6-stroke engines

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kilcoo316
kilcoo316
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6-stroke engines

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After the combustion and exhaust strokes, the cylinder is still ultra hot, so water is dumped in, this quickly expands to steam, providing a 5th powered stroke and also cools the engine.


While it obviously could be used in "the real world", I wonder would it find an application within F1? The weight trade off between water and radiators...


http://www.autoweek.com/apps/pbcs.dll/a ... WEEKSISSUE

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NickT
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Location: Edinburgh, UK

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Very interesting, I wonder how long it will take one of the big boys to pick up on it :?: I bet Recardo would do an excellent job in developing a properly tested prototype very quickly :idea:
NickT

Mikey_s
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What a good idea - it seems too simple (but then again most of the good ideas are). I can see some formidable engineering challenges - but I very much like the neatness of the concept.
Mike

Nick
Nick
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Joined: 12 Mar 2006, 08:52
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You would need to carry around 20+% of the weight of your fuel in water to run a 6 stroke engine, and that wouldn't count towards the 600kg minimum. I don't see how the perfomance gains from such a cycle would offset the extra mass of water onboard as well as the fact that the aero would be compromized increasing the cassis volume to accomodate it.

se7725
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Joined: 24 Dec 2005, 07:15

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That is true, Nick, but there would also be a reduction in cooling needs which could increase aero efficiency and allow for a lighter cooling system

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joseff
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Joined: 24 Sep 2002, 11:53

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I'm not a materials engineer, but I'd imagine there's a thermal fatigue limit? You can only put so many heating-cooling cycles into an engine before something warps out of place.

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Ciro Pabón
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I agree with se7725.

Nick_T, we could say also that the 20 or whatever percent of water is not only for cooling: it is steam for power. You will get a reduction in fuel weight given by the ratio of gas to steam power. As implied in the article, you would get a cooler engine with the thermodynamic improvement this imply. Besides you could joke about steam-powered F1s... :D

Somehow, this thing reminds me of the Miller-cycle engine. Miller engine claims 15% improvement in hp by tweaking the Otto cycle in a supercharged engine. But not in my F1, no sir!

Actually, like all good ideas I have seen lately, this has little chance in F1. I would say everybody is terrified of radical changes or garage inventors: a championship, like F1, demands gradual changes.

No team can take freely the punch a real new development means. Today, few teams would dare to try the radical ideas of the 80's: it would be too great a penalty in the championship and a hit in sponshorship.

F1 needs mature ideas from the auto industry, I think: F1 has become professional in the last 20 years. It is clear when you see the grid and recognize only major Euro-japanese carmakers.

I dare to say that F1 cars have changed from prototypes to extra-super-luxury factory cars.

And Joseff has a point, BTW. But I see it also a little fuzzy (don't I always do it?), because you may have greater changes in temperature and thermal stresses, right, but the materials have higher stress module because they are cooler.
Ciro

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joseff
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Ciro, you've mentioned Miller cycle so many times now that I feel compelled to provide a production example:

Mazda Millenia
http://www.canadiandriver.com/testdrives/01millenia.htm
with a simple explanation here
http://auto.howstuffworks.com/question132.htm

From the article: "Mazda claims that the Miller Cycle engine offers more power with the fuel economy of a smaller engine, but a quick comparison of competitive 3.0 litre V6 engines in the Transport Canada Fuel Consumption Guide reveals that Mazda's fuel economy numbers aren't much better than some larger V6 engines which have about the same amount of horsepower."

is this due to lack of development? After all, it's pretty much a '94 engine, while the other cars sport new 2001 engines. Still, there doesn't seem to be much efficiency improvement to exploit.

On a side note, articulated piston systems like the one on MDI's engine viewtopic.php?p=27138 work on more or less similar principles to the Miller cycle engine(ie. "virtual" extra compression ratio), without the need for a supercharger.

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Ciro Pabón
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Well, I do not think you have to look for any other explanation: Miller engines do not claim better efficiency. They claim better horsepower, wich agrees with your post. It is logical to conclude that this extra-horsepower comes at the expense of more gas, given its design. Thanx for this nice post, joseff: it shows that there are few "free rides" in engine design, which is another reason for us to see the six-cycle engine with a critical eye.

Miller engines are another way of tweaking the Otto-cycle, that is why I found them relevant. Yes, I know I posted about them when I talked about other types of engines and the gasoline shortage, but then they also seemed relevant. I am not particularly in love with them. :wink:

I guess there are many similar ideas: for example, take a look at how you can use back-pressure in the exhaust chamber to "get rid" of valves in two-stroke engines (piston is at left, exhaust at right, red is burnt gas, blue is fresh air-gas mixture). It is sort of a "Miller-type" tweaking, but without valves and at the exhaust, not at the inlet: I wonder if this old technique is used somehow in F-1 chamber design to help the ever faster valve system.

