Ultrasonic humidifiers—hang on; I promise relevance—were all the rage in the ’80s. These were great; they made cool fog which humidified the entire space, a giant advance over the boiler types which spewed hot steam and drops of hot water; soaked down the everything in their close vicinity, and made slurp-glurk-whistle-gurgle-flup-flup-flup noises all night, worthy of Don Martin. When I was nine or 10 I had an ultrasonic humidifier in my bedroom up there in the dry suburbs of Denver—a Samsung HU-701A, the one shown; described, and priced (yee! $252 today) in the upper right corner of this April 1985 Popular Science showcase:
Geeky gradeschooler me, I took to playing with it. Next to the water tank was the vapourising chamber and distribution tower. I couldn’t find any pics of a 701A, so this very similar model from a year or two later will stand in:
There was a float switch to cut off the ultrasonic nebuliser if the water ran out, but no interlock to stop the music if the chamber weren’t installed. I discovered a finger could be kept right atop the ultrasonically-energised water stream only very briefly before it started hurting, though I couldn’t figure out what was happening to cause the pain. I got a clue when I immersed my eyeglasses just below the surface of the water pool, with the lens right above the nebuliser: when I removed them after a few seconds, there was a melt-distorted area about a centimetre in diameter. Oops! The lens was ruined; I don’t recall what fib I came up with for my mother about it.
About 15 years earlier, many states away in Florida, a couple of electrical engineers had got to playin’ around with ultrasonics as well, but they were less interested in high-tech finger-cookery or spectacles-melting, and more interested in lowering auto exhaust emissions. This is from the March 1973 issue of Popular Science:
They bought a Slant-6 ’72 Duster and retrofitted it with an ultrasonic fuel system of their own design and build. That’s way cool, even if PopSci’s artist misdrew the car as a ’72 Demon. The chart shows the vastly sweeter breath of the ultrasonic-equipped car, which—compared to the same vehicle with its production Holley 1920 carpotato—put out less than 18 per cent of the carbon monoxide; less than 8 per cent of the unburnt hydrocarbons, and between 8 and 43 per cent of the NOx; that’s massively cleaner.
The chart provides context of ’75 and ’76 US Federal emissions standards as well as other low-emission try-outs: Chev 327 V8s fuelled by propane and by natural gas; a turbine engine, an experimental Mazda Wankel, and a simulated sky-pie Stirling engine. More, the car gave much better gasoline economy with the ultrasonic system, at a time when cleaner exhaust usually meant more fuel consumption. The results are particularly impressive for having been achieved without the feedback (closed-loop) mixture control made possible by the exhaust gas oxygen sensor Bosch was to release a few years later. They’d’ve gone together like water and melon.
Not a word in the whole article about how the car was to drive. But given just exactly what this system did, it would pretty much unavoidably improve performance and driveability compared to a carburetor’s sloppy, halfassed work (hey, just like Jan Norbye’s usual and customary reporting!).
Here we see the car was in fact a Duster and not a Demon. The car had A/C, which makes sense in Florida, and just look how completely the controllers hogged up all the space below the Duster’s under-dash A/C outlet and that funkatronically plaid seat vinyl. Even manufactured computers were great big things at that time, let alone hand-built prototypes like these.
How did the system work? An electronic computer balances engine load (as sensed by intake-manifold vacuum); engine speed (sensed by distributor shaft RPM), and ambient temperature. The computer translates this information into variable fuel pulses, which are then directed to the active surface of a sonic reactor unit […which…] faces two fuel injectors. So they were shooting gasoline at an ultrasonic nebuliser to create a fuel fog much finer and more uniform than the assorted-size, chunk-style droplets from a carburetor.
Leave out the ultrasonic nebuliser, and that’s an identical description of a speed-density throttle body fuel injection system as factory-fitted to zillions of American cars in the 1980s and into the ’90s. But the ultrasonic bit really did the heavy lifting on this one; the output from a throttle body injector is visibly more like a lawn sprinkler’s spray than a humidifier’s fog; better than a carburetor, but nowhere near this much better, as admitted with inadvertent prescience in that first paragraph touting ultrasonic fuel induction as a better method than cleaning up dirty exhaust.
