Shock storing conrod arm mod
 

I have been thinking for a while about a way to change an internal combustion engine to make it more fuel efficient. This mod to the conrod is the simplest/cheapest implementable solution I came up with.

I am now asking for comments why it can or can’t work. As far as I could think everything through it should work. But I probably haven't thought of everything.

The idea, as can be seen on attached "artist" :) drawing, is to put a spring on a conrod arm, and split the arm in 2 so that it is compressible. The spring can store the energy shock at peak combustion, and give it back to the crank shaft after TDC. This will increase torque and reduce fuel consumption.

It will also solve a few problems associated with internal combustion engines.
1) Reduce/eliminate NOx in diesels as peak combustion temps will be lower.
2) Eliminate detonation (ping) in petrol engines.
3) Probably have a cleaner burn with reduced wasted exhaust gasses.
4) Engine parts can be made smaller/lighter as peak combustion will be lower.
5) Have more torque as there will be more pressure on crankshaft after TDC which was stored temporarily in spring.
6) Timing can be advanced more leading to better combustion and improved fuel consumption without damaging the engine or having bad exhaust gasses.
7) Quieter engine operation with less shock and vibration and wear.
8) Less wasted heat going into cooling fluid as combustion temps are lower.

Disadvantages I can think of.
1) Conrod arm will be heavier. This can be compensated with lighter crankshaft and lighter piston.

A bit about the drawing. It is just a concept for explanation. I am sure it can be improved. I don't have all the knowledge of what type of spring strength is needed, but I am sure someone can work it out.

The conrod arm is made of 2 pieces, which fits into each other. The pieces shouldn't be able to twist in each other, as it will break the swivel point on the piston. A pin through the top conrod will slide in the slot on the side of the bottom conrod. This will stop the spring from pushing the two conrod pieces apart. At the top of the spring there is a piece of metal to hold spring so that it doesn't interfere with the swivel point at the piston.

An oil channel runs from the big end to a hole connecting it to a slot along the top conrod arm. This slot in the top conrod will always be connected to the hole opening in the bottom conrod. So as the top conrod slides into and out of the bottom conrod, there will always be a path through for the oil to the piston. The oil volume will also not change as the compression / expansion happens. This oil will also lubricate the sliding surfaces between the conrods.

If the pin in the top conrod is made better to stop the two pieces twisting in each other, the conrod arms could be made from round metal. I was just concerned about wear on the groove and pin of the top and bottom conrod arms respectively. So I drew it with square pieces fitting into each other.

Please comment on what you think the problems associated with this design is or how it can be improved, I would like to know if it can work. After that we can start messing with lawn mowers, etc. to test it.

Jan

http://ecomodder.com/forum/attachmen...3&d=1489573181

Durability and stiffness are just a few issues that I foresee. The bending forces on the conrod will require a significant overlap, adding yet more weight. The spring will also need to be huge to control the mass of the piston.

I cannot see any advantage to the design.

Simon

I think the biggest flaw in this design is, that a normal rigid conrod, doesn't cause the problems You think it does.

Hi Jakobnev
I know the conrod doesn't cause the problems, but I think it can solve the problems. The problems is caused in the combustion chamber above piston. The problem is caused by sudden combustion causing an impulse, this impulse is the sudden high pressures and temperatures. The conrod mod is to smooth the impulse and convert it into useful work.

See an example here

The resulting waveform with the modification will probably look something like the attached scan. The area of the graph above the spring pressure will be delayed and added where it is more useful to generate output work. Remember that all the pressure and heat at TDC does nothing for usefull work, it only heats combustion chamber walls and cooling fluid. The real work is only transferred to the wheels after TDC.

http://ecomodder.com/forum/attachmen...4&d=1489581041

Let me get this straight, you want to take energy going into the rod/conrod and convert it into spring/mechanical energy because you think it can be engineered in a way to delay the energy's transfer to a more opportune moment in time called peak compression?

This sounds like an attempt to mechanically augment the octane of the fuel. That is to say to control/predict the "kick". That little snap in the end of an ankle which gives some double jointed swimmers an advantage.

