2 stroke thread (with occasional F1 relevance!)

[Tommy Cookers]

[quote=Pinger]
RE crevice volume. Depends what certification you seek. Bristol obviously didn't have current motoring emission regs in mind. I do. And reducing crevice volume to a minimum is highly desirable if not absolutely essential.[/quote]

Bristol/Fedden designed/made prototypes eg the 'F-car' (English intentions as VW concept) from 1943-1947
the F-Car 1.Ex had a rear 1500cc 3 cyl sleeve valve radial with vertical crankshaft driving a (gearless ?) torque converter transmission
and the faults acquired by visiting Wolfsburg in 1945 plus faults due to the engine, which looked like something from industrial breadmaking
eventually after a classic early-type swing-axle crash it was abandoned for upmarket design attempts, then Roy Fedden Ltd was liquidated in April 1947

[Muniix]

Hello Pinger.

How can you achieve asymmetric transfer timing with conventional piston and rod?

How much "asymmetrical"?

A drawing, animation or explanation would help.

Thanks
Manolis Pattakos

Yesterday's run was with transfers timed at approximately 45deg ABDC. A no load test, it is the slowest idling I have achieved with it thus far. It is a 40cc Zenoah 1400 engine (from a strimmer I think) I'll leave you to guess how the assymmetry is achieved (very simply).
Not convinced I am on the right path though so currently rethinking my strategy.

PS.
Heat path for a plug is from plug via thread to threaded boss. The boss requires cooling.
Narrow passages in a combustion chamber can be expected to become blocked with carbon. They seldom disappoint!

Manolis refuses to acknowledge any issues raised with his designs, does the usual straw man of "don't look there - look over here"

I've explained the area around the spark plug is the hotest part of the head and he replied with;

"but don't you see how ..."

None of his designs take into consideration the cooling requirementsm so none are production ready, just waiting to fail on endurance or heat cycle testing.

He focues on one percieved issue and compromises all the others with his change, and before he has even verified if the issue is real, doesn't use the available technology to help with CAE.

Doesn't seem to understand fluid dynamics, acoustic or thermal issues or the combustion process but believes the popular myths and exploits peoples gullibility.

He will be off on another forum doing the same thing on at least half a dozen other forums now. He must be one of triplets with the prolific forum postings. Repeating the same even though someone has pointed out issues, he just ignores what is inconvenient.

He should stick to his poppet valves and variable desmodromic actuation. He has something there, seems proven according to him. Get that into production and use royalties like Bishop did to fund further innovation and employ some un- opinionated engineer who can call out his opinionated BS.

[Muniix]

I thought the PWS (initially called Comprex) was abandoned due to it overheating the incoming air. (Not by compression, but by proximity to the outgoing exhaust gas).

The compressed air charge goes through an intercooler same as with a turbo. It has less cooling and lubrication requirements than a turbo does. It can also have the rotor coated to perform catylitic duties, especially on lean burn engines that have no NOx it can convert the co to co2 and you meet emissions. Its a device to improve efficiency and provide boost from just off idle and up, Someone created a controller for constant torque through the whole rpm range with one.

Someone should take it up and improve it for Jet Ignition, put a MGU-h in with it. It works better on smaller engines with less cylinders as it needs a pressure wave to kick it off. Running one or two cylinders with Jet ignition at 2 bar ultra lean and the ideal external egr you have a very efficient power plant capable of providing from 30kw to 300 at very high efficiency with low cooling requirements.

It is more for combustion thermodynamic efficiency, you can control boost very effectively, fast response no lag, and control the amount of boost and egr to achieve maximum TE very quickly.



Did you read that researchers have produced microbes that produce propane from carbohydrates and sun light. So five to ten years comercal production of a good fuel source. Plug in your hybrid and fill its pressure vessel from home, what service station.

Additionally it doesn't need cooling, spins only to 30,000 or complex lubrication requirements.

It does need some compute and pressure temperature sensors on all four ports, an electric motor to trim rotor speed a second throttle valve, and the gas bypass valve to limit boost.

But the simplified physics models used to control it can be used to control the IC engine with fully closed loop operation..

Sensata have a cylinder only pressure sensor for production engines, BMW and Daimler are soon to introduce engines with them. This provides data at 15k samples a second, not every degree at high engine speed but a simplified model running with it can fill in the blanks inbetween based on kistler pressure sensor data during engine development to calibrate the model.

