I am currently modifying my Honda Gx390 engine to run off of hydrogen. I will have to redesign the top of the engine to allow fuel injectors. One of the drawbacks to hydrogen is since it is so tiny it can fit through cracks really easily. Therefore I wanted to make the piston hold 5 rings. However, since the stock piston only allows 4 rings I would need to replace it. The problem with this is that I remember reading somewhere that crankshafts are calibrated to their piston's weight, so by replacing it I am afraid I will put unnecessary stresses on the engine. The Gx390 does come with a counterbalance in the main body so I don't know if it's the same. Any help is much appreciated. Thank you
Piston and crankshaft
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Hi. I would state that hydrogen instead of gasoline is of no concern in the cylinder. Hydrogen at high pressure is a pain to keep without leakage, migrates even through solid stainless steel, but this is not the state in the cylinder. There you will have, in practice, the same conditions as with normal fuels. Everything upstream the injector will however be a challenge.
Thank you for your responce. That saves alot of time and money lol thank you.
Changing the weight of the piston will change the balance characteristics.
The primary imbalances (from the piston moving up and down) are generally handled by the crankshaft counterweight. These are most noticeable as up and down shake at 12:00 and 6:00 in a single cylinder vertical engine.
The counterbalance shaft and its eccentric weight is to help cancel the secondary imbalances that come from the crankshaft counterweight and conn rod big end swinging around and are most noticeable as rocking around the crankshaft centerline at 9:00 and 3:00.
The primary imbalances (from the piston moving up and down) are generally handled by the crankshaft counterweight. These are most noticeable as up and down shake at 12:00 and 6:00 in a single cylinder vertical engine.
The counterbalance shaft and its eccentric weight is to help cancel the secondary imbalances that come from the crankshaft counterweight and conn rod big end swinging around and are most noticeable as rocking around the crankshaft centerline at 9:00 and 3:00.
Never seen an engine with 4 rings(at least, not in the last 50 years or so) ....I think you'd better look again.
Unless you count the two part oil ring as 2 rings, but not a normal practice.
Overall, the idea is hardly worth the effort, especially on an old bushbasher stationary engine given the (so far) problems you haven't thought about.
Hi, Simply "don't do it".... because:
The set of piston rings are not a perfect seal, and adding rings is virtually no benefit anyway.
The top 2 rings in conventional engines are "compression rings" - deemed adequate to prevent enough leakage so you develop the compression to start the engine at the lowest crank speed. They also reduce BLOW-BY gases (from the high pressure during combustion) to acceptable levels. The bottom ring is an OIL CONTROL RING: This keeps out almost all the oil from getting from below the piston to the combustion chamber, where excess oil would drain the engine too quickly, and also polute the exhaust stream - which in car engines has acatalyst that gets fouled with and metal molecules from the additives in the oil. )Hence the limited life on many cars of over 80,000 miles before you need to fit a new one)
When the engine is running, the compression can be achieved with one or no compression rings, but Blow-by is increased, which is a loss of power and efficiency from the engine. Considering that at the end of the compression rings there is a gap maybe 0.001" to 0.003" wide (to compensate for differential expansion of the cylinder and piston at varying temperature during warm-up etc.) trying to prevent hydrogen molecules from escaping the combustion chamber is a waste of time and effort.
I hope this helps your understanding?
It is actually quite complex engineering - best left to Mr Honda et al, as I know they have expert engineers whose whole task is Piston ring sealing, etc.
Good luck with the H2 conversion,. I shall be pleased to hear more.
K2
The set of piston rings are not a perfect seal, and adding rings is virtually no benefit anyway.
The top 2 rings in conventional engines are "compression rings" - deemed adequate to prevent enough leakage so you develop the compression to start the engine at the lowest crank speed. They also reduce BLOW-BY gases (from the high pressure during combustion) to acceptable levels. The bottom ring is an OIL CONTROL RING: This keeps out almost all the oil from getting from below the piston to the combustion chamber, where excess oil would drain the engine too quickly, and also polute the exhaust stream - which in car engines has acatalyst that gets fouled with and metal molecules from the additives in the oil. )Hence the limited life on many cars of over 80,000 miles before you need to fit a new one)
When the engine is running, the compression can be achieved with one or no compression rings, but Blow-by is increased, which is a loss of power and efficiency from the engine. Considering that at the end of the compression rings there is a gap maybe 0.001" to 0.003" wide (to compensate for differential expansion of the cylinder and piston at varying temperature during warm-up etc.) trying to prevent hydrogen molecules from escaping the combustion chamber is a waste of time and effort.
I hope this helps your understanding?
