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Wed, 06 June 2007 16:58  |
Aaron Allen
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http://www.autoweek.com/apps/pbcs.dll/article?AID=/20060227/ FREE/302270007/1023/THISWEEKSISSUE
Inside Bruce Crower's Six-Stroke Engine
By PETE LYONS
AutoWeek | Updated: 02/23/06, 9:35 am et
Bruce Crower has lived, breathed and built hot engines his whole life. Now
he's working on a cool one-one that harnesses normally-wasted heat energy by
creating steam inside the combustion chamber, and using it to boost the
engine's power output and also to control its temperature.
"I've been trying to think how to capture radiator losses for over 30
years," explains the veteran camshaft grinder and race engine builder. "One
morning about 18 months ago I woke up, like from a dream, and I knew
immediately that I had the answer."
Hurrying to his comprehensively-equipped home workshop in the rural hills
outside San Diego, he began drawing and machining parts, and installing them
in a highly modified, single-cylinder industrial powerplant, a 12-hp diesel
he converted to use gasoline. He bolted that to a test frame, poured equal
amounts of fuel and water into twin tanks, and pulled the starter-rope.
"My first reaction was, 'Gulp! It runs!'" the 75-year-old inventor
remembers. "And then this 'snow' started falling on me. I thought, 'What
hath God wrought.'"
The "snow" was flakes of white paint blasted from the ceiling by the
powerful pulses of exhaust gas and steam emitted from the open exhaust
stack, which pointed straight up.
Over the following year Crower undertook a methodical development program,
in particular trying out numerous variations in camshaft profiles and timing
as he narrowed the operating parameters of his patented six-stroke cycle.
Recently he's been trying variations of the double-lobe exhaust cams to
delay and even eliminate the opening of the exhaust valve after the first
power stroke, to "recompress" the combustion gasses and thus increase the
force of the steam-stroke.
The engine has yet to operate against a load on a dyno, but his testing to
date encourages Crower to expect that once he gets hard numbers, the engine
will show normal levels of power on substantially less fuel, and without
overheating.
"It'll run for an hour and you can literally put your hand on it. It's warm,
yeah, but it's not scorching hot. Any conventional engine running without a
water jacket or fins, you couldn't do that."
Indeed, the test unit has no external cooling system-no water jacket, no
water pump, no radiator; nothing. It does retain fins because it came with
them, but Crower indicates the engine would be more efficient if he took the
trouble to grind them off. He has discarded the original cooling fan.
So far he has used only gasoline, but Bruce believes a diesel-fueled test
engine he is now constructing-with a hand-made billet head incorporating the
one-third-speed camshaft-will realize the true potential of his concept.
Potential.and Questions
Crower invites us to imagine a car or truck (he speaks of a Bonneville
streamliner, too) free of a radiator and its associated air ducting, fan,
plumbing, coolant weight, etc.
"Especially an 18-wheeler, they've got that massive radiator that weighs
800, 1000 pounds. Not necessary," he asserts. "In those big trucks, they
look at payload as their bread and butter. If you get 1000 lb. or more off
the truck."
Offsetting that, of course, would be the need to carry large quantities of
water, and water is heavier than gasoline or diesel oil. Preliminary
estimates suggest a Crower cycle engine will use roughly as many gallons of
water as fuel.
And Crower feels the water should be distilled, to prevent deposits inside
the system, so a supply infrastructure will have to be created. (He uses
rainwater in his testing.) Keeping the water from freezing will be another
challenge.
But the inventor sees overriding benefits. "Can you imagine how much fuel
goes into radiator losses every day in America? A good spark-ignition engine
is about 24 percent efficient; ie., about 24 cents of your gasoline dollar
ends up in power. The rest goes out in heat loss through the exhaust or
radiator, and in driving the water pump and the fan and other friction
losses.
"A good diesel is about 30 percent efficient, a good turbo diesel about 33
percent. But you still have radiators and heavy components, and fan losses
are extremely high on a big diesel truck."
