Smokey's Adiabatic Engine 6

[SBBlue]

Somebody in another discussion thread made a mention of Smokey Yunick's adiabatic engine. I had never heard of it before, and did an internet search as well as retrieve the patent and dug up some old Popular Science magazines that discussed it.

For those of you not in the know, Smokey Yunick was a legendary race car mechanic and Popular Science correspondant. He died a couple of years ago. In March 1983 Popular Science carried a story about an engine he had developed that only had two cylinders and 78 cubic inches but developed 150 hp and got 60 mpg when installed in what looks like a Volkswagon Rabbit. He called it his "adiabatic engine." Supposedly all sorts of car companies were quite interested in the engine.

A followup story done in Popular Science in November of 2000 stated that the "engine came close to going into production with General Motors several years ago, but the deal hit a stalemate when patent owners couldn't agree on details." If you visit the patent office, you will find that the patent covering the engine (US 4862859) was allowed to expire in March 2002. (Web site for patent:

http://patft.uspto.gov/netacgi/nph-...&s1=4862859.WKU.&OS=PN/4862859&RS=PN/4862859)

In reviewing the patent it appears that Smokey's engine used an "afterheater": coolant heat was used to vaporize gasoline, and exhaust heat was used to heat the air/fuel mixture coming from a turbocharger compressor to 440 deg F. In the cylinder the air/fuel mix reached a temperature of 1600 deg F before ignition -- all without detonation.

According to the Popular Science article, the reason for no detonation was "Smokey's Secret".

After reviewing some of the numbers provided in the Popular Science article and in Smokey's patent, I've been able to deduce the following about the engine;

1. The air/fuel ratio was something on the order of 22:1 to 27:1.

2. Peak combustion temperature was above 5000 degrees F.

3. Exhaust gas temperature (before the turbocharger) was about 2200 deg F.

4. Assuming no loss of cylinder heat to the cylinder walls (i.e., an actual adiabatic engine) the best possible efficiency was about 38%. If the engine used a Miller cycle modification, an efficiency of 48% would be possible (no mention was made of the Miller cycle)

My conclusions:

1. Smokey may have been able to get the engine to work, even though there was a high intake temperature, by using a very lean air/fuel mixture to prevent detonation.

2. There was no way that this engine was developing efficiencies of 50-60%.

3. It is doubtful that the engine, as described, would last long because of extremely high temperatures. With the claimed fuel flow and intake air temperature, the peak combustion temperature would be over 5000 deg F, as compared to perhaps 3500 deg F for a normal spark ignition engine.

4. I find it very hard to imagine that General Motors was ready to put the engine into production and didn't only because of patent royalty issues -- only to have the patent abandoned several years later.

==============================

Comments, anyone? Did anyone ever actually see this engine, or hear anything about it?

 

[strokersix]

Piston rings are a significant path to conduct heat from the piston to the cylinder wall. Reducing the conductivity of the rings would increase piston temperature. Whether this is desired or practical is another question entirely.

 

[jmw]

Paper Cups!
You guys need to credit the right people here. Using tree bark to make a container to boil water in has a history going way back before the plastic cup. Native Americans, (among others) speak out!
(not sure if there is a particular bark to use, large leaves should do just as well.)
Sorry to intrude, I'll get back to just reading the thread since i have nothing useful to contribute.

 

[TChronos]

I tried to find this BS product at the speed shop. They offered me was WA, apparently an alternative product:

http://www.jtc-nj.com/C4a3.jpg

I can only hope it's as effective.

Back on topic: If you use ceramic heads, valves and pistons, the rings become a major failure point, because there's no place for the heat to go. I read some research on this someplace, I'll see if I can dig it up.

 

[SMOKEY44211]

The way I understand it was that the ceramic coatings, in particular on the exhaust valve, insulated it enough to lower the detonation threshold enabling a higher compression/expansion ratio. EGT was in the neighborhood of 900 deg F. at WOT. Ceramic coating the compression ring was an exercise to possibly eliminate the need for lubrication. Last I knew was the only thing that made it into regular production was the turbine blade of the turbo charger(homomgenizer). If memory serves me correctly this was picked up by Garrett.In the absence of varifiyable #'s I think in the end it was no better then a diesel.----Phil

 

[rmw]

In my humble opinion, (I have to say that for the lawyers benefit, don't I, ask Klick and Klack) most of what you read in popular science is bunk, isn't it? Should be called popular science fiction. This is my contribution to this thread. I enjoyed the read very much. Thanks to all who contributed.

