Super Chief Tri-Flex Fuel V10 Engine
© 2006 PickupTruck.com
enjoyed the “Mad Max” movies but wondered in amazement how
a belt-driven supercharger could be turned off while the engine kept running
will appreciate the V10 engine found in the Ford F-250 Super Chief concept
to burn three different fuels — hydrogen, gasoline and E85 ethanol—the
Tri-Flex engine features a twin-screw supercharger that turns when running
hydrogen. On gas, the boost isn’t needed, so a clutch pack mounted
on the blower’s snout disengages the belt drive. It’s a rather
seamless operation switching from hydrogen to gas or E85 on the fly, but
engaging the supercharger for hydrogen must be done at low speed.
engine is based on the 6.8-liter hydrogen V10 engine that will be utilized
in about 50 E-450 shuttle vans to be distributed to fleets in Florida
and Canada. The engine and van were shown at least year’s Detroit
Auto Show and used to shuttle the press to various events. Now the van
will go into limited production for public use as a way to demonstrate
hydrogen potential. Of course, the hydrogen V10 is based on the Triton
V10 that’s been in the Super Duty for years. And with Ford’s
experience in building about 1.6 million flex-fuel vehicles that can run
on gas or E85, powertrain engineers challenged themselves to combine all
three technologies on one engine.
A dual fuel
system is the most obvious clue to the engine’s unique ability.
Two different fuel rails and two sets of fuel injectors are clearly visible.
The gas/E85 injectors are closest to the intake valve the while hydrogen
injectors are just a little inboard. Supplying hydrogen are 10,000psi
Type 4 tanks constructed of a polymer liner surrounded by a carbon-fiber
overwrap. There is enough capacity for a 500-mile range while running
hydrogen we run very lean,” explains Bob Natkin, a chief engineer
on the project. “Stoicmetric for a gas engine is 14.7:1 and for
a hydrogen engine it’s 34.2:1. With gas you can lean it out to 24,
maybe 26:1 before you get misfire. We can run hydrogen out to 280:1. So
there’s a very broad combustion range we can take advantage of.”
only extreme minute amounts carbon emissions in a hydrogen engine due
only to whatever oil finds a way into the combustion chamber. But NOx
is still an issue. As the engine leans out, NOx is reduced but so is power.
That’s why the supercharger is needed. By adding about 18 pounds
of boost, horsepower and torque close in on the gas levels. A Triton V10
is rated at 310 horsepower with 425 lb-ft of torque. On hydrogen, the
Tri-Flex engine is rated at 250 horsepower with 400 lb-ft of torque.
could go higher on power but then we need a bigger NOx trap,” says
type of technology helps make a current business case for developing a
hydrogen infrastructure and pave the way for fuel-cell vehicles and a
complete renewable hydrogen fuel economy. The upside is that very little
has to be done to an existing gas engine to run hydrogen.
a conventional technology for a very unconventional fuel,” says
Tri-Flex engine looks normal. It runs a 9.4:1 compression ratio and cam
changes are not necessary between fuels. The spark plugs are a cool-temperature
racing type and the ignition is set up to prevent unnecessary spark events,
especially during the exhaust cycle. Ignition timing is also much later
than a gas engine, firing after TDC instead of before.
control in hydrogen mode can be done with fuel, like in a diesel, or with
air through a throttle valve.
can do it both ways and we can pick and choose,” says Natkin.
can run open throttle and increase power with boost and air-fuel ratio.”
limiting factor to fine-tuning the engine is computer memory. Millions
of calculations are needed to read the conditions and adjust the fuel
and spark between the three different fuels. Even though computer modeling
is helping engineers save time, considerable on-road testing is needed
to adjust the numbers. Even the actual engine cost isn’t prohibitive.
powertrain cost under the hood, including transmission, is about $25 to
$35 per kilowatt (1 horsepower is .746 kilowatt). With hydrogen it jumps
about $5 more to $30 to $40,” says Natkin. “Where the cost
comes in is the fuel storage.”
will monitor the E450 test fleets to update their computer models and
test for reliability. Meanwhile, Ford continues to promote flex-fuel options
in many of its vehicles, including the F-150 and is working to improve
the availability of E85. In the future, a diesel-hydrogen engine could
have been discussions about that,” confirms Natkin. “I can’t
tell you if it’s possible. I can’t tell you if it’s
impossible. There would have to be considerable development work put into
such a project.”