I confirmed my hunch on that by checking the combined, new-scale fuel economy differences of carbureted versus TBI versions of a few different models—’85 versus ’87 Aries 2.2/auto (carb ’85 4.5 per cent better) and ’88 versus ’89 Caprice 305/auto (TBI ’89 5.8 per cent better). Yep, fuel economy improvement with TBI was trivial at best; not close to the ultrasonic’s improvement.
A fuel fog like this what the ultrasonic setup provided does not tend to condense and puddle in the manifold anywhere near so much as a coarser mist. That would put it much closer to one of the big reasons why a dry-manifold system (port fuel injection) works so much better than a wet-manifold system (TBI or carburetor): the intended amount of fuel reaches every cylinder, always.
I really think it was probably feasible—at least very ripe for further development. The results shout loudly, and computers and components were rapidly shrinking and improving at the time, too. The ultrasonic nebuliser and its driver in that 1985 humidifier were altogether a hold-in-the-hand collection of parts.
But instead, automakers stuck with carburetors long past their use-by date, and cleaned up the exhaust with catalytic converters. I doubt it’s because of a flaw in the ultrasonic concept; I have an easier time thinking they saw a flaw in where the idea hadn’t come from. Mind, I don’t claim ultrasonic induction would’ve made catalytic converters unnecessary—maybe or not, but cleaner exhaust in = cleaner exhaust out and much longer cat life.
Also mentioned in the article is that retrofitment to existing vehicles would be easy, and that’s probably right. Looks like they used an electric fuel pump; those were readily available at the time, and the rest of it would just be replacing the carburetor by an appropriately-configured throttle body-injectors-ultrasonics assembly, putting the control box somewhere, and wiring it all up. Easier; safer, and surely more effective than trying to retrofit a catalytic converter—though here again, the ultrasonics would’ve greatly facilitated cat retrofitment.
Here we get a look at the hardware, and although the artist didn’t quite completely grasp the point—they drew a choke plate; none would be needed, and there’s no choke on the actual car—it does show how the injected fuel would hit the ultrasonic plate. The underhood photo shows a stock ’72 Slant-6 air cleaner sitting in its factory-intended location, which implies even this handbuilt prototype with big, klunky components available at that time fit within the original packaging and allowed the hood to close.
This final page talks about work being done on the subject by others. Dr. Thatcher received about eight patents in the field. None of this stuff was ever commercialised, as far as I know. That’s a shame; this looks like it was a really good idea. Perhaps it’s a pity Thatcher didn’t work for Carter or Holley or Stromberg or one of the automakers.
I know nothing about ultrasonic fuel systems, but I know those ultrasonic humidifiers were impossible to keep clean. Scale was a problem (as seen in one photo), but so were mold and that orange bacterial film you sometimes see in the nether regions of office water coolers; which is why I avoid those.
Almost daily thorough cleaning was the only way to keep these things clean; and all the nooks and crannies made the job nearly impossible. We finally gave up on them for that reason.
Huh. Scale was definitely a thing, and that cleaning brush they took the trouble to include (with its own little holder!) was a useless joke, but periodically running the humidifier for a little while with citric acid solution in the chamber (nozzle removed and hole covered) easily cleaned it up. We never saw mould or bacterial film in them. Different water…? We were just using Denver tapwater.
A search of SAE papers suggests there was a flurry of interest in ultrasonic atomizer fuel systems in Japan in the late ’80s and early ’90s, apparently chiefly by TONEN Corporation (formerly Toa Nenryo Kogyo). Whether anything came of it I have no idea, but it appears the concept wasn’t completely abandoned after this.
H’mmm! I happen to be in the middle of filling a(nother) shopping cart with SAE papers before my annual allotment runs out. Probably already got too many, but now you’ve given me another search to try. I wish their search engine were even a little bit more functional; I’ve never found a way to specify that results must contain both (or all) specified words—it always gives a giant list of results that contain any of the specified words.