 

[noj]

Yep I have seen the hot cyclic engine of smokeys, seen it
run. It sounded a little like a lawnmower engine until ya
put the fuel to it then it sounded more like an airplane engine. He drove it back and forth accross the seabrease
bridge every day to and from work and accasionaly to a little cafe for a cup of soup. Smokey told me Gm had some
concernes as to heat sink he was confident that wasnt a problem but wasnt gonna tell them "a god damn thing untill
those pelicans get with the program" Later around 1991 0r
so I was down to see him and he had the engine out and ready
to take it apart to see just how it endured. Later he called me about something and I asked him about the engine
All he said Its damn well do able. This much I know about
about Smokey if he said it was so ya better bank on it. because it was so.

 

[SBBlue]

Looking back over Smokey's design and claims, it strikes me that it has some resemblence to a HCCI engine -- homogenous charge compression ignition engine.

First, a homogenous charge refers to mixing the fuel with the air quite throughly and heating it to promote vaporization -- prior to introducing it into the cylinder. What was Smokey's compressor -- a "homogenizer", and the fuel was preheated.

Second, the air/fuel ratio was quite lean -- at least for a spark ignition engine.

Perhaps I should start another thread on "Smokey's HCCI Engine"?

 

[dopieop]

Thoughts of a Shade-Tree Mechanic, [another 5/25 Gemini], re: Smokey Yunick's Adiabatic Expander Cycle ICE.
Everyone seems to be very positive that the thing just can't work. Their usual reasoning seems to be that it MUST detonate like a grenade because you're putting that A/F mixture in at a gazillion degrees F or C, or maybe K.
I seem to remember ol' Smokey stated he used a "Special" cam, and that the intake charge was at (X) degrees 'at' the valve.
I don't recall that he said it was at (X) degrees when it was in the cylinder.
I also recall something about a drop in temperature when a high pressure gas flows into a lower pressure region through an orifice.
Gee, what would happen to Smokey's pre-heated mix if he waited to open that intake valve very late, and then only opened it a wee bit?
Sounds almost like my previous statement, doesn't it?
The rest is tres' simple, recycle the heat instead of flushing it down the pipe, use high compression and long rods, and voila', HP with minimum fuel.
My only real question is: When will some enterprising investigative bloodhound trace the ownership of the Patent?
Who is at the top of that Food Chain? Are Big Oil and Big Government hand in hand? Did Smokey's Motor hit at the wrong time in History, right after the major auto makers had pulled the Computer Engine Control/You must have Fuel Injection for economy/Lean-Burn actually works SCAM?
Imagine the egg on the faces of those who perpetrated this Hog Wash, [especially at the next Stockholders Meeting], if a little ol' guy from Daytona invented a motor that REALLY was efficient!
But I ramble and digress, it's Hell getting old, but sure beats the alternative.

 

[SBBlue]

The patent was actually abandoned a year or two ago.

For a patent to stay in force 18 years it has to be renewed every few years, which basically means you have to send the patent office another couple hundred bucks.

Nobody sent in any money to renew Smokey's patent.

 

[patprimmer]

If you open the inlet valve real late and only slightly, the partial vacuum you creat will drop temps, but the increased compression ratio will only bring it back again.

Also, it will really kill power, which will need a larger engine to give enough power, which will kill economy, as it will be heavier, have a little more friction, and have more surface area to loose heat through.

The only benefit of preheating fuel is better evaporation, leading to more complete and possibly faster combustion.

Incomplete combustion is not a problem worth mentioning in a modern engine, but increased burn rate might allow later optimum ignition timeing, causing less pressure build up against the direction of rotation when near TDC, and more of the energy could be used for the power stroke, that is providing you actually got faster burning.

Regards
pat

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[blur]

I think Smokey's whole point was to reuse heat for power rather throwing it away in the exhaust and cooling system. However, it seems to me that if you actually wanted to make USE of this waste heat, it would have to be put back into the engine during the power/combustion storke-not the intake stroke.

I know a lot of industrial turbine engines will reclaim waste heat, but they will add it AFTER compression, and before combustion and expansion. There isn't much time or space between the compression and combustion cycles of a piston engine.

 

[kiwinjuneer]

Sorry to be a little late posting but wanted folk to be aware that the Mitsi GDI engine has a mapped ECU and I understand, achieves a 40:1 AFR at idle dropping to 22:1 at cruise. Not sure about WOT but assume AFR would reduce to close to stoichiometric for maximum power.

Presumably the very high injection pressure results in better atomisation of the fuel (= better kinetics) plus the ability to aim the charge in the direction of the s/plug, enables stable running even at these very high AFRs. We own two vehicles (L4 and V6)with GDI engines and can vouch for their fuel efficiency.

