There’s no driver in the world who wouldn’t like to have 600 horses on hand, but probably only a handful of fleet managers who’d buy into the idea. Couldn’t live with lousy fuel economy, they’d say for a start. Well, there may be other costs associated with a big motor, but our test of Caterpillar’s brand-new C-16 shows that fuel isn’t necessarily one of them.

Given the chance to combine a 600-horse C-16 with Kenworth’s updated T2000 tractor (see sidebar, page 70), we wanted a tough run. So, with the help of Cat’s fuel economy guru, senior applications engineer and master truck driver Jim Booth, we put together a four-day haul of 2000-plus miles delivering a load of yellow engines to the West Coast.

The trip began at Cat’s plant in Mossville, Ill.

As well as his “day” job at Caterpillar, incidentally, Booth runs a fleet of mostly Kenworth trucks in revenue service, leased to G&D Transportation out of Peoria, Ill. These trucks provide a lot of the performance and fuel economy data for Cat’s development work.

Booth had just acquired our new T2000, equipped with a prototype of the new C-16 engine, introduced to the press last month at the Great American Truck Show in Dallas along with a second model, the C-15.

The plan was to run about 600 miles on each of the first three days, using a combination of Interstates and lesser roads and overnighting in Mitchell, S.D., Billings, Mont., and then Spokane, Wash. We’d finish the trip with an easy 275-mile run down to the KW plant near Seattle. With our load of 14 C-12 and 3406E engines plus two drivers and 179 gallons (U.S.) of fuel, we grossed 79,450 pounds.

THE ENGINE

The new “C” designation in the C-15 and C-16 names bring these big Cats in line with other recent models-the C-10 and C-12-and identify their displacement in litres. The C-15 shares the swept volume of the familiar 14.6 litre 3406E, while the C-16 is the bored and stroked 15.8 litre that was introduced two years ago as the 600-horsepower 3406E.

The old and new engines share more than displacement, but there’s a whole lot that’s different as well. A new block is the most visible difference between the latest range and the 3406E, which it will replace. The new motors are also nearly 200 pounds lighter, thanks to a more efficient block design plus lighter crankshaft, flywheel, bearing caps, and air compressor.

And despite the elimination of the sound cladding from around the block, they’re also quieter.

That speaks well for the new block which, with its convoluted wall design, is now stiffer than before.

Lower noise levels also come from the redesign of the front geartrain, with its high-contact gears that eliminate chatter. An isolated oil pan and sound-attenuating cam cover also limit noise.

Efforts were made to improve the clamping of the head gasket, particularly around the back of the engine where the 3406E can leak oil. Other iron changes also address reliability, with enhanced seal technology in the cam access cover, flywheel housing, oil pan, and elsewhere.

Fuel savings come with the adoption of the latest ADEM 2000 electronics and an increase in compression ratio. The Advanced Diesel Engine Management package is now adopted by all electronic Cats. The latest software adds new driveability and report functions for both off-truck management and on-board driver information systems.

The new electronics also allow rate-shaping of the injection process, which reduces NOx emissions without loss of fuel economy. In fact, Caterpillar says the adoption of ADEM 2000 means the new engines offer slight economy gains over the 3406E, despite 1999’s stricter emissions requirements.

The new engines are also claimed to be easier and cheaper to maintain. Overhead adjustments are eliminated and following recommended maintenance for oil changes and filters, Cat says the C-15 and C-16 save up to 8% versus competitive engines.

Ratings for the C-16 include the 600 with 2050 pound-feet of torque, and a new 575 with 1850 pound-feet. The C-15 comes in a variety of ratings from 355 to 550 hp and peak torque up to 1850 pound-feet. Cat’s not saying anything about future increases to power or torque, but they’re really only limited by today’s transmissions. Our tip would be 2250 pound-feet, with maybe 675 horses for applications like Australian roadtrains.