It is actually quite complex engineering - best left to Mr Honda et al, as I know they have expert engineers whose whole task is Piston ring sealing, etc.
Good luck with the H2 conversion,. I shall be pleased to hear more.
K2
Bentwings
Well-Known Member
I too don’t think the hydrogen will be a problem . I’d also skip the 4?ring piston for the same reason given if you really want to complicate things you could make provision forevs **** ring but just making the ring would be a challenge . We have used these on race cars for years . They are stainless with coating and require fine cyl finish. But some of the conditions we have used them go against all the rules.
We have even run nitro engines with broken rings as there weren’t any good ones in the spare parts box . I wouldn’t worry about crank balance unless you radically change piston weight even then unless you have precision balancing equipment there is little you could do .
Keep the same piston, look into ( Total seal rings ) All of the race cars i ran, never lost more than 2% on leak down and that's with valves to consider. Keep in mind, the break in can be brutal in low power engines. Worth it!
The concept is easy. The machining may be different, due to the size
The concept is easy. The machining may be different, due to the size
A typical IC engine can be modified to operate on gasoline, kerosene (think John Deere old-school tractors), propane, natural gas, and basically any liquid or vaporized fuel that will burn relatively cleanly and provide the required power (without excessive knocking/pre-detonation).
Just as there is just minor changes on many small generators to burn natural gas, propane, or gasoline (some are triple-fuel configured), I would think only minor (if any) changes would need to be made to an engine mechanically just because you are burning hydrogen instead of propane or something similar.
I don't think there is anything particularly volatile about combusting hydrogen in the cylinder as compared to combusting propane.
The pressures should be about the same.
What would need to be different is the fuel system for hydrogen.
Propane systems use some sort of diaphram on-demand system, and with hydrogen being a gas, I would guess also a diaphram on-demand system would be used.
The leakage under high pressure with hydrogen would seem to make it difficult to store in a pressurized tank and/or delivery system.
I would think the leakage for a low pressure hydrogen fuel system would be minimal when the engine is operating.
When the engine is stopped, the hydrogen flow in the low pressure system would stop.
Probably the worry would be when the engine is not running, and trying to keep the high pressure fuel tank from seeping out into your garage.
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Carbon wrapped with Kevlar, sealed with epoxy... Maybe?
It works in space....
If you look at how a CIS injection system works, maybe?
It works in space....
If you look at how a CIS injection system works, maybe?
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There are many different designs of Gas tank for hydrogen. This fuel is managed by the Car companies who are experimenting with it as a fuel, and I have seen the Carbon fibre tanks they need to use - Very heavy for not a lot of real energy capacity.
https://www.aliexpress.com/item/100...c5bd71e4ef3b049c20016da20d8&afSmartRedirect=y
But when I needed to install a Hydrogen gas feed system into a Laboratory, I learned some of the issues of Hydrogen.
The molecules of Hydrogen are small - so small that "Normal" materials that hold fuels and gases do not always contain Hydrogen. In fact the helium molecules (about 4 times bigger than Hydrogen) are used 100% as the leak test gas for fuel tanks for petrol etc. Hydrogen can (and will) permeate through most membranes of rubber, plastic, some metal welds, etc. - hence the heavy and expensive careful manufacture of tanks for hydrogen. ANY welded steel tank - or pipework, fittings, etc. - must be professionally made by someone certified appropriately for making the welds for Hydrogen equipment.
We had to use a special certified and trained contractor to do the lab pipework for Hydrogen, because that was the law. They are rare and expensive experts.
Some stuff I have not read, but may enlarge upon what you can do with Hydrogen.
https://cms.law/en/int/expert-guides/cms-expert-guide-to-hydrogen/united-kingdom
ASME B31.12
The problem with Hydrogen.
It simply explodes!
In a combustion engine, explosions cause very high peak pressures (shock waves), so necessarily things have to be heavier and stronger than with a "regular" fuel that burns with a flame front. - Thus increasing pressure over the time it takes to transmit the initial point of combustion (the spark, etc.) to the far corners of the combustion chamber. This is a short time, and rapid combustion, but not the peak pressure achieved when hydrogen and air mix. - This has taken car makers decades to work-out and overcome, and yet there are still no real signs of Hydrogen becoming road fuel... just vague forecasts. - I know guys who worked on the Hydrogen fuelled cars for about 20 years, and reckon they have a job for life!
Another problem with Hydrogen - In air, with any source of ignition, it simply explodes! And because the molecules of Hydrogen are so small, almost any joint (even where 2 welds meet on a steel tank) can leak, and the ensuing gas cloud is a bomb waiting to go off..