With up to 1,000 giga flops of compute for $20 you can implement many virtual sensors. Providing useful data for better engine management, eliminating fuel maps, calculating heat flux into liner to operate electric coolant pump for constant temperature, improving efficiency.

Researchers have achieved 56% TE with ethanol at 1.7 bar and 90 Celsius intake, 17.3:1 CR, and 33%egr with a lambda of 1.7 fuel equivelence ratio.

Marc

[Pinger]

Muniix:
It seems the PWS was retired too early. When there is a rush of new technology, one tends to dominate and others are abandoned never to see any development (that may result in them being superior). In this context, the rush to turbochargers (a relatively known technology - always the trend in the auto industry) with the rise of common rail diesel saw the PWS sidelined. The advance of electronics appear to have given it a second wind...
Similarly - T.Jet ignition. I was looking into similar way back - then common rail diesel arrived and swept all aside. TJet ignition is an old technology which falls under the rubric of 'torch ignition'. No one - despite plenty trying - made much of a success of it. I'm genuinely surprised to see its return, though in the context of lean burn, perhaps inevitable.

[Muniix]

Muniix:
It seems the PWS was retired too early. When there is a rush of new technology, one tends to dominate and others are abandoned never to see any development (that may result in them being superior). In this context, the rush to turbochargers (a relatively known technology - always the trend in the auto industry) with the rise of common rail diesel saw the PWS sidelined. The advance of electronics appear to have given it a second wind...
Similarly - T.Jet ignition. I was looking into similar way back - then common rail diesel arrived and swept all aside. TJet ignition is an old technology which falls under the rubric of 'torch ignition'. No one - despite plenty trying - made much of a success of it. I'm genuinely surprised to see its return, though in the context of lean burn, perhaps inevitable.

TJI was developed here in Australia at Melbourne University by Dr. William Attard who worked on the Bishop team for a few years before he went off to do his PhD. My guess is it was the clever way Bishop used the two offset plugs with squish and the dual cross tumble flow to create the huge central flame kernel and the improvement to combustion that provided that inspired him to work on combustion Ignition to improve engines.

Mark Boxsell from the Bishop team now specialises in the ignition controllers providing ignition systems for everything F1, Nascar, Supercars, drag bikes and cars. Everyone rebadged his M&W ignition hardware.

The ideal companion technology for the Bishop valve, providing lower temperature helps the valve while the valve provides the extra air flow for ultra lean heat dilution combustion.

Mahle imployed Bill in the UK to produce Mahle Jet ignition. Ultra lean improves pumping efficiency at low loads you can run dethrottled especially with LPG.

That's how they achieved 56% TE with ethanol and 1.7 fuel equivalence ratio using a sub optimal engine geometry.

Originally based on Professor Harry Watson HAJI.

Mercedes implemented it in 2013 in there F1 power plant and then dominated.

Mahle have cought up with their knowledge and experience. Bills wife is a thermo dynamics physics and does a lot of the research on it.

It's the future for IC engines needing Ignition. Can't see any point using SI anymore, you have to deal with greater heat, acoustic forces, extra cooling and reduces the choice in materials you can use in engine construction.

A engine design optimised for TJI would need to be re-engineered for SI, loose the efficiency and steel piston it allows you to use. Steel liners provide efficiency advantages if you control temperature.

[manolis]

Hello Muniix.

You write:
“I was talking about using gas pressure
as the sole means for seal force?

you did not answer that!

The PatRoVa has massive leakage which is equivelent to crevice volume, your whole valve housing is crevice volume.”


The answer is:

The PatRoVa rotary valve “is not using gas pressure for sealing”.

The PatRoVa rotary valve seals by keeping tiny the clearance between the chamber port lips and the opposite acting fronts of the rotary valve.


QUOTE from the beginning of the http://www.pattakon.com/pattakonPatRoVa.htm web page:

“What the rotary valve does need is a very strong "body" to "connect" the oppositely acting fronts; so strong that the heavy loads applied on the fronts to cause no more than an insignificant deformation of the rotary valve and thereby to keep into the required strict limits the clearance between the chamber ports and the rotary valve fronts (wherein the sealing happens).