I do not think you will get your "kick" in this way because you can cannot destroy or create energy, you can only convert it. You are converting energy in this case from motion via fuel combustion into spring compression, there will be energy losses in the conversion (typically heat).

You want to get more mechanical energy out of the engine, heat is lost energy. You do not need more heat.

What your time might be better spent pondering is why fuel energy is spent only on the down-stroke and not the upstroke of the piston. If you ever put toe clips on your bicycle you know what I'm talking about.

https://www.youtube.com/watch?v=P1j1j0ttVPU
https://i.ytimg.com/vi/P1j1j0ttVPU/maxresdefault.jpg


There are experimental engine designs which deal with this issue, some are round, some are flat/horizontally opposed, look them up.

I'm curious why this topic is in the Aerodynamic section of the forum. Maybe you can answer that first.

In short, I think you have created more problems than you have answered, making you a better philosopher than an engineer. I'm just an architect, so take it all with a grain of salt.

EDIT: Heat caused from mechanical braking (friction/brake pads) is replaced in electric cars and hybrids with regenerative braking. This is your clue, salvage all the wasted heat in your system. Where there is heat, there is wasted energy - look at the incandescent light bulb for example.

If you had an engine which created no waste heat, it would be 100% fuel efficient.

Maybe make your engine block into a Seebeck generator?

https://en.wikipedia.org/wiki/Thermoelectric_generator
https://en.wikipedia.org/wiki/Thermoelectric_generator

I'm guessing you could eliminate your cooling system or at least go air cooled.

Hi Kach22i
Yes, check the reason why I edited the first post, to move it out of aerodynamics. It was an mistake as I posted new thread from aerodynamic thread. Didn't know it works like that.

Luckily I am a electronic engineer, not mechanical. That is why I asked comments.

If you look at a bicycle and only peddle at the same angles that an engine applies peak power, you will not get far very fast. Normally one will pedal from about 1-o-clock to 5-o-clock looking at the pedal as a watch. The engine applies most force close to 12-o-clock. If you get on your bike and stand on the pedal at 12-o-clock you will not move, you only start to move as soon as the pedal goes forward to 1-o-clock.

I fully understand heat is waste. The spring will generate very little heat. The energy it absorbs will be converted back to pressure as soon as combustion pressure goes below spring pressure. See the attached graphs I added before.

I would also fear it to actually increase the pumping losses.


Even though the heat generated would eventually be almost negligible, it's still not going to be converted back into "pressure", neither control so effectively to which direction it would be applied.

What if it were applied to the first gif below?

914World.com > Camless engines
http://www.914world.com/bbs2/uploads...93690130.2.gif

The spring would probably make it go crazy in two directions instead of one.


Well, how about some conventional layouts?


Professional Automotive Repair | Timing Belt Replacement - Professional Automotive Repair Atlanta | Marietta | Car Maintenance
http://www.atlprorepair.com/uploads/...49/1033208.gif

engine - what is difference between DOHC and SOHC? - Motor Vehicle Maintenance & Repair Stack Exchange
https://i.stack.imgur.com/HmYkM.gif

https://www.pinterest.com/pin/339810734358256743/
http://msledoux2012.weebly.com/uploa...62/6390589.gif

Camshaft VVT
http://www.formula1-dictionary.net/I...oke-Engine.gif
These Gif's are a lot closer for discussion purposes than the bicycle diagram/video. The bike one was a "what if" the up stroke was powered. Kind of a side bar distraction, trying to stay focused.

There are a lot of stresses on conrods/rods forces from all directions, just not feeling a spring application in my bones.

https://grassrootsmotorsports.com/fo...r/50017/page1/
http://i579.photobucket.com/albums/s...r/DSCF2770.jpg


https://image.slidesharecdn.com/appl...?cb=1441677730

https://www.tomeiusa.com/_2003web-ca...60_conrod.html
https://www.tomeiusa.com/_2003web-ca...07_conrod1.gif
I'm afraid to think what a one ton spring looks like.

What if you sealed the bottom part of the cylinder and had compressed air push the pistons up will fuel continued to power the downstroke??

I am trying to understand how effectively reducing the compression ratio of the combustion chamber, you are "increasing efficiency?"