ON THE ROAD

The T2000 was a dream set-up: the new 600-hp Caterpillar with 2050 pound feetpeak torque, backed up by the mandatory Eaton Fuller 18-speed RTLO20918B with its double-overdrive top ratio of 0.73 to one. The drive axles were Dana Spicer’s (ex-Eaton) DSH40 with tall 3.36 gearing so, despite the 22.5-inch Michelin rubber, the truck was geared to run around 1260 rpm at 60 mph. We elected to cruise at 65.

Booth had supplemented the excellent Kenworth dash display with a Cat ID unit, giving us trip fuel readings as well as individual driver readouts. Before starting out he zeroed the registers that showed the lifetime average economy to that point was 6.73 mpg. The mileage on the truck was just 3343 as I pulled out for the first four-hour stint at the wheel.

We both commented on improvements in noise levels. Jim compared this T2 with another 600-horse truck in his fleet, and I was recalling an earlier test where we were very conscious of engine noise from the bulkhead area.

That’s gone, though subjectively (I’d forgotten to pack the decibel-meter) the T2000 still didn’t seem quite as quiet as the benchmark Volvo VN.

With no serious grades on day one, it was a case of accelerating up to speed after each stop using minimum rpm, certainly no more than 1500 even in the high side of the transmission.

We both shifted whole gears in the lower range, then split the rest, enjoying the light gearshift and the pretty much ideal relationship of the lever to the wheel and seat position.

The C-16 felt very civilized. This is the third 600 Cat I’ve driven and they’ve become very docile in comparison with the prototype I drove in 1997. This year’s introduction of the ADEM 2000 electronics brings additional throttle response and refinement so that while the power curves are not substantially different, the engine has a very strong, progressive hang-in-there quality that makes it easy to drive.

And the economy is pretty outstanding, too. At the end of the first day’s 560 miles we shut down in Mitchell with 6.56 mpg showing.

Day Two: Starting out next morning, I made just one split shift to crest the top of a grade til we changed drivers after 290 miles. Soon we were on two-lane Hwy. 34 to little Belle Fourche, getting a taste of what it was like to truck before the Interstates. Then it was on to Hwy. 212.

There was a lot of road construction to slow us down, but eventually we rejoined I-90 at the Little Bighorn Battlefield. We cruised into Billings with only a single gearshift through what is known locally as a coulee.

There we came down one side with a split to 8th low and the Jake brake rumbling like a Lancaster bomber. Up the other side we crested the grade at 1100 rpm and 48 mph. Shutting down in Billings, our fuel average was 6.44 mpg.

Day Three: Fuelling up just outside town, we added 170.5 gallons. The Cat ID showed average speed for the running miles to this point has been 54.9 mph.

I’m driving again, and we’re looking at big grades as we head into mountains still snow-capped despite the blistering heat of the summer. The grade up to Bozeman takes a split, then a second just near the top.

For Pipestone Pass I came into the climb in 8th low, pulled most of the first section, then grabbed a whole gear for the next bit.

Coming up to the big curve, we’ve rolled off speed and I grab another whole gear, but we’ve got more than enough to spare, so as we pick up speed again, I split back up to 6th high to crest the climb at 6393 feet close to 40 mph.

At mile-marker 25, still in Montana, we’re going up Lookout Pass and signs say, “Truckers: Dangerous Curves. Advise 45 mph.” We top the pass at 32 mph in 6th low, holding the gear down the other side and letting the Jake do all the work.

Unbelievably, somewhere about halfway down at the steepest point, is another sign-“Truckers: No Jake Brake.” Go figure.

The rest of it is straightforward, and then we’re in Spokane, discussing a fun day that finished with a trip-average fuel mileage of 6.48 mpg. But amazingly, the day’s average, even with all the climbing, stood at 6.59 mpg.

Day Four: After an easy drive down off the mountain, the revealing part was the climb back up from the Columbia River heading toward Ellensburg. Starting out with good engine speed as we came off the bridge, and picking up 7th low at around 1700 rpm, the big Cat proved itself again.

Letting it pull to 2000 rpm and then grabbing splits, we found it would have gone all the way up the grade in 8th low. But we were balked by a slow car, demanding a split down. The climb was completed in 7th high.

