2 stroke thread (with occasional F1 relevance!)

[63l8qrrfy6]

& FYI, those sleeve valve aero-engines of 70-80 years ago..
..actually demonstrated oil consumption figures no worse, & often better than rival poppet valve aero-mills..

A quick google search says sabre was consuming 27l/hour while rr merlin up to (but often much less) 11.37 l/h.
Normalized by engine displacement (27 l for merlin and 36.6l for sabre), the oil consumption was over 70% higher. Even if you normalize even further by specific power it is still well over 60% higher.
These are the first engines that came to mind, I am sure there are examples where the difference is not as bad.

Manolis' argument was that the jumo was used in aircraft due to it's stellar oil consumption. My point was that oil consumption was not a major selection criterion and that far worse contemporary engines had flown.

[J.A.W.]

& FYI, those sleeve valve aero-engines of 70-80 years ago..
..actually demonstrated oil consumption figures no worse, & often better than rival poppet valve aero-mills..

A quick google search says sabre was consuming 27l/hour while rr merlin up to (but often much less) 11.37 l/h.
Normalized by engine displacement (27 l for merlin and 36.6l for sabre), the oil consumption was over 70% higher. Even if you normalize even further by specific power it is still well over 60% higher.
These are the first engines that came to mind, I am sure there are examples where the difference is not as bad.

Manolis' argument was that the jumo was used in aircraft due to it's stellar oil consumption. My point was that oil consumption was not a major selection criterion and that far worse contemporary engines had flown.

M-f, I think the advantage for CI/heavy fuel engines is a combination of fuel consumption & fuel power density..

Edit/adit: Here's a 'Flight' technical appraisal of the 2T CI Napier Nomad aero-engine..
https://www.flightglobal.com/pdfarchive ... 01220.html

& a quick check of Wilkinson's 1947 'Aircraft Engines of the World' - gives oil consumption figures for
the Sabre VII as "6g/hp/hr" VS R-R Griffon 65 at "10g/hp/hr", both being ~36 litre liquid cooled inlines..

[63l8qrrfy6]

M-f, I think the advantage for CI/heavy fuel engines is a combination of fuel consumption & fuel power density..

I completely agree. I was only disputing the oil consumption claims.


& a quick check of Wilkinson's 1947 'Aircraft Engines of the World' - gives oil consumption figures for
the Sabre VII as "6g/hp/hr" VS R-R Griffon 65 at "10g/hp/hr", both being ~36 litre liquid cooled inlines..

After looking a bit into the oil consumption of that time, I realized it's simply impossible to draw parallels to modern engines. The oil consumption nowadays is orders of magnitude better. For Manolis to claim that his engine will perform well in this respect based on comparisons to the jumo is simply ridiculous.

[J.A.W.]

Not "impossible", it has been claimed that current F1 engines ( non-emissions constrained, like aero-engines),
consume ~5 litres of oil per race, so a g/hp/hr calculation on that basis will allow comparison..

[63l8qrrfy6]

M-f, I think the advantage for CI/heavy fuel engines is a combination of fuel consumption & fuel power density..

I completely agree. I was only disputing the oil consumption claims.


& a quick check of Wilkinson's 1947 'Aircraft Engines of the World' - gives oil consumption figures for
the Sabre VII as "6g/hp/hr" VS R-R Griffon 65 at "10g/hp/hr", both being ~36 litre liquid cooled inlines..

After looking a bit into the oil consumption of that time, I realized it's simply impossible to draw parallels to modern engines. The oil consumption nowadays is orders of magnitude better. For Manolis to claim that his engine will perform well in this respect based on comparisons to the jumo is simply ridiculous.

Also neither were inlines, one was a H and the other a V..

[J.A.W.]

FYI M-f, in aero-engine usage, a longitudinally arranged crankshaft/cylinder mill is an 'inline',
regardless of how many banks are utilized, to differentiate from 'radial' engines..

(albeit, things get a bit melded with the odd-ball asterisk configured Jumo 222, described as a 'radialine')..

[manolis]

Hello Mudflap

You write:

“Again, the 'it was decent 80 years ago' argument' - let's put this to rest - 80 years ago they flew sleeve valves which had an impressively high oil consumption - does that make them good too ? If you want to make a good case let me know how much oil the jumo burned and let's see how it compares to modern engines.

(Manolis: ) Your theory relating the “sealing efficiency” with the number of holes / ports on the cylinder liner needs amendments.