Image

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Now, if we put this together with the six-stroke, piezoelectric injector, regenerating brakes and then, the laser spark-plug on a quasiturbine, we could .... :D
Ciro

manchild
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Joined: 03 Jun 2005, 10:54

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I like 6 stroke idea a lot. Does anyone know what is the rotation ratio between cam and crankshaft at 6 stroke engine?

BTW, there is also another kind of 6 stroke engine :arrow: http://www.ducati.com/bikes/techcafe.jh ... rt=general

RH1300S
RH1300S
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Joined: 06 Jun 2005, 15:29

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I love seeing this kind of stuff.

The steam engine is a very neat idea. I suppose you will never overheat this thing - when you run out of water the engine stops ;)

Another good lonk Manchild - that is a blindingly obvious solution. Could anyone say, would I be right in thinking that some of the limitations to higher revs be done away with. I.e. peak loads on the con-rod, 1st because there isn;t one :D second because you can control the accleration/decceleration 8)

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NickT
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Hey Ciro there is a Nick and a NickT, who have different view points.

Just in case you are in any doubt I am :twisted: NickT :twisted: sorry mate I couldn't resist an opportunity like that :lol:

Ok let’s look at the water issue. A ford focus has a 44 litre fuel tank so if we need 20% of this capacity for water for steam generation then that would be roughly 9 litres, but lets say 12 to give us a better margin. So thats a weight gain of 12 kilos plus the extra weight of the water tank, pump and plumbing :? so perhaps 20 kilos :D However this would be more than offset by loosing the water coolant - 6 kilos - plus the heavier radiator with all those cooling fins, the water pump and plumbing :shock: Not to mention the reduction in aero drag :wink:

Unfortunately we have a lot of theory but no real idea of the reality yet :cry: The potential is enormous 8) lower overall operating temperature, reduced thermal strain on valve train components, reduced emissions, increases in efficiency, not sure about power delivery yet (2 power strokes in every six, one big bang explosion and one hot steamy one :shock: ), increases in compression ratio because of the lower operating temperature and water injection during the conventional fuel/air intake stroke. Then there is the speed range of this engine, what is it :?: What happens as it moves through the rev range, will it have high outputs at higher revs like a petrol engine or will it have the higher torque output of a diesel at lower revs :?: perhaps it will give us the best of both worlds :?:

The best current production engine, in terms of a complete package with a broad power band, high torque, high power output, good economy and good emissions is the new VW unit that powers the Golf GT 1.4TSI :shock: That right its the world's first production supercharger-turbocharger hybrid system called Twincharger. For details check out http://www.autozine.org/technical_schoo ... wincharger Now let’s just think in terms of the fundamental design and innovation it has taken the motor industry to reach this panicle and how this compares to those engines that were being developed in the first half of the 20th century :?: .......


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...... apart from the evolution of the control systems for delivering the fuel air mixture and the spark ignition, and the evolution of materials there is NOTHING fundamentally different or new :shock: its still the same ol' Otto cycle :mrgreen:

Now think about this fundamental development, the six stoke engine and its thermodynamics and how they compare to those of the best 4 stroke engine :? If you can get you head around this #-o then it gets interesting :wink: Now if I was the boss of a car company or an engine specialist I would be beating my way to this guy's door :D then I would beg, borrow or steal say 25% of an average F1 engine budget to invest in tasking someone like Ricardo to do some testing and development 8)

Ciro, you are absolutely right, we won’t see anything like this in F1 for some considerable time, but that doesn’t mean we should ignore it. Remember often the best designs :idea: in this world are the simplest and most elegant ones, the ones that seem to be so obvious when we look at them that we cannot believe they had not been thought about it sooner :wink:
NickT

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NickT
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Good one Manchild another very interasting engine 8) Not sure I would call it a six stroke though :shock: it looks like a variable phased 4 stroke to me :D

I think the rotation ratio of the first 6 stroke engine would be three to one. You are opening the inlet valve once in every three revolutions of the crank. Also the article talked about exhaust valve having a double cam profile to open and close the exhast valve twice in the last two revolutions :D
NickT

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joseff
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The Motor Union 6-stroke seems to be sensible. Makes you wonder why people bother with variable valve timing in the first place. Bring it on!

NickT: IIRC there was a Toyota Corolla back in the 80's with supercharger and turbocharger.

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NickT
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there was a Toyota Corolla back in the 80's with supercharger and turbocharger
:shock: A mainstream production car :?:

I know of several earlier examples than the VW, but all were test or racing engines, the most noteable being the Lancia Delta Group B rally car. I would be very interested in learning more about the Toyota Corolla, can you post a link :?:
NickT