[3/4-Ton 7% Grade]
[1-Ton 7% Grade]
[Diesel v Gas Comparison
[3/4-Ton 15% Grade] [1-Ton
15% Grade] [Diesel v Gas
Comparison 15% Grade]
All Grades] [Summary]
Diesel Pickups - 7% Grade With 10,500# Trailer:
same test approach and distance used for the three-quarter-ton gassers
was used to grade the performance of the one-ton diesel pickups.
to space and readability considerations, the bar graphs
below only show the test results from 200-m to 450-m. See the summary
table at the bottom for full test results from 50-m to 450-m.
times and speeds measured are shown cumulative over the run.
the graphs below: the lower a truck's bar is, relative to the other
two trucks' bars, in the "Time Over 450-Meters" graph the
better it performed. The higher a truck's bar is, relative to the other
two trucks' bars, in the "Speed over 450-Meters" graph, the
better it performed.
shortest time required to cover the 450-meter distance determined the
best performing truck.
Diesel Pickups 7% Grade With Trailer Summary
Dodge Ram 3500 Quad Cab 6.7-L I6 4x4 DRW 6-speed auto 4.10
Ford F-350 Super Duty Crew Cab 6.4-L V8 4x4 DRW 5-speed auto 3.73
Chevrolet Silverado 3500 Crew Cab 6.6-L V8 4x4 DRW 6-speed auto 3.73
|50-m / 164-ft
|100-m / 328-ft
|200-m / 656-ft
|300-m / 984-ft
|400-m / 1312-ft
|450-m / 1476-ft
Diesel Pickups 7% Grade Assessment:
final numbers speak clearly when it comes to which diesel powertrain
performed best during the 7% hill climb, but watching it play out in
the time and speed numbers is like witnessing
a chess match. The best individual powertrain components and gear ratios
can't win unless they all work together seamlessly and strategically.
Ram 3500 took the early lead in the first 50-meters, with its torquey
I6 (earliest torque peak out of the three trucks) and 4.10 final drive
ratio. But by the time all the trucks gained some momentum shifting
into second and third gears, the Silverado 3500's slightly higher power
and torque figures - from the Duramax / Allison combo - were transferred
to the pavement more efficiently through its 3.73 rear axle. When both
trucks shifted into fourth gear, near the top of the hill, the Ram's
speed curve flattened out while the Silverado's continued its upward
surprising, though, was the Power Stroke's performance in the Ford
F-350. Out of the box this truck weighed about 1,000-pounds more than
the Dodge or Chevy rigs. Still, we were expecting better off-the-line
performance assistance from PSD's dual sequential turbos, which work
at both low and high speeds to provide up to a combined 42-psi of boost
(versus 20-psi in the uni-turbo Duramax).
variable geometry turbo (VGT) setup in the Ram's Cummins diesel is
also meant to provide low and high speed power throughout the RPM range,
but instead of using compound spinners like the Power Stroke, it relies
on a single turbo paired with a compressor sleeve that slides forward
and backwards axially along the turbo shaft to variably change air
volume and psi-boost to the engine. The same sleeve is also used to
engage the Ram's exhaust brake. It's an elegant solution that tackles
two different tasks.
Silverado's Duramax variable vane turbo system is downright simple
compared to the Ford and Dodge. Its one-piece exhaust turbine relies
on a solid shaft to handle the stress of spinning at 120,000-rpm to
suck in huge volumes of air as needed.
think Ford may not be getting quite the bang for the buck out of its
dual-turbos that Dodge and GM are getting from their air-compression
area needing a good tweak is the F-350's 5-speed transmission.
Its gears don't grow fast enough to leverage the full power and
capability of the Power Stroke. Occasionally the stars aligned
for the Ford to fully loose the power housed in the
PSD. Fourth gear is 1.00:1 on all the trucks,
and this was where the Ford made the biggest jump in speed relative
to the Dodge and Chevy - gaining more than 1.5-mph in the last 50-m.
end result was the Silverado completed its run almost 5-mph
(greater than 10%) faster than the F-350 and almost 2.5-mph quicker
than the Ram. Wow!
Duramax lives for climbing hills under load. We'd feel very comfortable
calling on its power if we needed to pass slower moving traffic up
a long, steep grade.
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