In a conventional engine design, increasing static compression ratio will increase the energy gained...up to the maximum point the fuel you are using will handle..

Perhaps just do what all modern car manufacturers try to achieve..control the flamefront / swirl through the engine with head / piston design, and try to reduce the ignition / expansion of gasses event to be as close to TDC as possible (To prevent the expansion of gasses pushing the piston backwards on its upstroke).

• Improve head desgin to promote better combustion
• Improve piston design to promote better combustion
• Reduce time before TDC
• reduce friction in the combustion chamber (Short skirts, lighter weight)
• Use higher quality materials that do not transfer heat (Ceramics etc)
• use higher quality fuel that allows quicker, more controlled flamefronts

Of course, a standard internal combustion engine (4 stroke especially) is pretty poorly designed interms of efficiency..
Maybe look at the Miller Cycle / Wankel / etc engine designs..many are much more efficient than a typical 4 stroke..of course they have a few other faults that need to be taken into account..(Reliability / emissions / size / weight / serviceability etc)

why not just retard the timing?

I had a similar idea to yours, well the result is similar but the means are totally different.


I was thinking of using ion sensing ( senses cylinder pressure, Harlan has a few posts on it) and use controlled heated air to speed up the reaction in lean burn (so uncombusted fuel does not escape, burning the valves) and use water injection to slow down combustion so that the power does not spike but is smoother during the stroke. Also adjusting the timing....

Hi Kach22i
Thanks for all the diagrams. I like the camless engine, nice and simple. The flywheel momentum will make it continue in the same direction. The one advantage of the spring is to stop the conrod from breaking. I also don't know what size spring will be needed, but that's why I'm asking.

If you get into the maths behind it, you will find that is the impulse of the combustion that breaks the conrod. That is why people die in accidents and when they fall from the sky. It is not the fall that kills, but the sudden stop.

Craysus:
I am trying to understand how effectively reducing the compression ratio of the combustion chamber, you are "increasing efficiency?"

The idea of the spring is to keep the conrod length standard except on the power stroke. It will only compress if pressure rises above a set point. Then expand later in the power stroke and put back most of that energy on the crankshaft. So its use is to flatten the peak power and make it more useful. The compression ratio will stay the same as the spring will do nothing during compression, only after fuel starts burning and build up enough pressure will the spring compress.

Stovie:
What if you sealed the bottom part of the cylinder and had compressed air push the pistons up will fuel continued to power the downstroke??

Haven't thought about it, could use exhaust gas to push op the piston. But would you get a gain in efficiency.

Mobilone:
why not just retard the timing?

I tried it. On my diesel it just makes white smoke.(un burnt diesel due to low combustion temperatures.) And fuel consumption is bad at high speeds.
I finally sorted out my diesel pump internal pressure and dynamic timing 3 days ago. It's a different pickup now. Will see consumption this weekend.
What we actually need is detonation at about 45-60 degrees ATDC. But at that stage the air temps and pressure is too low for detonation.

So the plan with this mod is to advance the timing to get detonation or very fast and complete combustion close to TDC and then store the energy for use ATDC.
Jan

Your idea seems to do exactly the opposite of what an Atkinson cycle engine does:
https://www.youtube.com/watch?v=gmwpljA8sqQ

Energy, all energy be it electricity, mechanical spring, chemical and so forth shall follow the path of least resistance.

You are attempting to press your spring against nothing, the air in the cylinder will not push the spring more than the camshaft connected to the transmission, connected to the wheels (the path to applying power to the road).

I think your explanation of delaying or flattening out the peak power as a safety feature for breaking conrods was not your original goal, but a nice try at a save on your part.

Going back to the alternate designs I've brought up and posted, in general they typically have flaws greater than current ICE (Internal Combustion Engine) technology. Complexity, costs, the ever present laws of thermal dynamics, serviceability, limits on materials, and so forth.

I'm not a huge fan of ICE, on paper they seem to be the least likely technology to have success, and yet here we are 100 years later living with them often as our only choice.