BUT with seamless stainless steel tubing, compression fittings, certified welded (steel) pressure vessels, or other proprietary vessels for hydrogen, it can be made to be safe (-ish?). Or so they though about the Hindenburg...?
SO please take care... Hydrogen really is "rocket science fuel"... Don't take my word for it, read about it in "Professional papers" on the Web. There is plenty to read!
https://www.eprg.net/fileadmin/EPRG_Dokumente/FR-221_2020_Literature_study_hydrogen.pdf
K2
https://www.aliexpress.com/item/100...c5bd71e4ef3b049c20016da20d8&afSmartRedirect=y
But when I needed to install a Hydrogen gas feed system into a Laboratory, I learned some of the issues of Hydrogen.
The molecules of Hydrogen are small - so small that "Normal" materials that hold fuels and gases do not always contain Hydrogen. In fact the helium molecules (about 4 times bigger than Hydrogen) are used 100% as the leak test gas for fuel tanks for petrol etc. Hydrogen can (and will) permeate through most membranes of rubber, plastic, some metal welds, etc. - hence the heavy and expensive careful manufacture of tanks for hydrogen. ANY welded steel tank - or pipework, fittings, etc. - must be professionally made by someone certified appropriately for making the welds for Hydrogen equipment.
We had to use a special certified and trained contractor to do the lab pipework for Hydrogen, because that was the law. They are rare and expensive experts.
Some stuff I have not read, but may enlarge upon what you can do with Hydrogen.
https://cms.law/en/int/expert-guides/cms-expert-guide-to-hydrogen/united-kingdom
ASME B31.12
The problem with Hydrogen.
It simply explodes!
In a combustion engine, explosions cause very high peak pressures (shock waves), so necessarily things have to be heavier and stronger than with a "regular" fuel that burns with a flame front. - Thus increasing pressure over the time it takes to transmit the initial point of combustion (the spark, etc.) to the far corners of the combustion chamber. This is a short time, and rapid combustion, but not the peak pressure achieved when hydrogen and air mix. - This has taken car makers decades to work-out and overcome, and yet there are still no real signs of Hydrogen becoming road fuel... just vague forecasts. - I know guys who worked on the Hydrogen fuelled cars for about 20 years, and reckon they have a job for life!
Another problem with Hydrogen - In air, with any source of ignition, it simply explodes! And because the molecules of Hydrogen are so small, almost any joint (even where 2 welds meet on a steel tank) can leak, and the ensuing gas cloud is a bomb waiting to go off..
BUT with seamless stainless steel tubing, compression fittings, certified welded (steel) pressure vessels, or other proprietary vessels for hydrogen, it can be made to be safe (-ish?). Or so they though about the Hindenburg...?
SO please take care... Hydrogen really is "rocket science fuel"... Don't take my word for it, read about it in "Professional papers" on the Web. There is plenty to read!
https://www.eprg.net/fileadmin/EPRG_Dokumente/FR-221_2020_Literature_study_hydrogen.pdf
K2
Machbuild. I have just read your initial query.
I assume you already are aware of the problems of hydrogen storage and piping to the final valve, where it enters the engine. I only ask that you try and comply with all the regulation stuff to give yourself a fighting chance of not blowing yourself and any passengers of your Honda to the next life...
But regarding the balance of the engine, and extra rings, I understand the car industry is working to manage the hydrogen potential leakage (pre-combustion blow-by) by the venting system from a "perfectly sealed crankcase, etc.". - I.E. take all those gases (pre-combustion and post combustion blow-by) and passing them back through the engine with the intake air. This should ensure no free hydrogen escapes from the engine itself. BUT the "factory built Honda engine" you have will NOT be capable of being completely gas tight, just enough to cope with the regular blow-by gases.
Adding or reducing any weight to piston assemblies will throw the balance away from Mr. Honda's reliable build. The pistons, rings, piston pins, and circlips are weighed, coded and then selected codes are fitted to selected coded con-rods, according to the codes on the crankshaft, from when that was dynamically balanced and measured, as was the flywheel and all the rotating parts of the balance shaft system, so the engine is as perfectly balanced as Mr Honda planned.
The piston assemblies (part of my responsibility when I was in Engine design at a car maker), are balanced to a few micrograms, which is less than the consistency with which parts can be made, therefore requiring the manufactured assemblies to be split into 5 "codes" - simply a variation of only 20% of the variation of manufactured parts. - A single small speck of swarf can change the weight from 1 code to the next.
So don't change the pistons, etc.
I ask the simple analogy: Would you take a finely made precision Swiss watch and insert a part you made with a file in your workshop? (perhaps you are that good, but most of us are not.). My grandfather used to repair broken clocks, but only ever used proprietary replacement parts in expensive watches. The required accuracy was beyond the capability of all the "Home workshop" stuff you can buy. Please treat your Honda Engine like a precision watch. The guys in the factories did....