If it’s any help, here are the DOI Numbers.
These are the Japanese papers, most but not all of which are from TONEN Corporation.
Here are the two more-recent Indian papers, both from Indian Institute of Technology Madras:
There’s also a 1984 paper from the New Jersey Institute of Technology, describing a series of experiments on a 1968 Ford six fitted with this type of system:
This 1978 paper also has some foundational discussion of fuel atomization and fuel films on combustion performance:
Hey, thanks for these. That ’84 paper’s abstract says:
The 1989 Japanese paper (emphasis added because the cold-engine question came up elsewhere in discussion of this post):
The 1991 paper:
The 2020 Indian Institute of Technology Madras paper:
The 2015 Indian paper:
A third, 2018 paper out of the same Indian institute:
So yup, the idea is valid, but nope, that’s never enough on its own; its commercialisation could easily be scuttled by any number of real things—no conspeercy required.
I looked through the 1989 paper (and yes, in that one, SPI = single point injection), and it remarks that atomizer durability had been a sticking point in making it work reliably enough for production.
Their test data for a 2.0-liter SPI engine of unspecified origin shows advantages with the ultrasonic atomization, but at a glance, they seem incremental, and it’s not clear how applicable they would be to a multipoint injection system.
I could easily see the combination of those three factors being the commercial downfall of the idea. Single-point injection had a relatively narrow window of utility — it was a little too expensive to completely replace carburetors in the ’80s, and as emissions requirements tightened beyond that, most automakers went to multipoint injection — and the cost and difficulty of making the ultrasonic horn durable enough and reliable enough for use on passenger car and truck engines may have exceeded its benefits.
I’m suspecting that to get the benefits of the finer atomization with multipoint injection would require separate ultrasonic horns for each injector, and I can see that being a practical limitation as well.
This does indeed look very similar to the TBI setups popular in the 80s and early 90s. While not a true port-injected setup, these TBI systems still offered definite improvements in drivability and efficiency over carburetors. And no pumping the throttle before starting!
I don’t consider 4-6% improvements in MPG to be trivial, and I doubt manufacturers did either, not when at the time they were scratching and clawing for every tenth of an MPG they could find to meet CAFE standards.
Four to six per cent is trivial compared to the 22- to 28-per-cent improvement measured with the tested ultrasonic system, though.
Always look forward to your very interesting, eclectic, and regularly offbeat writing topics Daniel. You must be considered one of the world’s most authoritative experts on all facets of the Chrysler A-Bodies, and any experimental technology applied to the Dart and Valiant. Great work, and a fascinating read, as always. I wonder if sub-zero winter weather, would have impacted the atomization of the fuel.
I too enjoy exploring the vintage ‘What’s New’ section of Popular Science. Without seeing the date in the page footer, I was easily able to pin this page to 1985, based upon the technology shown. $5,000 for 800k of memory, a 9 inch monitor, floppy disk memory, an inferior inkjet printer, in a 25lb. package. Doubt, the user could save to the hard disk either. Utter insanity! Well, at least it had a Unix operating system. I remember as a graphic design student, being forced to buy a Mac SE, stretched screen monitor, and a primative inkjet printer, for around $3,200 Cdn. in 1987. As Apple was the only operating system that Adobe made graphics software for. PCs used Corel then.
Thank you for this!
I don’t remember where I read that a fuel fog like this is much less prone to manifold-wall condensation even down to low temperatures, but I think I did. I think some degree of mixture enrichment would’ve still been required for cold starts, though, (especially given what passes for “cold” in Florida).
Yes. Though it’s not an entirely correct analogy, thinking of how an ultrasonic humidifier breaks up the water thoroughly enough that it doesn’t sink to the floor and make the carpet damp in front of the machine like the conventional water slinger humidifiers tend to do, is part of the equation. While fuel will still condense on cold surfaces like condensation forms on an iced drink, the ultrasonically atomized fuel will stay suspended in the air for a longer time than the larger droplets produced by carburetor Venturis. This would certainly minimize the amount of fuel that collects on cold surfaces or precipitates out before the intake manifold comes up to temp.
