Small engines with a focus on improved fuel economy and emissions?

[Street Ryderz]

An expansion chamber will not eliminate short circuiting. Proof is that conventional 2 strokes with expansion chambers still have very high HC emissions.



This video does not discuss short circuiting in any way shape or form.

The video explains the precise timings required for the waves effects to come into play and as I said above or below this point where the cylinder is over filled it's left short circuited, The very high emissions are really only at idle and part throttle as stated above this is why emission tests are done in this rpm range NOT at high rpm or on the pipe where most would pass just fine!
This is what I mean you need to understand this stuff better because trust me it won't be you reinventing this wheel! LOL

 

[87Octane]

Wow get a clue! you say "It air-fuel that flows from the transfer port directly into the exhaust. It is not involved with scavenging". yet your example diagram clearly states Schematic drawing of SCAVENGING FLOW to illustrate the short circuiting and what is shown as the scavenging port is the transfer port, scavenging is a action of the flow not a physical thing so that diagram is not even correct!

When the air-fuel comes out of the transfer port (also called a scavenging port) ideally it all of it would flow onto the backside of the cylinder wall and then loop past the combustion chamber before coming back down to the exhaust port. That would be perfect scavenging (i.e. no short circuiting).

Any air-fuel that does not start the scavenging circuit and instead flows directly into the exhaust is the air-fuel that is "short circuit".

At full throttle it could be that 80% of the air-fuel immediately coming out of the transfer port begins the scavenging circuit and 20% of the air immediately coming out short circuits. Then maybe this changes to 65% and 35% at some lower throttle setting.

It is not an all or nothing event. Simultaneously you will have air-fuel flowing in the right direction and while other air-fuel is flowing in the wrong direction (i.e. the air-fuel that short ciruiting).

This is demonstrated in the picture where we see air-fuel headed in the right direction and air fuel headed in the wrong direction at the same time. This results in the exhaust never being pure exhaust gas (it always has some air-fuel in it) in a conventional 2 stroke engine.

 

[87Octane]

This video does not discuss short circuiting in any way shape or form.

The video explains the precise timings required for the waves effects to come into play

It explains wave effects, but not short circuiting.

Notice at this point in the video he does not mention that some intake flow goes immediately into the exhaust when the transfer port opens:

 

[Chainlube]

It explains wave effects, but not short circuiting.

Notice at this point in the video he does not mention that some intake flow goes immediately into the exhaust when the transfer port opens:

The rebound from the baffle cone pushes it all back, that's what makes the expansion chamber so effective.

 

[87Octane]

The rebound from the baffle cone pushes it all back, that's what makes the expansion chamber so effective.

No it does not because in reality (because of short circuiting) the exhaust has air-fuel it.....but he does not show that in the video.

(The part that is red (the exhaust) in reality has blue mixed in also....but the video doesn't show that.)

 

[Street Ryderz]

It explains wave effects, but not short circuiting.

Notice at this point in the video he does not mention that some intake flow goes immediately into the exhaust when the transfer port opens:

Wow man

No it does not because in reality (because of short circuiting) the exhaust has air-fuel it.....but he does not show that in the video.

(The part that is red (the exhaust) in reality has blue mixed in also....but the video doesn't show that.)

Your lost in confusion, Yes the reflected sonic wave pushes it back and if you payed attention he clearly stated where the wave aided the scavenging and there for prevented the short circuiting! And that was the point because only as the port and pipe timing are working together does this occur and at all other times the cylinder is left short circuited to varying percentages due to the total loss of that amount of charge! This is what I stated before and you obviously still don't understand all of this stuff so what ever dude!

 

[87Octane]

No it does not because in reality (because of short circuiting) the exhaust has air-fuel it.....but he does not show that in the video.

(The part that is red (the exhaust) in reality has blue mixed in also....but the video doesn't show that.)

Yes the reflected sonic wave pushes it back

If air-fuel (blue) is mixed in with part of the exhaust gas (red) (due to short circuiting. Not shown in the video but shown below) the reflected wave from the baffle cone is not going to be tuned to act on it. It is mostly exhaust and pushing it back in (even though it has air-fuel in it) would be bad.

P.S. You still don't understand what short circuiting is. It is not how you defined it in your current post or posts #108 forward.

It is not this (which you wrote in post #119 after I gave you the answer in post #118--> https://motoredbikes.com/threads/sm...onomy-and-emissions.58625/page-12#post-540256 ):

and at all other times the cylinder is left short circuited to varying percentages due to the total loss of that amount of charge!

or this (which you wrote in post #127 after I gave you a detailed explanation in post #122--> https://motoredbikes.com/threads/sm...onomy-and-emissions.58625/page-13#post-540267 ):

and as I said above or below this point where the cylinder is over filled it's left short circuited.

The paper linked below does a good job of explaining and illustrating what short circuiting is:

http://www.mhi.co.jp/technology/review/pdf/e383/e383151.pdf

Please read it!

 

[HumanPerson]

Will there be popcorn with the show?

 

[DAMIEN1307]

Will there be popcorn with the show?

NOPE...No popcorn...lol.

After showing my buddy/expert from the missile and aeronautics proving grounds at White Sands, this diatribe of drivel in this thread, He came to a similar conclusion that i did.

This "garden" of weeds, thorns and thistle will never go away as long as it has a source of "water and fertiliser" to continue to feed it.

Simply put, stop cultivating...Its already up to 13 pages...That is what i have decided to do as i believe this is sucking the life out of what we do here on the forum.

I will instead, choose to reply and help those who actually have a "dog in the fight", That is, an actual bike that needs to be built, worked on and improved, fixed etc. rather than waste time on someone who has no intention whatsoever to even acquire or build one of his own, let alone asking for any help or advice whatsoever...He already seems to "know it all".

His copy and paste pseudo-scientific BS that he himself does not even understand, doesnt lend itself to helping anyone here in the forums, except himself as he continues to feed his own self aggrandised ego, thus drawing us away from our purpose of being here in the first place.

If he is so smart, let him design an engine himself that will do all the things he is "carping" about.

This is my last missive on this topic...I for one, will no longer encourage this waste of fresh air and skin to proliferate any further...lol...DAMIEN

 

[87Octane]

His copy and paste pseudo-scientific BS that he himself does not even understand

The person who made that claim in this post---> https://motoredbikes.com/threads/sm...onomy-and-emissions.58625/page-11#post-540208

Doesn't even know how a 2 stroke engine works on the most basic level!

Proof is he thinks the intake and transfer port can be at the same level in the cylinder!---> https://motoredbikes.com/threads/sm...onomy-and-emissions.58625/page-10#post-539401 (Here is the evidence that was wrong --> https://motoredbikes.com/threads/sm...onomy-and-emissions.58625/page-10#post-539403 )

To even think that could be possible is unimaginable!

So how he is going understand part throttle? (Answer: He does not understand. He is just taking a totally blind stab at the information I provided.)