Today's Trucking
products Trucks

SPEC’ING & DRIVING FOR DOLLARS

Posted: August 1, 2014 by Jim Park

Can anything be done about the rising cost of fuel?

Unless your cousin is related
to the chauffeur of an influential OPEC oil baron, the prospect of influencing the price of crude oil is pretty slim. But you can certainly lessen the pain.

It may be easier said than done after years at the wheel, but the quickest fix is to adopt a more conservative approach to the way you drive. No expensive add-ons, no time-consuming training sessions, no snake oil. Just an attitude adjustment.

How much impact can driving habits have on fuel economy? Depending on how you’re doing now, about $10,000 a year isn’t out of line, with almost no effect on your day-to-day operation. Smarter driving can earn you an increase of almost two
miles per gallon.

The Sound of Money
From a personal perspective, I’ve grown to hate the sound of an engine running
anywhere above 1600 rpm. It just sounds expensive. When progressive shifting
became an issue many years ago, I tried it, and found that the engine ran much
quieter at the lower rpms and shifting was considerably easier as well. I had the
benefit of some good training in the proper operation of a modern, electronic diesel engine, but don’t take my word for it.

Here are some tips from recognized industry experts on how to spec an engine and more importantly, how to drive it.

The folks at Caterpillar refer to Jim Booth as a senior applications engineer.
Actually, Booth is a small fleet owner who ‘test drives’ all of Cat’s prototype
engines under real-world conditions in his own fleet. He’s also a recognized
expert in fuel economy, and he says it’s as much a matter of habit as anything else.

“There’s no secret to it,” he says. “You just have to decide that you want better fuel economy and don’t stray from your goal.”

Booth says he’s heard many drivers say they have trouble getting used to the
different sound the truck makes when it’s going slow, and a harder time still
watching the scenery just crawl by. “But,” he says. “it’s particularly tough to ignore the ribbing you’re going to take for not running with the pack. These are all just habits, things you can change right now with no up-front cost, no modifications and no technology, just good old fashioned discipline.” Booth’s key fuel-saving tip?
“Gear fast, run slow.”

That’s become a common idea, and a good one, but there’s a limit. Cummins engineer Steve Bellinger says there’s
absolutely no point in gearing a truck so it can run at 100 mph.

“You’ll get your best fuel economy if you use operating techniques that result in the
lowest number of engine revolutions per mile,” Bellinger says. “But that doesn’t mean gearing the truck so high that you’ll have to run two gears back to keep it under 65 mph.”

The thing you have to remember about gearing is that transmissions are designed to create the least internal friction in top gear. According to Bellinger, running one or two gears back means you’re sending power through too many gear meshes,
which is terribly inefficient.

Drive Your Spec
Alan Hertzog, supervisor of service training for Mack Trucks, says that better fuel
economy begins with the engine spec. Its power curves indicate the engine’s
performance characteristics, and by interpreting that information you can figure
out how to drive it best.

Hertzog warns against spec’ing the engine for economy and then driving the
daylights out of it. “Be realistic when you begin to spec the truck, and go with an engine that runs the way you’re going to drive it.”

You’ve also got to understand torque and use it to your advantage. “Torque is what gets you moving and keeps you pulling under load,” says Dwayne Barnett of North American Truck Training Center in Brantford, Ont. He’s also a contract driver trainer for Volvo Trucks Canada. He says there’s much to be gained from judging accurately when to shift on a hill.

“It’s a judgement call whether or not to drop a gear right away,” Barnett says. “If you think you can pull the hill without shifting, go for it. But sometimes it’s better to
drop a gear just as you begin to climb, then let torque do the rest.” Be careful to
avoid dropping below the peak torque point though; things will begin to fall apart
pretty rapidly after that. You may find yourself having to grab two gears instead of
one on the next downshift.

The Boost Gauge
One of the most under-utilized fuel-saving devices on a truck today, according to Chuck Blake, staff application engineer at Detroit Diesel, is the turbo boost gauge, sometimes called the intake manifold pressure gauge. Not many trucks
have these gauges any more, and that’s unfortunate.

Burning fuel produces exhaust which spins the turbocharger, forcing air into the intake manifold. Excess intake manifold pressure means you could be burning more fuel than you need. Blake says there’s seldom a reason to push the boost pressure any higher than 15 psi.

“If you’re getting up past that mark, you’re being too aggressive with the throttle,” he says. “Use the boost gauge as an indicator of how much throttle you need to maintain modest acceleration.”