Another proof of the efficacy of this setup is the mention that diesel fuel could be sufficiently atomized so that a two stroke spark ignition engine would run adequately on it. That’s impressive!
As a matter of fact, it had HP-UX in ROM and booted to a Pre-X GUI.
And no, no hard disk, just one 800k floppy.
Once again we thank John Greenleaf Whittier: “For all the sad words of tongue and pen the saddest are these: It might have been.”
From what we can see here, this looks like a tremendous missed opportunity. Of course, once automakers got done cutting costs from the system and mounting the delicate electronics somewhere in a zone of heat and vibration (like, say, the air cleaner of a V8) we might have ended up with a variation on Chrysler’s Lean Burn.
But maybe not – perhaps it was just about patents or, as you say, where it was (not) invented.
We’ll never know. But it does seem, at least per this report, to be basically different to another branch of this general kind of exploration in the mid-late ’70s/early ’80s: a guy devised a carburetor, named it after himself, and self-promoted it loudly enough that stuff happened. Reliably-documented pieces of the story include Holley building a prototype and EPA methodically testing it with lousy results nothing like dude-guy’s own rosy results. Less well documented is how these pieces fit together; there are rickety web pages making the predictable claims—Holley bought out dudeguy and deliberately made a rotten prototype to kill the idea, etc.
US and Japanese automakers trying anything to avoid more expensive high pressure port EFI, and probably German patents.
My nature is to be skeptical when I read something like this. It reminds me a bit too much of those miraculous 100 mpg carburetors. Well, obviously, this is much more grounded in science and reality than those, but whenever I hear of something like this that offered such an almost miraculous improvement in emissions, at exactly the time when all manufacturers were desperate to find effective ways to bring them down, yet they didn’t pursue this approach (except in Japan, apparently, to a limited extent), I can’t help but wonder why.
From my limited understanding of things, I’m a bit skeptical about the actual benefit of the ultrasonic aspect of this, and am inclined to believe that the main (or all?) benefit came from the electronic fuel injection system. I did a bit of reading about the atomization of gasoline in IC engines last night, and it seems that carbs can be quite effective in that process, especially in a steady state (engine load/rpm). A carb can be tuned to provide an optimal mixture under those circumstances. The biggest single issue where carbs initially had problems with meeting the early emission regs was in the transitional states, which of course are extremely common in cars, especially in city driving.
The biggest issue is that when the throttle is opened, the accelerator pump squirts a substantial stream of liquid gas into the carb, more than can be properly atomized, and leads to pooling of raw gas in the intake manifold bottom or clinging to the manifold walls. FI resolves this issue, especially so with an effective electronic feedback system, such as employed here.
Obviously, TBI systems similar in concept to this (minus the ultrasonic element) became near-universal some years later.
I can’t help but think that the atomization aspect provided by the ultrasonic device would have been adopted by manufacturers had it really been such an effective device. Why wouldn’t they? I know your answer: because they were such dummys with their heads up their asses.
With so much at stake, I just can’t quite buy that argument. And I don’t agree with your claim that Jan Norbye’s reporting was always sloppy and half-assed. PS wasn’t exactly an engineering journal, hence the title of the magazine. I don’t see anything sloppy and half-assed about this article. The problem is: when authors like you make claims like that, it tends to make me skeptical of your claims. How would you have known about this device if it hadn’t been for Norbye’s sloppy and half-assed report on it?
Looking through SAE paper abstracts, it seems like the idea of ultrasonic atomizers pops up every couple of years. Recently, for instance, there were a couple of Indian papers describing a device very much like the one in the article for motorcycle use, and an interesting-looking one about using ultrasonic atomization for water injection in diesel engines. There’s also some stuff about nanofluids and the utility of ultrasonic atomizers for evenly dispersing them.
I don’t claim to have read any of these papers (I’m just clicking through abstracts), but simply by the patterns in development interest, it seems like a concept that periodically attracts attention because of the potential advantages of more complete/uniform atomization, but that for whatever reason ends up not quite making it, either because of technical issues that haven’t been solved or because it’s not enough better than the available alternatives to make it to production automotive applications.