Good luck with your Hydrogen conversion!
K2
I assume you already are aware of the problems of hydrogen storage and piping to the final valve, where it enters the engine. I only ask that you try and comply with all the regulation stuff to give yourself a fighting chance of not blowing yourself and any passengers of your Honda to the next life...
But regarding the balance of the engine, and extra rings, I understand the car industry is working to manage the hydrogen potential leakage (pre-combustion blow-by) by the venting system from a "perfectly sealed crankcase, etc.". - I.E. take all those gases (pre-combustion and post combustion blow-by) and passing them back through the engine with the intake air. This should ensure no free hydrogen escapes from the engine itself. BUT the "factory built Honda engine" you have will NOT be capable of being completely gas tight, just enough to cope with the regular blow-by gases.
Adding or reducing any weight to piston assemblies will throw the balance away from Mr. Honda's reliable build. The pistons, rings, piston pins, and circlips are weighed, coded and then selected codes are fitted to selected coded con-rods, according to the codes on the crankshaft, from when that was dynamically balanced and measured, as was the flywheel and all the rotating parts of the balance shaft system, so the engine is as perfectly balanced as Mr Honda planned.
The piston assemblies (part of my responsibility when I was in Engine design at a car maker), are balanced to a few micrograms, which is less than the consistency with which parts can be made, therefore requiring the manufactured assemblies to be split into 5 "codes" - simply a variation of only 20% of the variation of manufactured parts. - A single small speck of swarf can change the weight from 1 code to the next.
So don't change the pistons, etc.
I ask the simple analogy: Would you take a finely made precision Swiss watch and insert a part you made with a file in your workshop? (perhaps you are that good, but most of us are not.). My grandfather used to repair broken clocks, but only ever used proprietary replacement parts in expensive watches. The required accuracy was beyond the capability of all the "Home workshop" stuff you can buy. Please treat your Honda Engine like a precision watch. The guys in the factories did....
Good luck with your Hydrogen conversion!
K2
They converted a number of mail delivery trucks at the post office near my house to hydrogen.
They looked like a regular mail truck.
Not sure what they did if anything to the stock engine other than fuel delivery modifications.
I recall the hydrogen storage tank was spherical, about six feet in diameter, and well away from the main building.
As I recall, all the hydrogen-powered trucks parked outdoors in front of the building, so no significant problems from leakage (I assume).
I would guess that the leakage is a very slow thing; probaby more like seepage.
You would not want any seepage inside of a building, but outside, I don't think a little seepage would be too dangerous (not positive though).
Like at a gas station, people often spill gasoline all over the place, and it is not really a problem since the air/wind evaporates it relatively quickly.
In the old days, it was very common for people to pull into a gas station while smoking a cigarette, and even fill their car while holding a lit cigarette. I worked in a gas station when I was young, and some of the employees worked all day while smoking.
I started to read the link, but stopped reading when I saw the line "UK government published its Ten Point Plan for a Green Industrial Revolution".
Not to get all politicized and such, but lines like that to me mean "It has nothing to do with science; it is all politically driven".
As useful as trying to stop cows from farting.
Sorry for the rant.
Edit:
I did some design work for a cooking oil company one time, and they use hydrogen to hydrogenate the oil.
They injected hydrogen into heated cooking oil, in the prescence of a catalyst (perhaps platinum).
That hydrogen piping as I recall was just steel pipe, and it was run all over the plant.
So I assume that with a little ventilation, there is no problem with seepage of hydrogen from the piping sytem.
In wastewater plants, the classification of a hazardous area is determined often by the ventilation (air changes per hour), and with enough ventilation, you can drop to a less hazardous classification, or sometimes drop even to a non-hazardous location.
Methane is what gets generated at wastewater plants that is combustible.
.
They looked like a regular mail truck.
Not sure what they did if anything to the stock engine other than fuel delivery modifications.
I recall the hydrogen storage tank was spherical, about six feet in diameter, and well away from the main building.
As I recall, all the hydrogen-powered trucks parked outdoors in front of the building, so no significant problems from leakage (I assume).
I would guess that the leakage is a very slow thing; probaby more like seepage.
You would not want any seepage inside of a building, but outside, I don't think a little seepage would be too dangerous (not positive though).
Like at a gas station, people often spill gasoline all over the place, and it is not really a problem since the air/wind evaporates it relatively quickly.
In the old days, it was very common for people to pull into a gas station while smoking a cigarette, and even fill their car while holding a lit cigarette. I worked in a gas station when I was young, and some of the employees worked all day while smoking.
