Inside Bruce Crower’s Six-Stroke Engine (design captures waste heat)

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.”

Many manufactures are already addressing the parasitic cooling fan/pulley/belt assembly by running electric fans, something Europeans were doing 40 years ago on their small 4 cylinders. The gain in HP is figured at about 8-10% with an accompanying increase in MPGs. Also if I remember correctly some WWII aircraft engines used a water injection system to cool the cylinders creating a denser gas/air mixture that produced more power for short burst. I also wonder if you couldn't get some of the same increase in efficiency by increasing the compression ratio, adjusting the computer to retard the timing a little and running higher octane fuel thus eliminating the need to haul around a tank of water. I believe water weighs around 8 pounds/gal. If that is right and you need to have equal amounts of gas and water then on my Tahoe I would be carrying an extra 400 pounds at fill up (8lbs/gal x 25gal). That can't help my fuel mileage much.

Mr. Crower needs to talk to the nice folks at Sturman Industries, who have developed electronic valve actuators that do not rely on cams to open and close the valves.

For this application, electronic valves could very much simplify the design of this steam/diesel cycle.

Not very comprehensive if he didn't vent the exhaust to the outside. Test sessions tend to be short after you have passed out (dying) on the floor.

Maybe so, but he's lookin' good at 75.....

......while living the philosophy of KISS.

Rest In Peace, old friend, your work is finished.......

If you want on or off the DIESEL ”KnOcK” LIST just FReepmail me........

This is a fairly HIGH VOLUME ping list on some days...... THANKS AND A BIG HAT TIP TO UNCLE DAVE!...............

Let us know when the perpetual motion engine is completed.

He's not going for or claiming perpetual motion. It does appear that he has a revolutionary new type of internal combustion engine with a much better level of efficiency.

More power to the guy. I'd love to see a 500 hp V8 get 30-40 mpg.

Trucking companies, farmers, anyone who uses diesel fuel in large quantities in a business would buy this technology tomorrow for a 40% increase in fuel efficiency. Guarantee it.

Here’s an example: on each one of by 125-acre pivots, I reckon (more or less) that I’m going to burn 1,000 gallons of #2 per year. Right now, that’s costing me about $2.50/gal, or $2500/pivot.

Assuming that I could buy an engine (or retrofit his ideas) into a tractor engine right now, that would mean that I burn only 600 gallons of #2 per pivot per year. 600 * $2.50 is $1,500, or a savings of $1,000 per pivot per year.

Times four pivots is $4,000 saved per year.

The depreciation lifetime (as dictated by the IRS) for a tractor (or baler, balewagon or other major piece of equipment) or a major improvement that increases the lifespan of same is 7 years. That would be $28,000 saved across all the diesel engines I use.

With that kind of savings, I’d retrofit the tractors immediately if I could. The smaller engines on this place would be second, but the big consumers of diesel are tractors for tillage. $28,000 is more than I’ve paid for any of the three tractors I own now.

It pencils out very well.

So the still burning exhaust gases from the fueled part of the cycle heat the water ... it wiould be the exhaust stroke, but with the exhaust valve closed ... the expanding steam gives another power stroke ... and then when is the exhaust stroke?

A normal 4 cycle engine has:
intake - compression - power - exhaust.

After exhaust this adds:
Water injection/steam power stroke - steam exhaust.

If you can still run the other four strokes just as efficiently, then you are taking some of the waste heat normally removed through the radiator and creating an extra power stroke. If it works well it would be a good way to reduce fuel usage. It isn't a perpetual motion machine as was mentioned above. You aren't getting energy from the water, you are just making good use of waste heat.

Water injection directly to the cylinder would recover the heat energy as you describe. I guess a lot was left out of the article. The "steam" cycle would also leave the cylinder clean of everything including lubrication.

I doubt that the "steam" stroke will produce as much energy as a normal combustion cycle. If the total output is then reduced that would have to be considered in how much performance is improved. I guess we'll see if anyone wants to pursue this further.

You’re using the heat stored in the engine block, piston, etc to flash the water into steam and capture the useful work possible from the residual heat into mechanical energy.

A non-turbo’ed diesel engine puts about one third of the total thermal energy in the fuel into the crankshaft, about one third into waste heat and one third into the exhaust.

Putting a turbo on a diesel engine recaptures some of the heat and pressure energy in the exhaust and puts that back into the engine, which increases the thermal efficiency to a maximum of about 38%, depending on the engine. A two-stroke diesel with a turbo can recapture more.

The highest thermal efficiency diesel engines are those monster two-cycle engines used in container ships — they’re about 48 to 54% thermal efficiency.

So what he’s doing here is capturing some of the waste heat in the engine that is normally put into heating air going across the radiator, and he’s using that to flash some small quantity of water into steam, which expands, and then converts that wasted heat into mechanical energy.

Couple this with a good turbo to capture some of the wasted pressure/heat out of the exhaust, along with some computer-controlled valve timing, and one could have a very highly efficient engine.

My hat’s off to this gentleman — he’s doing some very original thinking.

The original steam engine had two hand-operated valves. The first let steam into the chamber for the power cycle. The second let water into the chamber for cooling. A child was employed to turn the valves. On and off. On and off. The child tied the valve handles to the beam and the motion of the beam then turned the valves on and off. On and off. The child then took off to play.

With modern metallurgy in the rings and liner, as well as modern lubes, this can be addressed.

How much energy the steam stroke will produce will depend on how fast the water’s phase conversion can extract the residual heat. My initial reaction is that this would work really well on an aluminum block engine, because aluminum conducts heat very quickly. Cast iron blocks might not be able to extract as much heat into the water as quickly.

WWII aircraft engines injected water (and in some cases, water+methanol, or water+ethanol) to raise the effective octane in the fuel, to prevent pre-detonation when you pushed the engine into super-high boosted intake pressures to maximize performance in the “War Emergency Power” ratings that were good for only about 10 minutes.

There’s some sharp boys at MIT looking into re-creating this idea in conventional gas engines for cars. If you could increase the octane of gasoline by either injecting water, ethanol or methanol, you could increase the compression ratio and thereby increase the efficiency by gaining a longer expansion stroke on the engine to extract more heat/pressure from the combustion.

Right now, gas engines are at about 9.5:1 compression ratio. If we could get that up to about 12.5:1, we’d see about a 25% increase in fuel efficiency. We need higher octane fuel to make this happen.

Oh — and for all the people who are pissed off about “the ethanol scam”?

Putting ethanol into gasoline raises the octane quite nicely.

> Also if I remember correctly some WWII aircraft
> engines used a water injection system ...

Not just mil a/c.
Water injection was used on large airliner radials
after the war, and elsewhere, if wiki is correct.

More at:
http://en.wikipedia.org/wiki/Water_injection_%28engines%29
normal wikiwarnings apply

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