I have mixed feelings about Jan Norbye, who produced some valuable reportage, but also is responsible (along with Jim Dunne; I have no idea of their division of labor) for one of the more jaw-dropping factual errors I’ve seen in an automotive history. (Not so much the magnitude of the error, but the context in which it was made multiplied by the degree to which it was obviously and verifiably wrong.)
These other and repeated efforts support my gut response: that it wasn’t adopted because the Big 3’s engineers are all dumb asses, but because of legitimate issues/limitations of one kind or another.
So what “jaw-dropping factual error” was that?
Sure, both of these guys were just journalists trying to maximize their income but churning out articles at high speed. I’m not surprised they made some mistakes along the way. I know I have, and I don’t pretend to have either an engineering or journalism background.
I take things at face value and apply my own BS meter. If anything, Norbye is more sucked in by this device than he should have been: “It may well be the answer Detroit has been looking for since the EPA came into being.” How many times did we hear that in the 70s? Or other decades?
The jaw-dropping factual error, which is repeated in both their late ’70s Buick and Oldsmobile histories, is the assertion that the Dual Path Turbine Drive and 61–5 Hydra-Matic used in the Special and F-85 were different names for the same transmission, which they describe as the three-speed Hydra-Matic.
The reason I use the term “jaw-dropping” is that for those books, they interviewed a bunch of Buick and Oldsmobile employees, reviewed factory data for sales figures and price lists, and in at least a couple of cases pretty obviously examined the applicable SAE papers. The transmission chapters of those books contains various anecdotes about the development of other transmissions like the assorted Dynaflow variations. And yet they still made not just a small mistake, but quite a large one — even a casual glance at a diagram of either of those transmissions reveals that they’re not even similar, and just looking at contemporary brochures or their own past road tests would have made clear they were different, at least to the extent that one was a two-speed and the other was a three-speed.
If I had seen that mistake in a tossed-off remark in an article about something else, or in a work by someone obviously less familiar with the cars in question (e.g., a British book about Rover talking about the GM predecessors of the Rover V-8), I would have just shrugged, but it was a bizarre and elaborate error to make in those books, and it leaves me wondering what other mistakes they may contain that I haven’t noticed.
That’s pretty bad.
Given their huge output of articles and books, I strongly suspect they had one or more assistants on these book projects, and perhaps that’s where it came from? But still…
I have no idea. They present a variety of technical specifications for the supposed common transmission, so it’s a uniquely elaborate error, not just a typo or a tossed-off misstatement. It’s comparable to interviewing a bunch of Chevrolet engineers about the development of the Corvair and then asserting it had an inline four-cylinder engine.
I worked at the EPA emissions lab in Ann Arbor during that time. When gas prices first spiked, we saw many concepts and devices from inventors that were going to revolutionize emissions and fuel economy. None of them ever panned out. I still see some of those concepts on eBay today.
Ooh, neat! I used to drive by that facility all the time. I bet you’ve got some great stories.
Fair point, for sure. It reads to me like it’s 1:30 AM and this article is due an hour and a half ago and I must sleep and I need something that passes for a flourish to end it more than any indicator of sucked-innedness.
Yup, claims like these just about always warrant deep skepticism. This one nudges out of that category for me by dint of having been developed by legitimate; credentialled; well-employed engineers (not some guy in his garage or hut), and tested at a legitimate, EPA-accredited lab (not the same guy scribbling numbers on a pad of paper in his lap as he drives).
Automakers were dummies with their heads up their asses? Not my words; I said what they did and what they didn’t do.
