaton Fuller, thus requiring a little extra practice to get the shifts right, and with only a couple thousand miles on the truck, it was a little heavy. Experience shows the shift eases up with more miles.
The 13-liter acquitted itself well, giving smooth torque delivery and responding promptly to the throttle in the way we have come to expect from engines with variable geometry turbocharging. One thing that was apparent was the sensitivity of the foot feed. Any pressure on the pedal – even just a brush of the foot – would bring up the rpms. As a result, a conscious effort to remove any pressure had to be made when easing up through the gears.
The engine was impressively quiet. Multiple injection events to cut NOx from the engine also serve to significantly reduce diesel knock, and with its particulate filter damping out exhaust pulses, there was no exhaust bark to this Bulldog. There was no trace of the timing gear noise at idle I had noted on the prototype Pinnacle I drove a year ago. I had deliberately looked for any noise because the timing gears are at the rear of the engine. On this production Pinnacle, the bulkhead and doors are impressively sealed. The idle noise was just 59 decibels, with the engine making very little contribution to the overall noise at a 60-mph cruise. Here I recorded 75 dB(A) rising only to 76 at the full power test (45mph at 75 percent rated engine speed). And using the very effective engine brake – the PowerLeash – brought little noise, again thanks to the DPF.
As noted with previous Macks, the ride and handling were good, especially considering the state of much of the highway we encountered. One wonders what Pennsylvania does with the money it collects in fuel taxes – a lot more of it could go to highway maintenance. A particularly noteworthy aspect of the suspension is that there are no surprises as the truck leans into the corners; the right amount of steering is easy to apply and no correction is needed. It did take a day to get used to the steering in the straight ahead position – I was sawing at the wheel initially, but by the second day I noticed considerable less activity at the wheel.
Day two was a far different drive, southwest toward Hagerstown where the hills start to flatten out so we could shoot for fuel mileage. Taking fuel information from the driver display, I had found the fuel mileage in the more performance-oriented drive of the day before was 5.2 mpg returning to Allentown after nearly 300 miles. Zeroing the trip and driving for economy – mostly holding 58-60 mph and using the cruise sparingly – I managed to get the fuel mileage up to 5.9 mpg on the interstates. It fell back to 5.8 after negotiating the local streets back into the Mack parking lot.
Of course, this particular truck was spec'd without fairings – not even little cab extenders – and the dry van trailer was also without any Nosecone or similar aids. That can seriously impact fuel consumption, maybe as much as a half mpg. In light of this, the fuel mileage doesn't look bad.
McKenna says the new engines are as good as or better than the ASET E7 engines they replace and was hoping for the low- to mid-sixes or better. He was a bit baffled but thought the cause might lie in the DPF as well as the lack of fairings. The tea-kettle design – known as the Mack Cap – has an annular passage through which the exhaust passes to reach the ceramic filter. It seems that many of the earlier deliveries of the devices have a too-tight clearance. When this happens, the exhaust backpressure rises and the system does not fully regenerate, leading to some loss of performance and to poorer fuel economy. It may be the case here.
The excellent driver display has been noted. It's worth returning to it, because the screens available are very well-designed to give the driver, technician and owner all the information very simply and intuitively. I had assumed, because the control stalk was the same as Volvo's, that the rest of the system would be the same, but it is entirely a different interface and much easier to use than Volvo's.
Another factor that will appeal to the driver – at least on this truck – was the back of cab access via the storage boxes. I was surprised the cab access was not as convenient, lacking a low-mounted grab handle at the hinge side of the door opening.
The engine access is good, even with the added complexity of today's EGR systems. In fact, the new engines are considerable cleaner, externally, than the earlier E7, with components that might need service easily accessible.
A nice feature of the Volvo/Mack EGR is a "short-circuit" in the plumbing that returns exhaust gas back to the turbo to raise the temperature of the exhaust and aid in the active regeneration process. Mack, like Volvo, also uses the VG turbo to raise exhaust backpressure during start-up to get the engine up to working temperature faster.
The phrase "Built Like a Mack Truck" has passed into the language. There's no denying the Mack is a tough truck. The refinements to the cab make it very durable, and in over-the-road applications with new chassis and cab upgrades, there can be no doubt that Mack's enviable reputation for toughness will ensure a long life.
Now that the troubles of the E7 engine are a thing of the past, the reliability that was lacking in the last few years has been addressed. McKenna proudly pointed out that, even as new as the engines are, they are much, much more reliable than the E7 at the end of its development.
Mack products – because they have such a high Mack content – possess an individual character. And despite the commonality of some components with its sister division, the distinctiveness that spells Mack is patently displayed in the Pinnacle. To the driver, it means a particular style, particular driveability, particular performance and particular durability.
And with its legendary durability on track, the Bulldog is back on the Pinnacle with the MP-8.
Test Vehicle Specs
Tractor Mack Pinnacle CHU603
Frame STEEL-266 X 90 X 8MM
Engine Mack MP8 484-C 485 @1800 rpm, 1,650 lb.ft @ 1100-1300 rpm
Clutch CL79815.5" ceramic
Transmission Mack Maxitorque ES T318LR 18-speed
Drive Axles Meritor 40-145
Axle Ratio 3.90 to one
Rear Suspension Mack Maxlite 40 AIR SUSP40K 52" spread
Front Axle Mack FLX12 12,K
Front Suspension Parabolic Taper Leaf 12,000#
Steering Sheppard HD94 STEERING GEAR POWER
Front Meritor Q-Plus 15 x 4 Drums
Rear Meritor Q-Plus 16.5 x 7 drum with
MGM park on rear
Wheels Polished 8.25 x 22.5
Front Bridgestone R287 295/75R24.5
Rear Bridgestone M726 295/75R24.5
Fifth Wheel Fontaine SL3ASB air slide
Fuel Tanks Dual 93 gal aluminum
Cab Mack CAS68 HD Cab
Hood Fiberglass tilt
Cab Aero Options None
Seats Mack Proprietary Ultra-Leather
Sleeper 70" Mid Rise
Paint Black Gold Pearl w/ Cascade Vinyl Applique
Step Heights 17.5/18.5/14.5
Floor height 50.5
Baggage liftover 52.5
Frame ht @ fifth wheel 39
Shoulder width 68.5
Windshield width 68.5
Height at standup point 62
Seat to ceiling 39-47
Belly room 8-20
Walkthrough seats 13
Height at bunk 77.5
Bunk to ceiling 56
Bunk width 38
Clear floorspace 31x42
Left 74' 3"
Right 79" 6"
Closest sight to ground 22' 9"
idle 59 dB (A)
max accel 76
RPM @ 60 mph top gear 1370
Average Fuel Consumption (day 2) 5.9 mpg
Average Speed 51 mph
Gross vehicle weight (on test) 76,000 pounds
Meritor Wabco 318 (18.7 CFM) air compressor; 12V, 135A Delco 35SI alternator: 3-12V Mack batteries; Mack PowerLeash engine brake; 120V 1500 watt block heater; Behr fan and Borg Warner electronic fan drive; aluminum flywheel housing; Davco 382 fuel/water separator and heater/ 12V gear reduction starter; silicone coolant hoses; low voltage disconnect; Mack Cap muffler/diesel particulate filter; Mack Visibility doors w/ passenger peeper window; black polyurethane floor mat; accessory power outlets in center console; Two-spoke 18" leather steering wheel; adjustable steering column w/ telescoping tilt; halogen headlamps/foglamps; polished aluminum air reservoirs; Stemco Voyager rear seals; Haldex auto slacks; aluminum front hubs; power door locks.