How dirty is a CONSTANT RPM 2-stroke with a Tune-Pipe?

[Andyman]

Originally Posted by Logic

I'm going to pretend we actually read each others posts with the intent to understand,
rather than immediately rushing to engage in some insane game of intellectual one-upmanship to satisfy a need to be considered cleverest and for the pure joy of a good argument.

ie: This reply is not actually for aerohead, as he wont read it with the intent to understand it, but for others reading this thread.

...

Leaving the placement of the catalyst after the tune-pipe and centrifuge as the last remaining problem to be solved before light and simple, fixed rpm 2-strokes might be unbanned.

Any ideas?
One does not want to waste fuel to re heat a damn catalyst..?

I'm not sure that Aerohead disapproved of this subject. I think his point was that the legal requirements could be difficult to satisfy for new two stroke engine products in the US. I thought that the information he gave us was useful. If a new two stoke engine could meet the emission requirements it may be accepted. With the recent changes at the EPA, that might be easier. I hope we are not going to be breathing more pollution soon, but we probably will because of the large amount of fuel being used or burned up in wars. If we can clean up old two stroke engines, it would be a step in the right direction.

I do have an idea. I suggest wrapping the expansion chamber (tune-pipe) in insulation so the exhaust gas will be hot enough for the catalyst. The centrifuge may not be needed if the two stroke oil burns cleanly. I think it would be useful to add valves to the transfer and exhaust ports. They could be rotory valves so they can operate quickly. That could improve engine efficiency by delaying the opening of the exhaust port. The transfer port opening could also be delayed until after the piston reaches the bottom of the stroke to allow enough time for most of the exhaust to leave the cylinder before the new fuel mixture starts to go in. This might work better if a reed valve is added to the bottom of the transfer port and the volume of the transfer port is increased.

[Logic]

Originally Posted by Andyman

I'm not sure that Aerohead disapproved of this subject. I think his point was that the legal requirements could be difficult to satisfy for new two stroke engine products in the US. I thought that the information he gave us was useful. If a new two stoke engine could meet the emission requirements it may be accepted. With the recent changes at the EPA, that might be easier. I hope we are not going to be breathing more pollution soon. If we can clean up old two stroke engines, it would be a step in the right direction.

I do have an idea. I suggest wrapping the expansion chamber (tune-pipe) in insulation so the exhaust gas will be hot enough for the catalyst. The centrifuge may not be needed if the two stroke oil burns cleanly. I think it would be useful to add valves to the transfer and exhaust ports. They could be rotory valves so they can operate quickly. That could improve engine efficiency by delaying the opening of the exhaust port. The transfer port opening could also be delayed until after the piston reaches the bottom of the stroke to allow enough time for most of the exhaust to leave the cylinder before the new fuel mixture starts to go in. This might work better if a reed valve is added to the bottom of the transfer port and the volume of the transfer port is increased.

People make the mistake of liking to think that electricity, EVs and even 4-Strokes are clean Andyman. They are not:


https://en.wikipedia.org/wiki/World_...nd_consumption

Wind blows.
We all of us, anywhere, breath in an air molecule that's been in for eg: Marilyn Monroe's lungs, once every 30 years IIRC.
And she exhaled what? A millionth of what a car or power plant does in a day!?

Then consider that city driving, which is 98% of all driving worldwide means accelerating WEIGHT from robot to robot etc, and that, that accounts for 68% of fuel used!
(vs 14% for aero)

So ye; the lighter we can make vehicles...
and 2-strokes win here, as far as available engines go.
(Better would be Linear Generators, but that's not going anywhere fast atm)

The other thing to consider is that this clean 2-stroke is a ~250cc CONSTANT rpm engine to replace the average load of around 20kw of a normal, variable rpm engine, in a series hybrid.
This lowers the expensive, weighty battery requirements dramatically and makes optimizing the engine (of any sort) far-far cheaper and simpler.

ie: There is no need for fancy, expensive valves and direct injection etc, that clean up the emissions from a variable rpm engine:
The ports (and tune pipe etc) can all be optimized to open at the optimal/desired crank angle/rpm... easily and cheaply!

I LIKE the wrapped tune pipe idea though! Thx!
If it's designed fort the extra volume; that's good thinking (of a simple solution!) and can be extended to any centrifuge too, for very little in extra weight.

[cRiPpLe_rOoStEr]

Originally Posted by Andyman

If a new two stoke engine could meet the emission requirements it may be accepted. With the recent changes at the EPA, that might be easier.

In fact it is possible to make an emissions-compliant 2-stroke engine, yet it would be harder to justify from a marketing standpoint after some countries effectively banned the imports of new 2-stroke motorcycles around 2008, and some of those countries in fact have a larger motorcycle market than the United States. Not to mention the latest successful 2-stroke engines became more concentrated around lower displacement brackets.