Accordingly, a rock-solid structure for the rotary valve is essential; but this is not an issue because the rotary valve performs a smooth rotation at half crankshaft speed; even a substantial increase of the rotary valve mass and inertia is tolerable; in comparison a small increase of the reciprocating mass of a poppet valve causes major side effects.”

END of QUOTE




You also write:
“As detailed you have too many inherent flaws in the design as previously raised, sealing, insufficient flow, loss of pressure wave action, increased pumping losses, thermal issues ....
Trying to solve the non issue of combustion pressure, you split the flows and turned them into one another.
Loosing valuable flow capacity and reducing the flow coefficient many times on an already low flow. Introducing fluid flow issuesj that only 3D CFD while allow you to understand, and it will be complex to implement the motions of the valve into the simulation.”

Are you ready to bet on what you claim?
You have my “bet” e-mail from January.




You also write:
“That is mischevious refering to an obsolete patent, lodged in for patent protecion, it can be used in motorsport, that one is not the latest sealing patents Bishop filed. Remember I gave you the latest one, Cameron Donalds patent. The one that solves all the issues with clever overlapping. It identifies all the issues that a sealing array must provide and addresses them providing everthing the seals need to do. It shows all the paths, and flows, and the mechanisms used to address them.”


Nonsense.

The “mischevious refering” is nothing more than what the inventors write in “their” US7,621,249 patent.

Are you representing the inventors or the assignee?

Are you authorized to classify Bishop patents in good ones and bad ones?


The “legacy” of the “Bishop Innovation Limited” is their patents. Don’t spoil it.


You claim you know the guys of the Bishop team.
If so, ask Anthony Bruce Wallis to get in this discussion.

Thanks
Manolis Pattakos

[Muniix]

Hello Muniix.

You write:
“I was talking about using gas pressure
as the sole means for seal force?

you did not answer that!

The PatRoVa has massive leakage which is equivelent to crevice volume, your whole valve housing is crevice volume.”


The answer is:

The PatRoVa rotary valve “is not using gas pressure for sealing”.

The PatRoVa rotary valve seals by keeping tiny the clearance between the chamber port lips and the opposite acting fronts of the rotary valve.


QUOTE from the beginning of the http://www.pattakon.com/pattakonPatRoVa.htm web page:

“What the rotary valve does need is a very strong "body" to "connect" the oppositely acting fronts; so strong that the heavy loads applied on the fronts to cause no more than an insignificant deformation of the rotary valve and thereby to keep into the required strict limits the clearance between the chamber ports and the rotary valve fronts (wherein the sealing happens).

http://www.pattakon.com/PatRoVa/PatRoVa_photo11F.jpg

http://www.pattakon.com/PatRoVa/open_end_wrench.jpg

Accordingly, a rock-solid structure for the rotary valve is essential; but this is not an issue because the rotary valve performs a smooth rotation at half crankshaft speed; even a substantial increase of the rotary valve mass and inertia is tolerable; in comparison a small increase of the reciprocating mass of a poppet valve causes major side effects.”

END of QUOTE

You have clearly not performed thermal and fea analysis on the valve. Thermal expansion will effect it, you have no cooling in the head. . .

You also write:
“As detailed you have too many inherent flaws in the design as previously raised, sealing, insufficient flow, loss of pressure wave action, increased pumping losses, thermal issues ....
Trying to solve the non issue of combustion pressure, you split the flows and turned them into one another.
Loosing valuable flow capacity and reducing the flow coefficient many times on an already low flow. Introducing fluid flow issuesj that only 3D CFD while allow you to understand, and it will be complex to implement the motions of the valve into the simulation.”

Are you ready to bet on what you claim?
You have my “bet” e-mail from January.

Pumping capacity and intake velocity alone are major issues. You can't defy physics. What is the intake velocity for a Superquatro Implementation, i.e. 642 cc per cylinder @ 9,800 rpm peak power.

Easy enough to calculate, trapped air mass required per cycle.

The “mischevious refering” is nothing more than what the inventors write in “their” US7,621,249 patent.

Are you representing the inventors or the assignee?

Are you authorized to classify Bishop patents in good ones and bad ones?

The “legacy” of the “Bishop Innovation Limited” is their patents. Don’t spoil it.

You claim you know the guys of the Bishop team.
If so, ask Anthony Bruce Wallis to get in this discussion.