Food for thought:

Work by Variable Force, and Spring Force
http://spiff.rit.edu/classes/phys311.../spring_7.jpeg
How do springs work? | How do springs store energy?
Spring (device)
https://en.wikipedia.org/wiki/Spring_(device)
Springs are a Steam-Punk technology, they have been replaced in thermostats, automotive suspensions and many other uses for good reason. I would avoid adding more of them to any modern design, more than you have to anyway (dead weight).

I did not read all responses, sorry. I think the most interesting part of this is, could this store some of the combustion energy and release it when it will do the most good, i.e. when the conrod is at or very near to 90deg to the crank.

The two biggest drawbacks would be: can a conrod be designed like this and still be reliable, also, will a spring wear out too fast to be feasible. Perhaps an air "spring".

Yes, heat will be generated bit perhaps it can outweigh those losses by providing more force to the crank when the multiplying effect is the largest (angle).

Thank you. I can see you understand the concept. :thumbup: Yes, that is exactly the idea to release the energy later, maybe not at 90 degrees, but closer to it.

The air spring is an excellent idea, will have to put some thought into it.
Jan

Hi Cach22i

If combustion pressure gets very high, the pressure will not break the conrod trying to turn the engine much faster than it currently is turning. The very high combustion peak pressure will push down on the piston, and the crankshaft will resist it as the engine can't accelerate as fast, so the spring will compress. The spring is not pressing against nothing. Maybe my drawing is a bit unclear.

Go check point 4 in the first post. It wasn't a nice try at a save.

Thanks for all the external links to springs. I confirms what I thought about springs that they don't loose much energy. Also the harmonic oscillations of the spring will be perfect for what is needed.

Your vehicle suspension is some sort of spring system with dampers(shocks) to absorb the harmonic oscillations. I will definitely be keeping mine even if it is stone age technology.

To everyone else:
I am not very interested in different technology engines. Please comment on why this concept won't work or why it could and what can improve. If there is something similar or very relevant please let us know.

How about a "magnet" spring??

https://m.youtube.com/watch?v=BHYSsqHsnDE

I think that would allow some simplicity in the design!?!

Ideally, assuming this idea can work, i think anticipating the spring compression and then increasing the compression ratio back up to what is common on todays engines could mean big power numbers. You would effectively be getting a longer stroke out of any given engine.

Another effect, as the piston is decelerating toward bdc on the intake stroke, it may also compress the spring at higher engine speeds allowing for a larger effective displacement than static.
...maybe not since the spring would definitely be compressed on tdc.

Has OP (or anyone else, for that matter) found a way to overcome the tendency of all of the sprung weight of this piston/spring conrod contraption to resist the continual changes in velocity due to moving up and down within its cylinder?

That continually varying momentum of the sprung mass, interacting with the elastic nature of the spring itself, is going to set up for some rather undesirable engine speed-dependent harmonic motion.

The compression ratio shouldn't change. The spring should be stiff enough to only start compressing after fuel burning has well progressed. I don't see the need to increase power in today's engines, only reduce wasted heat(increase efficiency) to get more energy to the wheels and less to the exhaust and radiator.

From what I have learned about engines you need a certain compression to get the air/ air fuel mixture hot enough. After that it will ignite(by itself or sparkplug) and burn by itself. After igniting it releases heat which raises temps and pressure more. At a certain point the combustion will be hot enough so there is no combustion gain raising the temps more.

The high temps get absorbed by the cylinder walls, head and piston. Which is waste heat to radiator eventually. If the peak pressure and thus temps is lower, the difference between engine temp and combustion temps mean less heat will get absorbed by engine.

Also T Vago:
The spring should be stiff enough not to compress at BDC, only closer to combustion peaks. If it does compress at BDC I think the engine will have problems during combustion to burn the fuel. Someone who knows how to work these things out will have to enlighten us.

I've always had a issues with spring problems in physics classes and those friction-less ladder problems too.

Guess you can tag me out on this topic.:o

So at a 30:1 compression ratio (assuming temperature of the compressed gas stays at 60f which ot won't), the spring will need to be able to resist (425 psi x (piston area)in2) roughly 4500lbs depending on piston size and the effective dynamic compression ratio.

Is that math right? Seems high.

If that is accurate, you're certainly not using a mechanical spring.