As to Jan Norbye, though, I stand by my opinion. Yes, of course I’m glad the article got written, but writing an article like this without mentioning driveability can only be described as halfassed. Even if he didn’t get to drive the car himself, even if he specifically excluded anything the system’s developers claimed, surely the subject came up in ways accessable to him when he was researching for this piece. I’ve seen the EPA-format reports those test labs generated when they ran these kinds of tests, and they always include at least cursory descriptions of the vehicle’s startup and running characteristics. I might not have carped about it if this weren’t a pattern with Norbye. Elsewhen, he slagged the Torqueflite as an inferior transmission because it lacked water-cooling for the fluid. That’s just wrong; it’s lazy reporting. In 1966 he said the Slant-6 was obsolete because it had only four main bearings, and around the same time he said “today’s drivers prefer warning lights rather than gauges”. Of course he’s welcome to his opinions, and those two might be at least theoretically arguable, but he presented them as facts.
Over the years I’ve read quite a lot of his stuff, and it seems often marred by that kind of sloppiness and omission and error. Me, I’ve certainly gotten stuff wrong and left important stuff out of articles I’ve written, but I think I’m a bit more careful about trying to get it right.
Even port injection engines will tend to form fuel films on the inner surfaces of the combustion chamber, on the surface of the piston, and around the exhaust valve, which is apparently a principal source of hydrocarbon emissions on modern engines. (HC emissions are much lower now than they were in the seventies, but not nonexistent.) Finer atomization reduces that, which is helpful, but it seems like the ultrasonic approach would be harder (and more expensive) to achieve with multiport injection, maybe not possible with gasoline direct injection, and probably not as much of a priority in terms of emissions control these days.
Totally agree for automotive applications. Some of those papers you dug up suggest small-engine usage, though.
The Indian papers certainly seem to be focused on trying to clean up scooter emissions, specifically.
I don’t blame them!
Interesting approach, but I think given the time frame (1972), it was never going to provide any impressive results. TBI only became effective when the computer control module was developed, as it enabled the IC engine to operate at the stoichiometric ratio needed to minimize emissions and maximize fuel economy. That didn’t really start to occur until the early 80s. Although patented, a patent in itself doesn’t guarantee success.
From Wikipedia, Advanced Patent Technologies, mentioned in the article, has an interesting history itself. It was noted for patents not only in the ultrasonic fluidic fuel system for combustion engines, but also for an ultrasonic endodontics device, an ultrasonic meat tenderizer, and an ultrasonic dry cleaning machine. Now called Bally Technologies, they focus on gaming technology.
Look at the results on page 1. How are those not impressive?
I think ultrasonic technology ended up in some inkjet printers, although piezoelectric was and is the majority solution. I can forgive the Europeans for not adopting this because they had already thrown in with Bosch, and K-Jetronic was good enough to meet pre-1980 standards without a catalytic converter in some applications. Detroit should have looked harder because this beats a computer controlled carb 9 ways to Sunday
On a related note what ever happened to pneumatic fuel injection like the Orbital 2 stroke?
Interesting article as always, Daniel. Your tech articles are among the most engaging on CC.
I too messed about with humidifiers in my youth. It usually involved some sort of toy car or other vehicle getting misted in the cool fog.
There were cool mist humidifiers prior to the ultrasonic models. Before central whole house humidification systems started getting traction in the ’70s, there were myriad evaporative wick humidifiers that used a fan blowing at a wet wick or filter. Interestingly, they are still made, you can find similar looking Vicks branded tabletop cool evaporative or ultrasonic humidifiers on Amazon, both priced at $50.00.
The advantage of ultrasonic boils down to (cool mists to?) they are quiet. But, the white noise from the fan based units is sort of pleasant to me. The ultrasonic also produces a bit finer mist, it could get a bit damp around an evaporative unit.
Some of the evaporative units were quite large – plastic walnut cabinet floor units designed for large areas, others a bit more compact.
More common were Hankscraft and DeVilbiss units that were usually placed on the floor as they had fairly good sized water tubs.
We were a Hankscraft family, lots of fun in the late 1960’s.
We had one of those Hankscraft units when I was a kid; I believe it was purchased about the time I was born in the late 1970’s. I remember being a bit freaked out by it when I was about 3, as it looked like some kind of cyclops monster spraying water mist while making an eerie whirring sound.
I had exactly the same spooked reaction to exactly the same vapourizer at exactly the same age.