It's not my theory - these are published results.”




An engine which is “rubbish at sealing” cannot achieve 37.5% working BTE (especially when it is based on an 80 year old technology and materials, on simple mechanical control, on low pressure injection system, on disk-shaped combustion chamber, etc).

A poor sealing would cause an excessive leakage at the high pressure period of the cycle.
Especially at the lower revs.
However, in the BSFC plot of the Junkers Jumo 205D it “writes”: 37.5% BTE maintained from above 2,400rpm to below 1200rpm (wherein the time for leakage is more than double):



Excessive leakage of compressed air causes, among others, significant energy loss and drop of the BTE.



The typical (non opposed piston) giant 2-stroke marine engines (like the Wartsila TRA96C and the Wartsila X92) have some two dozens of ports in the lower side of each cylinder:



If they had problematic sealing efficiency (i.e. if they were “rubbish at sealing”) they could not achieve, running at extremely low revs (say, at 70rpm, i.e. as much a man’s heart beats), more than 50% BTE.


Either “the published results” you claim are wrong, or you understand / translate them the wrong way.

Thanks
Manolis Pattakos

[manolis]

Hello all

Manolis wrote:
“By the way, I am waiting for your “description” of what is happening with the lubricant when the piston abuts heavily on, and slides along, the port openings of a 2-stroke.”

Mudflap replied:
“It craps itself with or without the presence of thrust loads.”




Let’s suppose Mudflat is right.

I.e. that when the piston skirt moves, with or without thrust loads, over the ports of the cylinder liner, it is the same (there is no difference)



Here is a simpleminded question:


What is the difference (regarding the lubrication and the lubricant consumption) when:

a piston (of a ported “cross-head” two-stroke) moves, without thrust loads, over the ports of the cylinder liner,

and when:

a Bishop rotary valve (of a 4-stroke engine) moves inside the cylinder head.


In both cases there are ports / openings (on the cylinder liner, in the first case, on the rotary valve, in the second case) and sealing means passing over the ports.



If the Bishop rotary valve:



does not consume lubricant, the same is the case for the pattakon OPRE:



and PaTOP:



cross-head 2-stroke engines.



If the Bishop cannot help running at high specific lube consumption, then the PatRoVa rotary valve (which runs “dry”) can solve the problem (viable and promising solution).


So,
Mudflat and Muniix should “talk” with each other to decide which of the two happens.


Either way, pattakon has a solution.

Thanks
Manolis Pattakos

[manolis]

Hello Mudflat

You write:

“Piston skirts have a carefully designed 'barrel' profile which facilitates hydrodynamic film generation.
NOT being flat is what makes them work in the first place.”



According your “theory” the “barrel” profile (like the small barrels at the sides of the PatOP:



in the above video-animation) is better.


According the practice you are wrong: is there anything that prevents MAN and Wartsila from using it instead of the current cross-head with the flat sliders and the flat slide-ways?




By the way:

Besides their cross-head 2-stroke engines, they also produce normal trunk piston 4-stroke engines, so they know both “worlds” from inside.
However they do not use “carefully designed 'barrel' profile which facilitates hydrodynamic film generation” in their 2-strokes.



You also write:
“Your understanding of fundamental principles is flawed.”

! . . .

Thanks
Manolis Pattakos

[manolis]

Hello all.

Here is the “in-cylinder-flow” :



(if the image is not clear click on: http://www.pattakon.com/tempman/In_Cyli ... mmetry.gif )


The gas flow is shown only in the one half of the cylinder.

The gas flow in the other half of the cylinder is identical (mirrored about the bisecting plane).

The velocities of the gas molecules that are on the bisecting plane are parallel to the bisecting plane (zero velocity normal to the bisecting plane).

It is like having an “imaginary curtain” separating / isolating the cylinder in two halves: the one half fills by the gas entering though the one intake valve, the other half fills by the gas entering through the other intake valve.

If this “curtain” was real, it would spoil the flow (boundary layer friction), because in such a case the molecules on the bisecting plane should have zero velocity.




The PatRoVa rotary valve:



is perfectly symmetrical.

There are two tangential gas streams (one per chamber port), the one filling the one half of the cylinder, the other filling the other half of the cylinder (the one abutting on the other).

And because they are symmetrical, they do not interfere with each other.