I re-ran some numbers using 17.3:1 compression of a cummins 6.7 and 15 psig of boost, roughly 2700 lbs of force.

Even though your intention doesn't sound bad, it's neither simple or practical at all.

Thanks, this is what I was looking for. Some math that says it's possible or not. I can't say if it is correct or not as I don't know how to calculate it.

What bothers me is that a small starter motor is able to turn the engine against the compression and start it. Maybe it's the gearing that makes it possible.

Maybe there is someone that can point us to the correct formulas, etc. to calculate it.
Thanks

If the resistance due to compression was anywhere near the force of expansion, the engine wouldn't turn at all.

That's a really high compression ratio and those are large cylinders.

Still a ton = 2,000 lbs and that's what I posted earlier, over a ton of force.

Your math matches.

Next great idea.................?

Seems like excess complexity to me, especially for a critical component that has many harsh demands placed upon it.

Consider how such a part would wear too.

I've read about spring-loaded detonation dampers located in the cylinder head which would be orders of magnitude simpler.

Magnets:they really do not like heat...

That amount of force, your springs are roughly the size of the springs in your suspension.

Also, when you fondle a spring, it goes wobbly wobbly, that could be deteimental in an engine that has variable rpms. You should look at tuning mass spring damper systems (if you have friends that are good in electronics, it is the same as RLC {capacitance, inductance and resistance} circuits).

Also at those speeds and forces I doubt that your spring will be linear (which may or may not be to your advantage).

Hello DieselJan,

Huh, this is interesting. I did some rough calcs using a Chevy Duramax Diesel engine at 4,000RPM (a bit higher than recommended, but it can get there) because I could find the relevant numbers. 4.06" bore by 3.9" stroke, 850 gram piston. After converting everything to SI units, I got a peak acceleration force on the piston of about 5kN when it is slowing down from max speed at half-stroke to 0 speed at BDC. With a peak combustion pressure of ~2500PSI, the force exerted on the piston is ~143kN, or about 30x that of the accelerating piston. At least that means that if you have the right spring for peak cylinder pressure it won't move much due to piston acceleration forces.

Trouble is, that high a force will require a spring that won't fit the available space. Converted back to US units, that's a bit over 16 tons of force at peak cylinder pressure. Think needing ~4 main suspension springs from a fully-loaded tractor-trailer rig (80 tons).

You could use a gas spring, but to do that you'll essentially end up with two pistons within the same cylinder, one a "free" piston in contact with the combustion gases, and the other trapping some 2500psi+ gas between it and the combustion piston, with some means to keep them from getting further apart than the height needed for proper compression ratio. Unfortunately, that doubles your piston ring friction and you have to figure out how to keep that gas pressure topped up. Packing the gas spring into the con-rod/piston package would mean higher pressures and more elaborate sealing methods, which may add less friction than a second set of piston rings, but it still is quite an addition.

I don't think you'll get sufficient efficiency gains to offset the additional parasitic loads from the added friction, rotating mass, etc. that your re-design adds. Sorry.

I know you didn't really want a different way to get the same effect - just a critique of your idea - but there are some other things out there that may interest you, so go ahead and ignore the rest of this if you want.

A simpler way of getting more leverage at peak cylinder pressure/TDC is offsetting the piston bore relative to the crankshaft, or offsetting the wrist pin in the piston. Basically, when the piston is at TDC, the crankshaft is rotated a bit beyond the point where the crank arm would be vertical. When peak cylinder pressure occurs, it will be working on a lever arm right away, rather than pushing straight down the vertical stack of piston/wrist pin/conrod/crank bearing/main bearing/main bearing cap, and trying to squeeze the oil films between those parts.

You can also play with combustion pressure profiles by changing how the mixture reacts. There's some really neat work being done out there.

