True odd-stroke engines are impossible because a stroke is either a decrease or increase in volume and you have to get back to the original state.

imo if its not 4 stroke then its 6 stroke at best usual 4 stroke into expansion and afterwards exhaust, the optional water injection is part of the expansion stroke.

There are two cylinders. Thus, there are 4 strokes + 2 strokes = 6 strokes, but two overlap, giving 5 stokes. The process takes 5 strokes: Intake, Compression, Power, Transfer&Power, Exhaust. "Strokes" relate to processes. This gets more complex and debatable when two different RPMs are used, such as in the engine I'm developing. The induction pistons runs at 1/2 speed, so the engine has eight strokes: Intake, Intake, Compression, Compression&Transfer, Compression, Power, Transfer&Power, and Exhaust.

no this is not a5 stroke motor, and you can get a 4 stroke single cylinder engine, i would believe you that this a 5 stroke engine but we would both be wrong@@RichardLewisCaldwell

I suppose it would be six strokes from the perspective of the fuel/air mixture.

and then you add a free-floatin turbine to the exhaust and a sterling to the heated body.

Or really just like any steam engine. There aren't exactly any cylinders that do combustion in a steam engine after all.

It's fascinating how technology goes around and comes around.

And look what happened to that

@@dancho0012 The turbine powered, Lusitania didn't fare that much better😅

And all of those ideas came from the steam engines of the time. With a small piston for HP steam and a larger one for low pressure steam. Even steam turbines work on this same principle, but with less mechanical parts.

The FIAT twin air engine is the only practical way of using an Atkinson cycle engine in a vehicle, by using it for only "part throttle".

There we go, i was wondering why this wasn't thought of before, as it's effectively just an in-block turbocharger in piston form, connected directly to the crankshaft. Makes sense this idea is about as old as the concept of super/turbochargers. It's just more power instead of more air, after all.

@@joejoejoejoejoejoe4391 Loads of hybrids use Atkinson cycle engines.

@@agt155 So to make the usual Atkinson cycle engine you have to add a generator/motor, 1/2 a ton of battery and a load of control electronics, that all add expense along with the weight. Because the valve controlled FIAT system can instantly go from Atkinson cycle to Otto cycle, it can provide both high and low power efficiently, without having to add a motor and battery for low power.

The animation shows it spinning at the same speed, or am I seeing things?

You’re right. It is “silly”. But buying rather precise parts is easier than designing and milling custom parts. The same reason the four-banger was altered to be a two-banger with a klugey re-expansion ‘cylinder(s)’.

Good idea.

They don't call it a 5-cycle engine. They call it a 5-stroke engine. Intake, compression, expansion 1, expansion 2, exhaust.

I'm not convinced this actually solves the limitations of the Miller cycle. You're going from 4 partially filled cylinders of air to 2 full cylinders of air, which isn't really allowing you to get more air when you're still moving 4 cylinders of mass around. Also, instead of over expanding within the first cylinder, you're wasting some energy going through the transfer pipe.

@@Appletank8 you are correct, however the video claims 130 horsepower out of 0.7 liters of displacement. In theory, you can use a pseudo v8 configuration with larger cylinders for some crazy power with the fuel consumption of an economy car

@@ulasgursoy2838 Is it really 0.7 L of displacement though? It's still carrying around 4 pistons of weight and friction, and it's practically unusable at low RPM. It wouldn't be that far off from a 1.4L engine expelling half of its intake. A similar engine is the 1.5L M15A-FKS, which gets 123 HP at 40% efficiency, and is usable across all regular RPMs. I'm not seeing that much advantages in this 5-stroke engine here, unless they have an efficiency chart that points out its efficiency range.

OK. Thanks for the info. So is this going to be good on all parameters for an ordinary consumer level car - cheaper, better?

Yeah I'm thinking if it "only improves efficiency under high load," then like... just make a high-revving lightweight version for sports cars, where its drivers will be happy to rev it to the moon and get decent fuel economy doing so. Economy sports cars would be fun.

Well thought out, I hadn't considered the carbon in the expansion cylinder, it would be like a gdi engine's valves not having the fuel flowing across them to clean them.

Good point. Fortunately, using a piston-topper to segregate the hot gasses from the piston allows surfaces to run above the temperature where carbon buildup occurs. “Engineering Explained “ has a good video. Search “Italian tuneup”.

I like to pull back on the old johnson from time to time, myself...

This engine only work at maximum throttle, should fitted to a race car, should see some benefits.

Exactly, this also adds a lot of unneccesary weight and moving parts needing to be balanced with even more moving parts.

Yeah, but a turbo doesn't drive the crankshaft, it just decreases the energy from the compression stroke necessary to compress the mixture to the desired compression ratio. So i don't think this engine on its own is less efficient than a conventionnal downsized turbo 4-stroke, but if you add the fact that an additionnal turbo on the 5-stroke takes further advantage of the residual pressure in the exhaust gas, you could potentialy have more efficiency. And the final advantage is the water injection : turbo and/or 3rd piston are not very good at recycling heat (as they both use exhaust pressure), whereas water injection is, making the engine even more efficient. Of course, as water injection cools the cylinder, it decreases the pressure of the exhaust gases in the 3rd piston and the turbo (thus loosing a part of their benefits), but there could still be a net efficiency gain, especially if you use highly heat conductive materials to drive the heat from the power cylinders to the 3rd, in order to recycle it more. Other ways to achieve this could be to make traditionnal turbo 4 stroke engines, but with the 2 center pistons dedicated to collect the heat from the two others (they would only be injected with air/water mix), which would then allow the motor to use the two steam pistons as coolant, instead of a pump driven radiator, and allow the water to be condensed and recycled as their exhaust would be only steam and air.