Bottom-line, Bruce estimates his new operating cycle could improve a typical
engine's fuel consumption by 40 percent. He also anticipates that exhaust
emissions may be greatly reduced. It's all thanks to the steam.
"A lot of people don't know that water expands 1600 times when it goes from
liquid into steam. Sixteen hundred! This is why steam power is so good. But
it's dangerous."
The danger of a boiler explosion has long been a factor in engineering-and
in operating-steam powerplants of all kinds, and Crower is properly wary of
the miniature boiler he has conjured up inside his test engine. That's one
reason he chose to use one originally manufactured as a diesel, for its
inherent strength, though he installed a carburetor and ignition system so
it could burn gasoline at first.
The original diesel fuel injector system now supplies the water spray to
generate the steam-stroke.
In addition to producing extra power, the injected water cools the piston
and exhaust valve, which suggests to Crower that he could raise the
compression ratio. "I've done this many times on regular engines: 15-to-1 on
gasoline for the first five seconds works pretty good until you get some
chamber heat and then suddenly it gets into pinging. But with the chamber
being chilled, I bet 12-, 13-to-1 will be no problem on cheap fuel.
"So what we can maybe do is have fuels that aren't quite as good.It'll save
a nickel a gallon not having to keep three grades going."
As for his hope of lowering emissions, Bruce speculates the steam might
purge "cling-on hydrocarbons" out of the combustion chamber. "This thing may
turn out to be so clean that you won't have to have a catalytic converter.
But he admits that's unknown, saying "there's a lot of experimenting still
to be done." Which prospect makes him smile. He thrives on this kind of
challenge.
Bruce's Background
"You've kinda got to be in the cam business and know the dynamics of
engines," Bruce Crower says about how the idea occurred to him. And he
certainly has that background.
He was building and racing hot rods (and hot bikes), manufacturing speed
equipment and operating his own speed shop in his home town of Phoenix when
he was still a teen.
After moving to San Diego in the 1950s, among other exploits he dropped a
Hemi into a Hudson and drove it to a 157-mph speed record at Bonneville.
Inevitably, the inventive and inexhaustible Crower built up a major
equipment business in superchargers, intake manifolds, clutches and,
especially, camshafts. He's also credited with first suggesting a rear wing
to Don Garlits-in 1963, three years before Jim Hall's winged Chaparral.
Bruce Crower is now in Florida's Drag Racing Hall of Fame.
Crower actually had introduced a wing two years earlier, during practice on
Jim Rathmann's 1961 Indianapolis car-five years before Jim Hall's winged
Chaparral. Bruce had been crewing at the Speedway since 1954 (Jimmy Bryan,
second place), and had been part of Rathmann's 1960 victory effort. He was
likewise on the winning teams in 1966 (Graham Hill) and 1967 (AJ Foyt).
Three decades later, in 1998, Eddie Cheever won with Crower cams.
Bruce even produced his own complete Indy engine, a flat-8 that didn't quite
make the field in 1977 and then was rendered obsolete (due to its width) by
the advent of ground-effect tunnels. But the Crower 8 and its automatic
clutch did win an SAE award for innovation.
Today, Crower Cams and Equipment Company employs about 160 people in five
facilities, and manufactures not only cams but crankshafts and connecting
rods-including titanium rods for (unnamed) Formula One customers.
Bruce Crower can't be called retired now, but he's happy to let the company
he founded "roll along" while he "plays with cars." That's how he looks at
the intensive R&D work he carries out in the privacy of his 13-acre horse
property near the rural community of Jamul.
One of several projects is building up Honda S2000 engines for the Midget
raced by his granddaughter, Ashley Swanson. ("I think she's on par with
Danica Patrick," says the proud grampa.)
But his prime focus is proving his six-stroke engine is as revolutionary as
he believes it is. "I've been trying to find something wrong with the whole
basic idea for almost a year," he says, "but I think we're going to have a
very marketable item."
Then he adds philosophically, "If it turns out to be great, fine. If it
doesn't, it's just another year out of my life that I've had a lot of fun
doing something."
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