You mention that you are an electronic engineer - check into "Reactivity Controlled Compression Ignition" or similar (U of Wisconsin has some good stuff here: RCCI (Reactivity Controlled Compression Ignition) Engine - Wisconsin Engine Research Consultants - Engine Research Center) where they use multiple injections of fuel of varying or modified octane/cetane rating to control the reactive species mix in the combustion chamber, with a lot of control over peak temperature, peak pressure, etc. They have achieved brake mean thermal efficiency up to 57% with cetane enhancer modified gasoline (example of their work here: High Efficiency, Low Emissions RCCI Combustion by Use of a Fuel Additive). They have an early version ("only" about 47%-52% brake mean thermal efficiency depending on fuels used) that has both port (octane-rated fuel, or "low reactivity") and direct (cetane-rated fuel, or "high reactivity") injection compression ignition in a high-compression engine. This may be in your area of expertise - figure out how to graft the port fuel injection system from a flex-fuel spark ignition engine onto a modern common-rail direct injection diesel engine, and get the two ECU's to talk to each other or be controlled by a third computer, in order to get the RCCI results. If you can come up with the way to get that sort of thing to work, you could open up some really interesting aftermarket modifications that don't require heavy engine wrenching - just appropriate junkyard scrounging and code work, plus an auxiliary fuel system.

Interesting, I could not find it, but I found the below. Uses air/gas and oil for "shock abortion" (spring-like) and increasing chamber size (more power).

Detonation control device for an internal combustion engine
https://www.google.ch/patents/US5063883
https://patentimages.storage.googlea...S5063883-1.png

Nowadays that direct-injection is going mainstream, some mechanical provision to overcome detonation seems more likely to become redundant anyway.

Four pages in two days?

Here's a one word answer : Hysteresis.

I think the picture of the con rod bent in half says it all. Are we talking about an I-beam or H-beam con rod.

What is to be gained over offsetting the wrist pin in the piston??

The only thing I can see surviving in that environment would be a sintered-metal 3D printed nano-scale structured beam that is rigid in X and Y but compressible in Z (for certain values of X,Y and Z).

Hi Everyone involved
Thanks for helping me understand the limits and problems of this design, especially Cajunfj40. I never knew there was such high forces on the piston, wow. The problem was that I didn't know where to start to calculate these things, so I decided to just ask. Thanks for all the comments and suggestions.

I am into electronics and still think that the internal combustion engine's biggest gains will be mechanical or in the way the fuels is used. In my opinion electronics is there for "fine tuning" or making it possible. There is constantly gains made due to things being changed around the engine, but I still think a change in the operation of the engine will have a jump in gains.

Let me quickly explain the reason I said I am not interested in other technologies. I am actually open to any suggestions.
I have been reading on Ecomodder for about 4 years. Looking for modifications I can do to improve FE. It could have taken me 2 years if a lot of threads weren't "Hijacked/off topic". Take the Centurion build thread which is excellent and full of useful information, currently 63 pages. It could have been much shorter and condensed if it weren't for some people who want to add their one idea the whole time.

Just an suggestion. If you are very concerned with a certain topic, start a thread about it which can be discussed in detail. Then just comment in other people's threads with a link. This will benefit everyone reading ecomodder in future. So let's keep one topic/ one related topic per thread.

As you can see I have just hijacked my own thread.:D
Thanks
Jan

Mmm, topic drift.
 

Hello again DieselJan

Not a problem - I like to share.

Well, writing from the perspective of a mechanical engineer that's been studying efficiency gain concepts for over 25 years as a hobby, and who also favors mechanical changes because I understand them better than the other areas, the standard reciprocating piston engine design actually doesn't have much left in it for gains, IMHO. At least, this appears to be true for the two areas you focused on - spreading out peak combustion pressure load so that more of it can get to the crank in both normal and abnormal (knock/ping) operating regimes. kach22i found that fascinating pneumatic/hydraulic controlled mechanical "detonation relief" dynamic compression release device for the abnormal conditons, but that's an extremely complex way of solving a simple problem. The thing is, those conditions are abnormal for a reason. By changing things like intake mixture tumble and swirl, squish geometry, mixture profile in the cylinder, etc. the abnormal regime can be avoided entirely - and generally there are efficiency gains in doing those things as well. For general thermal efficiency, most of the mechanical gains are in lightening the rotating assembly, reducing the overall mass for faster warmup, lower viscosity oils to reduce drag, better finishing/tolerances to reduce friction, better tuning of intake/exhaust for the dominant operating RPM's, etc.