Thanks
Manolis Pattakos

Clearly you do not understand the patent protection system, you patent all the implementations​. To prevent someone releasing a inferior Implementation and damaging the reputation of your Innovation.

The patent you reference is prior art patents only. Protection from someone​ producing a bad valve.

I'm not telling anyone to do anything, especially to engage with someone who has no grasp of reality.

You think it's viable to spend millions to sell a few motorcycle heads for crf 450 owners, who can't use them on the road or competition. Hmm that will be $20k+ per head, minimum and still make a loss.

[Pinger]

Mercedes implemented it in 2013 in there F1 power plant and then dominated.


A engine design optimised for TJI would need to be re-engineered for SI, loose the efficiency and steel piston it allows you to use. Steel liners provide efficiency advantages if you control temperature.

Thanks for the post Muniix.
Picking up on the above. Mercedes alone adopted TJI (not Ferrari, Renault)?

I noticed the reference to lean burn. Is that the real benefit of TJI, lighting off lean mixtures (a spark alone can not)? And the reference to LPG - because of its lower lean flammability limit relative to petrol?

Not getting the steel piston reference. Is this a feature of the Mercedes F1 unit - or something else entirely?

[Muniix]

Mercedes implemented it in 2013 in there F1 power plant and then dominated.

A engine design optimised for TJI would need to be re-engineered for SI, loose the efficiency and steel piston it allows you to use. Steel liners provide efficiency advantages if you control temperature.

Thanks for the post Muniix.
Picking up on the above. Mercedes alone adopted TJI (not Ferrari, Renault)?

I noticed the reference to lean burn. Is that the real benefit of TJI, lighting off lean mixtures (a spark alone can not)? And the reference to LPG - because of its lower lean flammability limit relative to petrol?

Not getting the steel piston reference. Is this a feature of the Mercedes F1 unit - or something else entirely?

The main advantage is lean operation, if you reduce to a FE of 1.85 with typically rod ratio you burn slower and cooler dropping from 2550 Celsius to around 1800 from memory. You eliminate the rotational and vibrational moles, production of oxides of nitrogen and many nasty cancer causing elements, like OH-, these contribute nothing to cylinder pressure, so with less fuel you can generate more torque depending on crankshaft geometry, crank rod angle at peak Pressure. Reducing bearing friction at TDC and torsional issues. You now have lots of strategies available whereas with SI it's lit and everything is predetermined. Hence a cylinder pressure sensor real or virtual to maximize engine power and efficiency.

Now you have lower temperature, steel pistons become a possibility and there advantages.

Mahle are Ferrari technology partner so Ferrari have TJI and steel pistons from Melbourne this year. Hence they have cought up to Mercedes now. Some say Mercedes lured one of Bills team to Implement jet ignition early. So 46% TE is currently achieved.

[Pinger]

Thanks Muniix (for bringing me up to speed here).
Not quite there though!
OK, lean burn for the lower temp (less heat loss and lower NOx), unthrottled running (lower pumping losses), slower combustion (lower peak pressure/friction), but does slower combustion not increase heat loss?

Why do steel pistons require lower combustion temps - lower thermal conductivity and an increase in tendency toward detonation? And what advantage(s) do they possess? (I am aware of their use in diesels for their strength under prolonged high pressure - same here?)

PS. If this has already been covered in the forum my apologies for incurring repetition. Just found this forum a fortnight ago and took a week to read through this thread. The rest of the forum so far is too much to dive into right now.

PPS. Good to see valid reasons for Ferrari's renaissance. Not just a flash in the pan but performance that can be expected to endure throughout the remainder of the season. The sport needs that!

[Muniix]

Thanks Muniix (for bringing me up to speed here).
Not quite there though!
OK, lean burn for the lower temp (less heat loss and lower NOx), unthrottled running (lower pumping losses), slower combustion (lower peak pressure/friction), but does slower combustion not increase heat loss?

Ahh, now I have to get detailed. Another advantage is the jets are targeted to the outside and burning towards the centre. So reduced heat loss. Area in contact with burned and unburned gas add to the design complexity, bore to stroke ratio, liner temperature, heat flux, barrier layer, surface having a fast in slow out gas flow behaviour.

