Driving the economical ‘Purple Haze’

Engines are slowing down, even if trucks aren’t. “Down-speeding” is in, maybe not with you but definitely with cost-conscious fleets and with Joel Morrow, owner and driver of the Volvo VNL760 you see here.

Dubbed “Purple Haze,” it’s a show truck, not for its looks but because it’s equipped with I-Torque. It’s the builder’s latest answer to achieving high fuel efficiency for highway trucks.

The system is impressive enough that it recently won the annual Technology Achievement Award presented by a group of American and Canadian truck writers. I chaired the award committee and confess that I hadn’t put I-Torque high on my voting list, so of course I wanted to experience its supposed wonders. I connected with Morrow at the ATA Technology & Maintenance Council’s recent trade show, and within a few weeks I was seated in his Volvo as we headed out of Delaware, Ohio, where I live.

Morrow, also based in Ohio, owns the tractor, and doubles as a consultant to Volvo, advising engineers on what seems to work and what doesn’t in the way of specifications. He said he talks daily to people at Volvo’s headquarters in Greensboro, N.C. Earlier in his career, he worked for Ploger Transportation, now owned and operated by his brother, Jerry Morrow. Joel drove and worked on truck specs, aiming for high efficiency as well as driver satisfaction. Along with good power and torque, gearing is the key to achieving those things, he indicated.

The heart of I-Torque in his tractor is a 455-horsepower D13-TC, meaning turbo-compounding – a second turbocharger that adds extra power to the engine’s flywheel, so less fuel is fed to the cylinders to maintain rated horsepower and torque.

Next in the powertrain is an I-Shift 14-speed automated manual transmission, which Morrow is evaluating. Production I-Torques use a 13-speed, and both versions have a second gearbox added to a standard 12-speed I-Shift.  The extra low-end ratios provide good startability and allow use of an overdrive top gear and a “fast” 2.16 axle ratio.

A third component is predictive cruise control, which minds a rig’s road speed and anticipates up- and downgrades by ordering changes in throttle settings, transmission ratios and engine braking. The cruise control’s control module memorizes the lay of the highway it’s on and, via GPS locating, knows exactly the layout of every terrain feature.

The next time the truck travels a mapped route, it knows what to do. For instance, downshifting just before the rig hits an upgrade, adding power for the climb, then cutting the throttle and engaging the engine brake on the other side of the hill. Morrow’s Volvo had not been on this route, though, so this feature did not come into play during our drive.

Our route was one I suggested: U.S. 36/state Route 37 eastward out of Delaware and through Newark, then southeast on SR 146 to Zanesvillle and east a ways on Interstate 70.

Terrain in eastern Ohio begins rolling as one approaches the Appalachian foothills, presenting some stiff grades to test a tractor’s strength. It’s also pretty countryside, and we both admired it.

Like most VN series tractors, Morrow’s Volvo was comfortable and quiet, so we could converse in normal tones of voice.

He is a true believer in the I-Torque concept but explained its operation in a matter-of-fact manner as we proceeded.

“Low engine speed saves fuel because pistons operate slower and pump less air,” he said. “Reducing air flow through the engine means it cools less; everything stays hotter, which makes fuel burn better, and a hot exhaust stream makes the aftertreatment system work better.”

Does that mean fewer regenerations? I asked. “None!” he said, swinging his flattened hand horizontally to punctuate the point. That’s a good thing because “regens” use extra fuel to burn off soot caught in the diesel particulate filter’s honeycomb structure. Sufficiently high combustion heat alone is enough to get rid of the soot.

Morrow used a light foot on both the accelerator and brake pedal, and that contributed to a smooth, quiet and safe ride. I peered over at the tachometer and saw that it stayed down toward 1,000 rpm, revving to 1,300 or 1,400 before the tranny upshifted. Engine sounds and vibration were muted, contributing to a relaxed and unhurried mood in the cab, even though he kept highway speed at or just above posted limits.

“In a 70 mph zone, I run at 72 or 73,” he said later, as we were on westbound Interstate 70. That keeps a rig going with the flow of most other truck traffic, and gets freight to its destination on time. Morrow hauls a lot of high-end furniture made in Norwalk, Ohio, mostly out West and as far as the Pacific Coast.

This day we pulled a Ploger van he borrowed from his brother.

It was loaded with bottled water and our gross combination weight was about 73,000 pounds, he figured. He talked about the effects of downshifting on engine revs, referring to the I-Shift’s 12th, 13th and 14th ratios as “underdrive, direct drive and overdrive.”

This is a phrase from the olden days of twin-stick transmissions whose four-speed back-box ratios carried those labels, along with a “low” or “low-low” designation for the start-out gear. Drivers of yore stayed really busy shifting through setups like that, but an automated gearbox like Volvo’s does all that work.

I took the wheel just before we got onto the SR 37/161 freeway west of Newark. High winds had been predicted, and they picked up as a weather front flowed through the region and a bright sun further riled up the atmosphere.

The turbulent air buffeted the van and our cab, and I made constant steering corrections to keep the rig in our lane. This tractor had Volvo’s Dynamic Steering, with an electric motor assisting the hydraulic system. But guiding the rig without staggering to either side was still a chore.

I watched the tach as I slowed to 50 and 55 mph while the freeway wound through Newark and saw that the needle swung to 1,400 and sometimes 1,500 rpm if I put my foot into it a bit, then fell back toward 1,000 while cruising, as when Morrow was driving. It sure beat the fun but stress-inducing days of winding a diesel out to 2,100 revs.

OK, so what kind of fuel economy does Morrow get with his I-Torqued Volvo?

“I’m averaging 10.1 miles per gallon right now,” he said, and most of those are loaded miles. “On one run, running empty, east out of Denver, I actually got 15 mpg. The least I’ve seen is 6.53, and that was in a snowstorm, stuck in traffic, stop-and-go.”

So, down-speeding makes sense and saves dollars. And I reckon it deserves that award. LL