In terms of how the fuels are used, you are back to electronics, at least if you want a responsive engine that runs well/clean at several different operating regimes. Today's fast computation and multiple sensors allow real-time control of mixture, timing, cam phasing, valve timing, dynamic compression ratio, all sorts of things to keep the combustion process operating as efficiently/cleanly as possible.

In another context, I moderate a weekly in-person informal discussion group. I also, as part of my job, run a technical update meeting. It takes a lot of work to keep a discussion focused on a single topic/agenda. I think this site does rather well wrangling a disparate group of enthusiasts with widely varying interests/knowledge bases/communication skills, etc. :thumbup: Sure, there are lots of digressions in threads. Topic drift is basically inevitable under those conditions if you don't have someone riding herd on a given thread. That and sometimes really interesting things come out of the topic drift, sometimes spawning new threads.

It's also free, as in you are not required to pay anything to be able to contribute to/gain from the site.

This is a decent suggestion overall, and might be worth working into a general "rule of conduct" for a FAQ/sticky on how to comment here, preferably with some general guidelines like when to start a new thread, how to split off into a new thread and/or how to request that the mods do a move/split. Unfortunately, it comes across a bit like CATFOTFIC when phrased like this as part of a general complaint about how the site is run/presented. :( I see the mods already splitting threads, moving them to different areas, etc. Making them the topic police in every thread is asking a bit much, IMHO. Maybe you could start a thread in Forum News & Feedback on creating a "how to comment" sticky? Possibly I've missed an existing FAQ - there may already be a general comment guidelines sticky beyond the sub-forum guidelines.

See? Topic drift is inevitable. Even when you have total control over your own post. :D

Keep thinking up ideas, read widely in the available literature, and keep contributing - I found your post interesting. :thumbup: Even ideas that aren't practical generate lots of related thoughts/ideas. Threads that have an unworkable idea to start with can generate lots of avenues of exploration as folks chime in with other ideas, however tangentially related.

(and yes, I did add some emoji here, even though I generally avoid the things because I am not that swift at picking up how they are supposed to be used. :rolleyes:)

Thanks,
-cajunfj40

Topic drift is your friend. 'Nuff said.

Internal combustion was 'settled science' by the end of WWII and was thoroughly regression tested on the drag strips of Southern California. You can go faster by drilling holes in the tops of the pistons. Who knew?

That's two things, right? Electronics is the window to plasma physics.

In terms of posting; I've seen some threads managed by the OP updating the first post to TLDR the whole thread. Another thing is the wiki: Main Page - EcoModder

Perhaps simplify your thought a fraction..

Adjust the cylinder head combustion chamber profile based on the timing requirements..have a lower compression at TDC, and increase the compression a few degrees after TDC...this would effectively perform the same function as your sprung piston?

CSRV vs. Poppet Valve - Coates International Ltd.

Using a cammed intake system similar to above, and taking changing the profile based on simple rotation. You could imagine taking this to the next phase, and implementing a Wankel style interface as the cam, instead of the twin cams used byu coates...and therefore simplifying the movement down even further..

Alternatively, electrically controlled "valves" could be utilised on a more conventional head...and if the valves opened / shut normally, but could be extended INTO the cylinder, to increase compression at the desired part of each scycle..(Making the valves a solid tube to take up volume..maybe twisting open / closed to vary between a solid tube and a fuel delivery / exit path)

Just some random thoughts to help with overcoming the requirement for 4 x truck springs being inside a 4" cylinder bore.. (Havent invented a Tardus as yet...sorry..)...

Is that the go-faster trick of drilling down behind the compression ring so combustion pressure increases the sealing force on the power stroke? Allows you to run lower ring tension for reduced friction on the rest of the strokes at the cost of a bit more oil consumption. A nice example of using gas pressure instead of mechanical spring force. Could potentially work in a "burn and coast" optimized vehicle that spends almost no time off peak bsfc.

Historically, that approach does not tend to do well on the street. The small gas ports tend to clog easily, and then you end up with an oil burning bucket of crap. There is a lot of conjecture on which type of port (horizontal or vertical) is more suitable for street cars. Also, the benefits are more from better ring control than lower friction, and more so with much higher RPMs and power outputs than we are talking about here.

Simon