Turbines are less efficient than pistons.

Turbo relies on also putting more fuel in the combustion chamber to accommodate for the increased air density (more power => more fuel consumption). Like the turbo, the center piston uses exhaust gas and pressure difference to operate. However, this engine doesn’t need extra fuel to further assist the turning of the crankshaft (more power => same fuel consumption => more efficient)

@@oscarschott8905 while yes it is not exactly comparable, you can just use a smaller displacement engine and get the same power output.

What it's actually similar to are Miller Cycle engines. They expel a portion of the intake in order to have a longer power stroke. This ""5-stroke"" has half the intake for the same "expansion" ratio, or 0.7L of compression, 1.4L of expansion.

That's a genuinely clever idea.

I thought the same thing

I used ultrasonic fog in a TDI! 0,2 - 0,3 l water p.h. - 0,5l/100km Diesel smoother engine run better accleration less carbon pollution

​@@svendittmann3105you should have tried scotch mist.

​@@svendittmann3105what device did you use to produce the fog?

Americans are very good at "inventing" things thirty years after someone else invented them elsewhere.

🤣

i suppose they could insulate the exhaust channels and not route coolant through the center cylinder's walls

@@manitoba-op4jx yep, and egt regulated by amount of water injected

smart

Brilliant

The have one at the fountainhead auto museum in Fairbanks. It's a runner and they drive it.

So the patent would be a fake? @@bdkw1

Kinda must find it :) fountainheadauto.blogspot.com/2012/09/the-unusual-compound-automobile.html

Could be tricky to actually pull off with the limited space available over the short transfer port lengths but it makes thermal sense to me. It seems to me that the shorter the transfer track the better. EDIT: Given that the engine is already has a restricted effective RPM range I suspect that there would be an ideal transfer port length that would be able to take advantage of harmonic gas wave effects like a tuned length extractor exhaust system. That may even enable room and gas dwell time sufficient for your catalytic converter idea. The narrow usable RPM range would be likely to become even skinnier though.

To you talking about? Cats don’t add heat to anything, quite opposite it takes away heat and energy 😅

@@ddjohnson9717 the chemical reaction that is catalyzed is exothermic. Cats introduce a flow restriction though, thats where they sap performance especially because the extra heat produced is normally always completely wasted. In this twin expansion design though, that energy goes to enhancing efficiency Edit: some people prefer dogs anyway.

@@lordchickenhawk the port should be built into the head, I'd think. The catalyzer needs to be an insert that fits in place. If you are converting a 4 banger then maybe simplicity is a better option.

@@lcambilargiu Yeah, I think so too... like I said, space would be the tricky bit, either way. And the flow restriction you mentioned to ddjohnson would present further difficulties. I like your idea but I think it would be very difficult to it pull off in actual practical application.

It's because you don't just need regular water but distilled water, as using regular water with lots of impurities in it will ruin the cylinder real quick as mineral deposits starts building up on the cylinder walls.

Making the second expansion cylinder the same size as the primary cylinders defeats the point. The reason it's larger is because it requires less mechanical force to push a smaller chamber's volume into a larger one. if they were the same size, the force pushing back on the primary cylinder would completely negate any force imparted on the secondary cylinder, and you would run at less efficiency than if you didn't have the secondary cylinder at all because it would just be dead weight.

yea we still havent moved away from cast aluminum vs forged alloys... the suzuki 4 cyclinder ended up being raced...

wat

Those are called turbo compound engines, which is indeed a similar concept. A turbine uses exhaust energy to turn the crank shaft directly.

Nice idea.

Agreed, but only if you have somewhere to use that power in the drivetrain. This engine converts exhaust pressure directly into mechanical energy at the crankshaft. The turbo-style generator would first convert mechanical energy (moving gas particles) into electricity, then somewhere down the line convert back to mechanical energy through an electric motor. The added two steps converting energy may end up being less efficient, but who knows 🍻

​@@oscarschott8905 You're right, but most engines already have an alternator which could be upgraded (like some modern engines - see the Jeep Wrangler 4xe and Alfa Tonale hybrids) to a 3-phase motor generator. That also means you can remove the starter motor from the engine because the 3-phase belt-driven motor can start the engine. These motors can be upwards of 90% efficient, and I believe turbines can be similarly efficient to pistons as well while taking up a lot less space.

@@oscarschott8905 but this engine is only suitable for electric generation anyway. The additional benefit of a separate turbine generator is that you can put it after the catalytic converter to scavenge some additional heat, introduced by the reaction.

I had the same idea, but any increase in the volume of the transfer tube decreases efficiency: At the point when the transfer tube opens, you have the high pressure cylinder fully expanded plus the volume of the transfer tube (plus zero from the low pressure cylinder because it is at top dead center). When the transfer is finished, the exhaust gases are contained in the full volume of the low pressure cylinder plus the volume of the transfer tube. Assuming that the swept volume of the low pressure cylinder is twice the volume of the high pressure cylinder (which you probably don't want to stray too far from because of the weight balance of the pistons); If the transfer tube has the same volume as the small cylinder, then that results in a 2:3 expansion; if the transfer tube has the size of the large cylinder, then you only get a 3:4 expansion. Ideally the transfer tube would have no volume, which gives you the full expansion ratio of 1:2.

@@Pystro i agree