It says something when a fully loaded truck is balked by car traffic on a grade like this one. And it shows the grade-climbing ability of the C-16 Cat if you can run it where it’s churning out the horsepower.

And at nothing like the fuel cost you might expect.

When we finally set the brakes at Kenworth’s R&D facility in Renton, Wash., 2030 miles from the start, the average economy showed 6.54 mpg for the trip and 6.47 mpg for the mountain section since leaving Billings.

LAST WORD

Caterpillar makes no claim about any performance increase in the C-16 over the 3406E 600, and it would be hard to imagine how you could use much more. But what the new motor does have is the latest electronics for excellent driveability and, despite the EPA emissions rulings of late last year, it has truly remarkable economy.

After all, 6.5 mpg at 65 mph heading west is quite an achievement. Going east, we might have scored an extra mpg!

And the Kenworth T2000? The latest version is an excellent truck with good driver comfort and much improved detail, like the soundproofing, the driving position, and the seating.

I would have been happy to turn the truck around and head back east again with Mr. Booth. And it’s not just his company I’d enjoy.

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SIDEBAR: At a Glance: Cat C-15 & C-16

o At 14.6 litres, the C-15 (below) offers ratings from 355 to 550 horsepower, with peak torque up to 1850 pound feet. The ratings are designed for strong startability on steep grades with heavy loads, and reduced driveline wear since the driver can keep the transmission in top gear longer. Cat pegs the C-15’s B-50 life-to-overhaul at one million miles.

o The 15.8-litre C-16, rated to 575 and 600 horsepower, is being marketed as Cat’s top-of-the-line, high-horsepower powerplant-a “reward” engine. It’s the largest-displacement in-line six-cylinder diesel engine available in North America, producing up to 2050 pound feet of torque at the 600-hp rating (the 575 develops 1850 pound feet of torque).

The C-16 gives drivers more than 720-horsepower of braking capability at 2100 rpm through a combination of the Jacobs engine brake and the Caterpillar BrakeSaver hydraulic retarder- auxiliary systems designed to let drivers control or reduce speeds on long grades or curves, minimizing the use of the service brakes.

Both engine models will be available starting next month.

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SIDEBAR: Kenworth’s upgraded T2000 hits all the marks Kenworth’s T2000 has been a work in progress since its launch in May of 1996. With the re-introduction earlier this year, KW has all the pieces in place and the T2000 is taking its rightful role as the company’s flagship. Indeed, the T2 is now Kenworth’s biggest-production model.

The exterior is unchanged, but development work included a vigorous weight-reduction program, and-even with its premium drivetrain-our T2 scaled 17,600 pounds at the plant. The savings came out of the composite floor and a redesign of many of the brackets and the hardware in the frame and suspension.

Other improvements are driver-related: the 75-inch cab interior has had a complete makeover to re-introduce the diamond-pleat upholstery that driver feedback has dictated. That traditional trim is now found throughout the sleeper, rather than in panel highlights.

The cabinetry has been redesigned to make it easier to spec and easier to use, adding as much as 50% more storage without impacting the available living space in the cab. There’s an excellent slide-out table/desk with useful paperwork storage slots, and a neat magazine rack on the back wall. Crank-open windows help ensure a leak-proof seal and also keep the windows from rattling while providing enhanced flow-through ventilation as you’re going down the road. Soundproofing got the full treatment, too, and the heater/air conditioner has been upgraded.

The driving position seems to have been improved with a simple relocation of the pedal assembly so it’s now straight ahead of the driver, eliminating the offset that proves tiring over time. Also improved is the seating itself.

Our test truck had the excellent European Isringhausen (Isri) model-6800 seats which can be very precisely adjusted. Seat tilt, backrest angle and height adjustments are common enough, but the Isri adds damping adjustment and a quick seat-drop by finger- controlled switches.

There’s also a cushion-length adjustment, and the seat backs have separate lower and upper lumbar support, with variable side bolsters to support the back correctly. All in all, a comfortable ride.