Blake also says that in some situations, cruise control can actually cost you money.

“Cruise control is a fairly aggressive throttling mechanism. It’s designed to
keep the truck at a steady speed, which the computer may decide requires a
full-throttle application,” he says. “A driver can usually out-do cruise control for fuel economy by simply letting up on the pedal a bit when climbing a rolling hill. Ask yourself if you really need to hit the top at the preset speed?”

The bottom line in all this? You can’t suck and blow at the same time. If you want to
go up and down the road like Jack the Bear, today’s engines will deliver. If you’re thinking in terms of maxing out your RRSP at year’s end, today’s engines can help you do that too, but you can’t do both. What becomes of your hard-earned money is pretty much up to you.

Saving Fuel In the Real World
We figured a real-world examination of two dramatically different driving styles would best tell this story, so highwaySTAR enlisted the aid and considerable driving skill of Donny De Graaf.

A company driver with W. A. Baker Trucking of St. Catharines, Ont., he hauls
newsprint from a recycling depot in Markham, Ont., to a paper mill in Thorold, Ont.
He runs two 192-mile round trips per day, beginning around 4:00 a.m. when the
roads are quiet, then again at 11:00 a.m. He’s empty one way.

De Graaf’s 1995 Freightliner Classic has a 70-in. flat-top bunk, with an aerodynamic wing on the roof. Under the hood sits a 470-hp Series 60 Detroit coupled to an Eaton Fuller 8LL transmission running out to a 46,000-lb rear axle with 3.55 gears. The whole thing sits on tall, 24.5-in. rubber. The tri-axle trailer, an East Unloader walking floor, has external ribs and a soft tarp on top.

You’ll agree it’s not the most aerodynamic outfit on the road, but you’d never
guess that from the numbers De Graaf turned in on the second trip of the day. The
idea was to have him break all the rules on the first trip, then make an extra effort on the second run to squeeze the best mileage he could from his big Detroit,
without being ridiculous about it.

Trip #1 – Empty from St. Catharines to Markham at 39,800 lb. De Graaf
deliberately, and against his nature, took every gear right to the pin and did the
trip at 120 km/h, running at 1675 rpm. We idled the truck for an hour while loading,
then headed back with a gross of 105,640 lb., cruising at the same speed using all the bad driving habits De Graaf could remember. The result: he burned up 35.2 gallons of fuel for an average consumption of 5.45 mpg. Using $0.65 per litre as a
benchmark, De Graaf’s cost per mile for fuel alone in go-faster mode was $0.54.

Trip #2 – Same route as the first trip. This time De Graaf practically idled up
through the gears and kept his speed down to between 95 and 100 km/h, revving the engine no higher than 1400 rpm. We hit heavy traffic on the way to and from Markham, but he kept a steady pace and hardly touched the brake pedal. In other words, he used the exact opposite driving style. Going back to the mill we grossed 106,520 lb. The result: 27.6 gallons of fuel up the stacks for an average fuel consumption of 7.06 mpg and a fuel cost of just $0.42 per mile. Big
difference.

As our unscientific test suggests, driving style is a significant factor in achieving better fuel economy. If you’re averaging 5.5 mpg over 100,000 miles a year and you’re getting paid a buck a mile, fuel devours more than half of every dollar you earn – 53 cents, to be exact. On the other hand, a truck averaging 7.0 miles per gallon is consuming only 42 cents of every dollar earned.

Five Tips to Save a Buck
Forget miles per gallon – learn to equate fuel consumption with cost
per mile. Miles per gallon is a fairly intangible number, while cents per mile has a
real value.

Spec your truck, then truck your spec – consult the engine charts
before you build the truck, then drive it the way you designed it to be driven.

Easy does it – use the turbo boost gauge as an acceleration meter. Try to keep the intake manifold pressure to a minimum. Anything over 15 psi means you’re probably in too much of a hurry.

Maintain a steady speed – let traffic flow around you and maintain
adequate space so as to avoid having to brake or accelerate to keep up with traffic. Get used to driving slower than everyone else.

Progressive shifting – this is probably the most overstated and underutilized fuel saving theory known to mankind. You can go through the bottom
of the box without ever exceeding 900 rpm. Shift at the absolute minimum rpm for
each gear.

Share

  • This field is for validation purposes and should be left unchanged.
Related Articles
TodaysTrucking
TruckNews