They supports an increase in CR of 2 points or more. I've chosen a dual crank arrangement with two rods, this gives 192 degrees of intake due to offset and faster compression for greater turbulent kinetic energy then after TDC the rods becoming more vertical slowing expansion assisting combustion while crank is rotating extracting work then from 30 degrees on there is a constant flat line on the piston position graph for 100 degrees. So bearing friction loss simulation shows it's all good. Pressure volume graph and crank rod angle impressive, extracting energy from the introduced fuel, the compression effort is increased as energy must be conserved but pressure is lower so you win that one.
Then you can do multi phase combustion, burning extra fuel and air available from ultra lean.

Why do steel pistons require lower combustion temps - lower thermal conductivity and an increase in tendency toward detonation? And what advantage(s) do they possess? (I am aware of their use in diesels for their strength under prolonged high pressure - same here?)

PS. If this has already been covered in the forum my apologies for incurring repetition. Just found this forum a fortnight ago and took a week to read through this thread. The rest of the forum so far is too much to dive into right now.

PPS. Good to see valid reasons for Ferrari's renaissance. Not just a flash in the pan but performance that can be expected to endure throughout the remainder of the season. The sport needs that!

Steel pistons were the holy grail, until jet engines took over for larger bores they are lighter and better fitting, less noise and rocking moment. Compatible with thermal barrier coating better than AlSi.

Cooling is the issue, oil will crack at combustion temperatures, squirting oil from underneath doesn't remove heat due to oil being removed to quickly. So it's up to oil from rod, cooling during intake duration, conduction via compression rings with the current trend being 0.8-1.2 mm profiled rings with DLC coatings that path is reduced.

Suggest you read some of the papers, early ones and later ones on identifying start of combustion via pressure sensors is different to SI.

[langwadt]

Muniix:
It seems the PWS was retired too early. When there is a rush of new technology, one tends to dominate and others are abandoned never to see any development (that may result in them being superior). In this context, the rush to turbochargers (a relatively known technology - always the trend in the auto industry) with the rise of common rail diesel saw the PWS sidelined. The advance of electronics appear to have given it a second wind...
Similarly - T.Jet ignition. I was looking into similar way back - then common rail diesel arrived and swept all aside. TJet ignition is an old technology which falls under the rubric of 'torch ignition'. No one - despite plenty trying - made much of a success of it. I'm genuinely surprised to see its return, though in the context of lean burn, perhaps inevitable.

TJI was developed here in Australia at Melbourne University by Dr. William Attard who worked on the Bishop team for a few years before he went off to do his PhD. My guess is it was the clever way Bishop used the two offset plugs with squish and the dual cross tumble flow to create the huge central flame kernel and the improvement to combustion that provided that inspired him to work on combustion Ignition to improve engines.

isn't tji really just a modern fuel injected version of Hondas +40yo CVCC ?

[63l8qrrfy6]

I have to take Muniix's side on this.
I don't know nor care what has happened between you two, but he has a very strong point:

Engine design begins with cycle simulations which yield performance figures as well as thermal and mechanical loads. These are followed by several iterations of performance and mechanical simulations to establish the finer geometrical details.

Preliminary calculations excite me way more than flashy CAD and animations. I really do not intend to insult anyone but without significant effort put into simulations this is just a pointless 3D modeling exercise.

[J.A.W.]

It appears that very little content indeed - of most recent posts - is relevant to the thread topic.
Marc/Muniix also needs to 'cool his jets', & refrain from directing emotive personal comments at members here.

So: now a topical post, a 2T triple snowmobile engine powered Mazda MX-5 budget endurance racer..

http://blog.caranddriver.com/lemons-goo ... oke-miata/

[gruntguru]

Folks need to concentrate on things they do well. The things Manolis does well he does VERY well. Munix has identified himself as a naysayer. Manolis has presented a rough conceptual idea which solves many of the enduring issues plaguing rotary valves. He then gets abuse and ridiculous criticisms of issues which may or may not be genuine problems and may or may not have simple solutions.

For example - flow. The Pat RoVa clearly lacks the unbelievable flow capabilities of the BRV. OTOH it is easy to see that the flow area and discharge coefficients could with development, be comparable to your typical pent-roof head.

Combustion chamber. The Pat RoVa has an excellent SI combustion chamber design. Better than any rotary or poppet valve engine.

Leakage. Manolis has explained the sealing arrangement and how leakage gases are handled. He could be right. If not, a face seal with no exposure to the combustion chamber could be added quite easily.