combines diesel efficiency with lightweight construction, high engine
loading, and good aerodynamics to push fuel economy well past the
100-mpg mark. Hence its name, "Centurion", for breaking the 100-mpg
barrier. The idea for Centurion was initially discarded because it was
too simple. The proposal was to use an existing lightweight automotive chassis, install a
high-efficiency diesel engine, replace the heavy steel body with a
lightweight foam-core sandwich body, and presto: super fuel economy.
But after initially rejecting the idea as too simple, we decided to go ahead with
it - mainly because it was so simple. And the fuel economy techniques can work
with any vehicle.
technology used to produce Centurion's high fuel economy is very
straightforward. An internal combustion engine runs most efficiently
when it is operating at 60% to 90% of maximum output. In contrast, when
an engine is throttled so it develops only a small portion of its power
output capability, fuel economy plummets. Automobiles operate most of
the time with the engine throttled to 5% or less of full power, such as
when cruising at low speeds in urban traffic. Even on the highway, the
average family sedan can cruise at 55 mph on a little as 8 to 10 hp,
which is only a fraction of the power capability of the engine. An
engine throttled into fractional power regions can use double or triple
the fuel per unit of power output. It's as simple as that.
Centurion first reduces road load by keeping weight and aerodynamic drag to a minimum
with its sleek shape and low, 1,200-pound curb weight. Minimum installed power, tall
gearing, and a transmission with high ratio selectivity combine to allow for high engine
loading. With its 17-hp, 3-cylinder Kubota diesel engine coupled to the 5-speed
transmission with overdrive in each gear, the engine can be loaded into its region of
minimum brake specific fuel consumption at just about any speed. These are the primary
factors responsible for Centurion's fuel economy at cruise. Stop-and-start fuel economy
benefits from low weight, which translates into less energy lost to inertia in urban
traffic. Reduced fuel consumption at idle and during braking results from the
At 35 mph, Centurion delivers at 128 mpg. At 45-mph, fuel economy is 103 mpg, and at 55
mph it drops to 85 mpg. The poorest fuel economy recorded was 64 mpg, which occurred in
downtown urban traffic. Turbocharging the engine would increase maximum power and
performance, and improve fuel economy as well. As originally equipped, Centurion has a
maximum speed of 65 mph.
One builder, however, found that our original fuel economy figures were too conservative.
He has turned in 127 mpg in mixed rural and city driving. You'll find a link to his page at the bottom of this page.
Centurion is one of our most
straightforward super-mileage cars because it consists mainly of an
engine swap and a new body. Its Triumph Spitfire chassis is super light
and relatively inexpensive if you purchase it from a wrecking yard. Total cost will
be in the order of $5,000 - $7,000, depending on how the car is detailed. Using the
original Spitfire engine, instead of the Kubota diesel, could save about 50% on costs. If
you would like more information on building Centurion's body, click on One-Off Construction Using FRP/Urethane Foam Composite (Tri-Magnum is the demonstration vehicle).
Centurion was featured on the cover of Mechanix Illustrated
Magazine and It appeared as a background vehicle in the movie Total Recall. Click
on the images in the left margin to see larger versions.
|Length: 156 inch
Width: 62-1/2 inch
Height: 44 inch
Wheelbase: 83 inch
Front Tread: 51 inch
Rear Tread: 50 inch
Brakes: Disc front/Drum rear
Curb Weight: 1200 lbs
Ground Clearance: 6 inch
Turning Circle: 24 feet
Fuel Capacity: 10 US gallon
Seating: Two, side-by-side
Power train: Kubota #D 750 BB Diesel
Power: 17 hp @3000 rpm
Displacement: 46.5 cubic inches
Bore: 2.68 inches
Stroke: 2.76 inches
Compression Ratio: 22:1
Number of Cylinders: 3 in-line
Type: Vertical water-cooled 4-cycle
Weight: 181 lbs
Transmission: 4-speed, manual-shift, full syncro with overdrive
Final Drive Ratio: 3.98:1
Body: Foam/Fiberglass sandwich
128 mpg @ 35 mph
103 mpg @ 45 mph
85 mpg @ 55 mph
65 mpg in city traffic
Top Speed: 65 mph (in overdrive)
Special lubricants: Transmission filled to factory specs with Torco MTF
fluid. Final drive filled to factory specs with Torco Hypoid 90 gear lube.
Meet Crazy Jerry's Urba Diesel Centurion Jerry's Centurion gets better fuel economy than the original. To paraphrase Jerry, it makes you think the fuel gauge is broken. You'll also find photos of an example of Centurion that looks even better than the original. A beautiful rendition. And you will undoubtedly enjoy the screen-grabs of Centurion in the movie,Total Recall.
Driven by builder Jerry Bartlett (Crazy Jerry), his modified and optimized Centurion tied for first place at the fuel economy competition at Watkins Glen International Speedway in New York. Fuel economy - over 200 mpg. Jerry's modifications include a further reduction of weight, improved aerodynamics, careful attention to friction throughout the vehicle, and optimizing gear train ratios. Jerry's vehicle exemplifies what can be done by careful attention to the details.
Video from inside cabin at start of fuel economy competition.
Essential Resources for the Do-It-Yourselfer