I started to read the link, but stopped reading when I saw the line "UK government published its Ten Point Plan for a Green Industrial Revolution".
Not to get all politicized and such, but lines like that to me mean "It has nothing to do with science; it is all politically driven".
As useful as trying to stop cows from farting.
Sorry for the rant.
Edit:
I did some design work for a cooking oil company one time, and they use hydrogen to hydrogenate the oil.
They injected hydrogen into heated cooking oil, in the prescence of a catalyst (perhaps platinum).
That hydrogen piping as I recall was just steel pipe, and it was run all over the plant.
So I assume that with a little ventilation, there is no problem with seepage of hydrogen from the piping sytem.
In wastewater plants, the classification of a hazardous area is determined often by the ventilation (air changes per hour), and with enough ventilation, you can drop to a less hazardous classification, or sometimes drop even to a non-hazardous location.
Methane is what gets generated at wastewater plants that is combustible.
.
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Machbuild,
I am sure you will have read many documents such as this,
https://www1.eere.energy.gov/hydrogenandfuelcells/tech_validation/pdfs/fcm03r0.pdf
But this one explains the point about crankcase ventilation and risks...
K2
I am sure you will have read many documents such as this,
https://www1.eere.energy.gov/hydrogenandfuelcells/tech_validation/pdfs/fcm03r0.pdf
But this one explains the point about crankcase ventilation and risks...
K2
Thanks GREEN-twin, Lovely to hear you ranting about the Green policies of "our dearly elected Government"... "Dearly" as in it costs us a fortune for "we know not what"...
Your rant is not out of place here. I agree with you.
Another political argument: You can stop Cows from farting if you don't have cows, but eat the grass instead..? (That's another political "pie-in-the-sky idea"). Then the people will fart more... or wear catalytic exhausts... ? Aha! Eliminate the people!
I simply try to avoid political comments and concentrate of providing the mish-mash of rubbish I call "my knowledge" - with hopefully some useful comment? - to answer the original question, and any associated issues.
(Knowledge" = You realise it is a position (to Know), with a demarcation line (the edge of the Ledge), beyond which "Unknown forces" (e.g. Gravity?) can drag you down to doom (you fall off the ledge with unknown consequences). - I.E. "know-ledge" is a safe place but very close to a dangerous place where it would seem crazy to risk going. But you really don't know the consequences of going "off the ledge"...)
I am glad someone (you and a few) read my stuff and bring some sense to it.
Thanks,
K2
Your rant is not out of place here. I agree with you.
Another political argument: You can stop Cows from farting if you don't have cows, but eat the grass instead..? (That's another political "pie-in-the-sky idea"). Then the people will fart more... or wear catalytic exhausts... ? Aha! Eliminate the people!
I simply try to avoid political comments and concentrate of providing the mish-mash of rubbish I call "my knowledge" - with hopefully some useful comment? - to answer the original question, and any associated issues.
(Knowledge" = You realise it is a position (to Know), with a demarcation line (the edge of the Ledge), beyond which "Unknown forces" (e.g. Gravity?) can drag you down to doom (you fall off the ledge with unknown consequences). - I.E. "know-ledge" is a safe place but very close to a dangerous place where it would seem crazy to risk going. But you really don't know the consequences of going "off the ledge"...)
I am glad someone (you and a few) read my stuff and bring some sense to it.
Thanks,
K2
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Using hydrogen in an IC engine video:
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Yes, I am afraid that if you translate the phrase "UK government published its Ten Point Plan for a Green Industrial Revolution", the actual definition is UK government comes up with a green plan, where nothing practical is achieve accept transferring the green in your wallet to the bank accounts of the politically well connected in the green (modern day snake-oil) shakedown industry.
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Luckily, our excellent government have found a way to grow hydrogen on trees so that it doesn't need to be made from natural gas, but there is another factor that needs to be considered. The density of liquid hydrogen is very low, so if your motorcycle has a 2 gallon / 10 litre fuel tank, you'll be needing a 20 gallon / 100 litre fuel tank for the same range on hydrogen. I can't see the problem myself.
Stupid of me. The volume of hydrogen means the return of sidecars (you can make one with a 20 gallon tank installed easily!) - or trailers that carry the fuel. If they had a quickly detachable or breakable link, then in the event of an accident the tank could be quick released - so the rider is well away from any risk of the tank blowing-up... Better than having 20 gallons of H2 right next to the family jewels?
K2
K2
Now then... thinking aside, with H2 fuel you can have a rocket engine.... or fuel cell and electric motor, ...?
K2
K2