Thanks
Manolis Pattakos

[63l8qrrfy6]

An engine which is “rubbish at sealing” cannot achieve 37.5% working BTE (especially when it is based on an 80 year old technology and materials, on simple mechanical control, on low pressure injection system, on disk-shaped combustion chamber, etc).

I have never said that the engine losses compression - By sealing I clearly meant oil that makes its way into the cylinder. I thought that was pretty obvious.

What is the difference (regarding the lubrication and the lubricant consumption) when:

a piston (of a ported “cross-head” two-stroke) moves, without thrust loads, over the ports of the cylinder liner,

and when:

a Bishop rotary valve (of a 4-stroke engine) moves inside the cylinder head.


In both cases there are ports / openings (on the cylinder liner, in the first case, on the rotary valve, in the second case) and sealing means passing over the ports.

I don't know what the oil consumption of the bishop valve nor that of a wartsila engine is. And neither do you. How these engines relate to yours is beyond me.

According the practice you are wrong: is there anything that prevents MAN and Wartsila from using it instead of the current cross-head with the flat sliders and the flat slide-ways?

How do you know ? Do you have engineering drawings of either of those engines ? The profile has sub-millimeter deviations from flat - how can you tell it's not profiled from those images ?


Your only arguments seem to consist of spamming the same pictures and animations over and over again. I am pretty sure you have posted some of them dozens of times already. You've based your designs on a bishop rotary valve, a wartsila engine and a ww2 engine and claim it has the same advantages as all of them with none of the cons.

I've googled pattakon and you seem to have been spreading the same false claims all over the internet for the last 15 years! The only tangible evidence you have produced is a couple videos of running engines grinding themselves to death, stop motion animations of some badly made components on a chair and ms paint simulation of in cylinder flow, and masses of internet images that do not even remotely relate to your designs.
On a certain forum you even boasted you will make millionaires out of potential investors!

I have been very patient in trying to explain why I think certain aspects of your engines are lacking. Instead of trying to understand my arguments you have continued to deflect and draw parallels to loosely related engines you don't know much about.

It is obvious that you cannot handle criticism and are here just to promote yourself. You lack a basic understanding of fundamental engineering principles and do not show any interest at all in trying to comprehend these. I do not think your claims are ill-intended, however you are clearly deluded by the potential of these engines.

I sincerely thought that my criticism will be constructive - that is obviously not the case. GG suggested that you might need engineering support. He was wrong as you seem to know everything there is to know and your engines are perfect.

As these one-sided arguments are a waste of both of our time I will stop here and wish you all the best in your endeavors.

[J.A.W.]

...Your only arguments seem to consist of spamming...

...I sincerely thought that my criticism will be constructive - that is obviously not the case...

...I will stop here and wish you all the best in your endeavors.

Seriously M-, I agree.. ..with that final bit..
& I'd reckon you'd indeed be best to refrain from any further posting here.. ..at least..
..until you can check/parse your needlessly emotive over-reaction/over-familiarity..
..lose the all too evident 'projection'/'passive-aggressive' tone, & stick to a cooly technical approach..

[gruntguru]

I am sure this is not a deliberate attempt to mislead and you simply overlooked the fact that the extra piston contributes its own displacement, so oil consumption as a function of engine displacement remains the same were you to substitute the opposing piston with a cylinder head.

A cylinder head that leaks oil, yes.

No - a cylinder head that leaks no oil. Think about it and see your mistake before critiquing the engineering abilities of others.

[manolis]

Hello all.


Manolis wrote:
“An engine which is “rubbish at sealing” cannot achieve 37.5% working BTE (especially when it is based on an 80 year old technology and materials, on simple mechanical control, on low pressure injection system, on disk-shaped combustion chamber, etc).

Mudflat replied:
“I have never said that the engine losses compression - By sealing I clearly meant oil that makes its way into the cylinder. I thought that was pretty obvious.”



QUOTE from http://achatespower.com/oil-consumption/

Achates Power

Oil Consumption Measurements for a Modern OP2S Engine



by Dr. Brian Callahan
Senior Development Engineer, Achates Power, Inc



March 8, 2012

Modern, four-stroke on-highway diesel engines typically have fuel-specific oil consumption (FSOC) in the range of 0.075-0.15%, with the best-in-class engines demonstrating oil consumption as low as 0.05% of fuel. These engines also have the advantage of being compatible with various aftertreatment devices. Two-stroke engines, however, have historically demonstrated FSOC of between 0.25-0.60%. The Achates Power achievement of 0.18% FSOC across the entire operating map is lower than any opposed-piston or two-stroke diesel engine ever reported in open literature, and we are continuing our development work to reach a weighted average of 0.05-0.10% FSOC—matching the best-in-class, four-stroke engines.”