 

[Gotitrunning]

Actually guys it did work I drove Delorean with one in it in the 80's and Smokey's personal car,a Ford Fiesta,had one it in it for over 15 years. The item that you are all missing is the fact the the fuel is vaporized. When vaporized the surface area of the fuel is much greater thus making a faster not slower reaction, try it.

Also the deal behind the big industry boys goes like this Smokey thought that to get the engine accepted by the big industry guys a try it would be good to give ,I believe 20%, of the engine rights to a past Ford/Chevy CEO named Knudsen, it turned out that no one really like him and he was a deal breaker in many cases. The big industry guys also wanted Smokey to do all the work and not pay him what the thing was worth! Also Smokey finally bought out Knudsen's share of the motor and the motor was scheduled to go into the Delorean car, but we all know how that ended, this is in the Delorean history books!

For all of you guys who say Smokey was a cheat and fake then why did Hudson, Pontaic, Chevy, Ford, General Dynamics, Autolite, Unical, the list goes on and on hire Smokey as a consultant? Ever here of a flow bench? A Dyno, Variable Power Steering, the list goes on and on, they are all Smokey inventions. Oh ya, if you want to see a Smokey Hot Vapor engine run they got one that works at the University of Central Florida in the basement. They dont advertise it but go see for yourself, room B119.

Ryan Bailey

 

[Gotitrunning]

Forgot to mention that Ferarri ran almost an identical engine setup in the 2001 Indy 500 and did very well.

Also if you don't believe that the big industry guys would let the engine go do a BTU conversion on gasoline and hydrogen. Think about this: hydrogen in a gaseous form the container for 9/10's a gallon weighs 90 lbs, a cylinder, a container to hold twenty gallons weighs as much as some small cars! Ok, take it in a liquid form, in the most expensive container you can get and cool it to say 350 degrees F below 0, that container still loses 1% a day. The container in the moon lander lost 9% a day! The shelf life of gasoline today is around 90 days, that is to get from the refinery to your gas tank, hydrogen would be the same, unless you somehow made it yourself from water, VERY EXPENSIVE! So you guessed it you lose about 90% in the pipeline! How many times you gonna have to fill up that Hydrogen powered car to go anywhere? GM is wasting billions on this scheme just because of publicity. It can't work unless you plan on paying 5 bucks for the what would be like a gallon. This was all taken directly from Smokey's notes.

 

[Gotitrunning]

Oh ya, I am not a materials or thermo guy but Smokey told me that one of the most important things about his engine was that when you vaporized the gas it evened out the octane rating or made all the gas the same. He said that in a gallon of gas the octane rating could vary by 20 points. Just something I remembered.

Ryan

 

[patprimmer]

Variable ratio power steering was developed and patented bt aebishop manufacturing in Sydney Asutralia.

Regards
pat

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[jmw]

By the way, Metalguy. You commented on not wanting the ignition point at TDC. I beleive there is an engine under test where the piston is in two parts with the cwon separated from the main part by a spring so that at ignition the spring is compressed, storing energy that is released later in the cycle. I don't know who designed it or what's happened to it. Last heard it was being tested.

 

[kiwinjuneer]

IMO and from a position of ignorance, three things killed Smokey's engine:

Smoke (or photochemical emissions) in the form of NOx because this forms in a certain time/temperature regime that would seem to have been present in this engine.

Durability. See comments above.

Safety. There would have been lots of HC vapour around and how is the latent heat from the engine when it is turned off, dissipated without creating more HC vapour?

Heating the fuel will definitely REDUCE theoretical efficiency if it is (erroneously?)assumed that complete combustion is achieved during the power stroke. What is very interesting though, is that getting the fuel fully vaporised and right at flash point will reduce the ignition delay and make possible the more efficient extraction of the available energy within the milliseconds available while the pistion is descending. It would seem that this is where the benefit mentioned above, comes from.

I trust that one of you clever folk will throw some efficiency numbers at the vaporised fuel Vs droplet fuel (incomplete?) combustion situation. Me? I'm going to sit on the sideline again...

 

[kiwinjuneer]

Me again

SBBlue mentioned some efficiency figures and I totally agree that unless there was some type of combined cycle functionality we dont know about, Smokey's 50% claim is OTT.

But I would think that a major factor still has to be ignition delay/rate of combustion and understand that they are not considered in theoretical efficiency calculations are they?

 

[carnage1]

there was one other piece of the engine, besides the reduced heat loss increasing efficiancy his design with the homogeniser reduced pumping losses.
the engine had to run a special aircraft oil to withstand the tempatures acording to an article I read a while back.
I think that the secret to the whole thing was using a lot of egr as well, whatever the other piece was it was supposedly very simple and it had to be someting easy to hide like putting the egr stuff in the homogeniser unit.