I preferred the magnets you put around the gas line into the carb.
You know, as once sold by JC Whitney and others.
The concept of aligning all of the gas molecules in the same direction; brilliant!
Never wears out, and transferable to any car with a carburetor.
When I worked at the DOT every once in a while someone would show up with a device that would save fuel. The worst ones to deal with were the ones that caught the eye of a politician or a bureaucrat.
One was powering our diesel powered units with a mixture of water and diesel fuel. The only modification needed was coating the piston crowns with a catalyst material. IIRC the mixture was something like 60% diesel & 40% water. They had a special blending machine that was supposed to blend this mixture so it wouldn’t separate. Mileage didn’t improve much if at all, may have actually dropped but you were only burning 60% of the fuel! Supposedly the water was supposed to flash into steam react with the catalyst and split into oxygen and hydrogen to enhance the combustion of the diesel fuel. I remember this one particularly because of the audience we had for this one. We had cleared out half of the parking garage and had portable bleachers brought in for the crowd. Nothing came of it. I suggested if we were going to test this it would need to be done on a truck out of warranty coverage. That threw it out to the districts and there wasn’t any interest. Couldn’t imagine using it in critical equipment, winter operations? How quickly would the water/fuel mixture separate? Supposedly there were a few busses running on this stuff in southern California. Never followed up.
Another was the “turbulator”. This was a piece of sheet metal that was installed in the air intake piping after the air cleaner. It was bent up and was supposed to spin the air up into a turbulent flow. Supposed to aid combustion. OK, maybe that works, a bit, possibly, on a naturally aspirated engine. I don’t think the turbulent air is going to survive passing thru a turbocharger followed by a trip thru an intercooler.
The cure for this was a memo stating we required an SAE fuel economy test performed by a third party testing lab, that usually stopped them dead in their tracks.
This is the most interesting discussion I have seen yet on Curbside Classics. Thank you all for your learned contributions. The ultrasonic technology is interesting. Has its time passed, or is it still relevant? I was very impressed that it allowed spark ignited diesel fuel two stroke operation. A huge problem for clean two strokes is that the time available from closure of the exhaust port (or valve) to ignition is very short. A gasoline direct injected (GDI) four stroke has maybe four times as much engine rotation allowing much greater mixture. Despite that GDI still suffers from high (for a gasoline engine) particulate emissions. Another issue with GDI is high pump pressures and the cost of the pump and energy to drive it.
Closer to my heart is two strokes, and I wondered if Rotax/Bombardier or Arctic Cat had looked at ultrasonics in the creation of their GDI two strokes. The Bombardier ETEC seemed similar with their speaker coil like fuel injector. What is going on with Orbital? As I remember Orbital used a blast of compressed air along with the low pressure fuel injection to achieve a reasonably efficient (for the time, 1995?) low emission combustion. Could this/would this be integrate able?
As to further speculation, I wondered if the lessened likelihood of condensation on the manifold walls was due to the ultrasonic adding energy to the air fuel mixture vs the carburetor evaporating fuel thereby reducing the temperature of the mixture thereby getting closer to the dew point.
Judging by the above-noted papers, I’m going to say no, although what you describe IS the reason for manifold heat risers. The beneficial effect of the ultrasonic horn stemmed from finer atomization of the fuel: much smaller and to some extent more uniform droplets.
It seems like the ultrasonic horn would still have value for port injection applications, but they would probably require a separate horn for each injector, and the technical papers make me think the cost would probably exceed the practical benefits. The TENSO papers also suggest that durability had been a problem; obviously, a running reciprocating engine is not a comfortable environment for delicate components. I’m not sure how technically feasible it would be for GDI.
The Indian Institute of Technology Madras papers, which were the most recent discussion I found among SAE technical papers, were proposing using an ultrasonic atomizer with a single-point electronic injection system for scooter and motorbike engines in place of carburetors. Given the popularity of scooters and other small engine light vehicles in large urban areas in India, I imagine that would provide a meaningful improvement in emissions, even though single-point injection is long since obsolete for passenger cars and light trucks.