End of QUOTE


Until 2012 (i.e. when the above article of Achates Power was published and commended) Achates Power was using the two-side-crankshafts design:







which eliminates the thrust loads between the piston skirt and the cylinder liner.

Despite the big number of intake and exhaust ports at the two ends of each cylinder, the specific lubricant consumption was measured, as they claim, to be the lowest among the 2-stroke engines and just a little higher than that of the 4-stroke Diesels.



Accordingly, the theory that relates the number of ports on the cylinder liner with the “oil that makes its way into the cylinder” is wrong.

Thanks
Manolis Pattakos

[manolis]

Hello all.


Manolis wrote:
“What is the difference (regarding the lubrication and the lubricant consumption) when:
a piston (of a ported “cross-head” two-stroke) moves, without thrust loads, over the ports of the cylinder liner,
and when:
a Bishop rotary valve (of a 4-stroke engine) moves inside the cylinder head.
In both cases there are ports / openings (on the cylinder liner, in the first case, on the rotary valve, in the second case) and sealing means passing over the ports.”


Mudflap replied:
“I don't know what the oil consumption of the bishop valve nor that of a wartsila engine is. And neither do you. How these engines relate to yours is beyond me.”


QUOTE from http://www.pattakon.com/pattakonPatMar.htm

“The problem as defined in Wartsila's(*) Technical Journal, Feb 2010 (click http://www.pattakon.com/tempman/Wartsil ... 2_2010.pdf )

"A slightly more ambitious idea is to apply the four-stroke trunk piston engine cylinder lubrication concept to the two-stroke crosshead engine, i.e. to "over-lubricate" the cylinder liner, apply an oil scraper ring, and then collect the surplus oil, clean it, and recycle it. This will of course be a radical change of concept, and whether or not it is viable remains to be demonstrated, but an outline exists and a patent is pending. The aim is to increase scuffing resistance and to achieve the same low specific oil consumption level as on the four-stroke trunk piston engines."

End of QUOTE

The PatMar engine presented at the above link is the only solution, so far, of the problem.




Manolis wrote:
“According the practice you are wrong: is there anything that prevents MAN and Wartsila from using it instead of the current cross-head with the flat sliders and the flat slide-ways?”
Mudflap replied:
“How do you know ? Do you have engineering drawings of either of those engines ? The profile has sub-millimeter deviations from flat - how can you tell it's not profiled from those images ?”


All the giant marine (and electric power generation) 2-strokes use the flat cross-heads.
The internet is full of such designs (just get into Wartsila’s web site and download hundreds of PDFs showing slat-cross-heads).

If you know one using “barrel” cross-head show it here.




Mudflat wrote:

“Your only arguments seem to consist of spamming the same pictures and animations over and over again. I am pretty sure you have posted some of them dozens of times already. You've based your designs on a bishop rotary valve, a wartsila engine and a ww2 engine and claim it has the same advantages as all of them with none of the cons.

I've googled pattakon and you seem to have been spreading the same false claims all over the internet for the last 15 years! The only tangible evidence you have produced is a couple videos of running engines grinding themselves to death, stop motion animations of some badly made components on a chair and ms paint simulation of in cylinder flow, and masses of internet images that do not even remotely relate to your designs.”


Everything is relative.

The EcoMotors OPOC and the Achates Power Diesels are relative to the OPRE, PatOP and PatPOC opposed piston engines.

The Cross-Watson-Bishop rotary valve is relative to the PatRoVa rotary valve.

The PatAir is relative to the MultiAir of FIAT / Chrysler / Alfa Romeo / Schaeffler-INA.

The DVVA is relative to Ducati’s DESMO.

The pattakon VVA’s are relative to BMW’s valvetronic, to Honda’s VTEC, etc.

The PatMar is relative to Wartsila’s marine 2-strokes.

The PatWankel is relative to the Wankel and to the Liquid piston engines.

The constant velocity joint of pattakon is relative to the TCVJ.


EcoMotors with one only project (OPOC engine) is in the Internet for 20 years and thousands of articles have been written about the OPOC so far.


Thanks
Manolis Pattakos