Subject:
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Re: BNSF new paint
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Newsgroups:
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lugnet.trains
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Date:
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Wed, 26 Jan 2005 22:04:51 GMT
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Viewed:
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3160 times
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In lugnet.trains, Derek Raycraft wrote:
> In lugnet.trains, Larry Pieniazek wrote:
> > Well now I'll display MY ignorance... I know that a lot of 2 cycle engines are
> > valveless but I did not think it was mandatory that they not have exhaust
> > valves.
>
> They are probibly a lot more efficent when whey do have exhaust vales. A basic
> two stroke doesn't clear the cylinder of exhaust very efficiently. By opening
> the top of the cylinder through exhaust valves the rush of intake air will
> definitly clear the cylinder more effectively.
Oh ya, no doubt.
I think one of the reasons for this whacky two piston, one cylinder, central
combustion chamber arrangement is that in an exhaust port system, with the
proper amount of lag between cylinders, you can arrange the exhaust to happen at
a moment when there is a lot of compression in the cylinder giving a nice
blast... Not sure, would have to study that Deltic animation or whatever to be
sure.
> However in the two cylinder one combustion chamber arrangment you can't have
> cylinder head mounted valves, because there isn't a cylinder head. This is why
> I'd be surprised if there were 2 stroke with exhaust values, or 4 stroke
> versions of this engine design.
Nod. BUT it can't be a completely uniform cylinder wall, there have to be at
least some cutouts for the fuel injectors. The FM pistons have S shaped
depressions for fuel injector (spray paths?) stuff.
So arguably if you had good valve timing you could have valves with curved
bottom surfaces that fit into the cylinder sidewalls, or some sort of ported
arrangment.
> If there were I be all freaked out by the concept all over again.
The very notion of a diesel is freaky if you ask me. Where's the spark! hehe.
> > Anyway, I am pretty sure the FM is 2 cycle, I think the Alco 244 was (but too
> > lazy to go look),
Got less lazy. http://www.sdrm.org/roster/diesel/alco/ It's a 4 cycle, if that
scan of the operation manual is for real
> > and the GM/EMD 567, 645 and 710 (so named because that's their
> > displacement in cubic inches... *per cylinder*!! at least IIRC) engines are also
> > 2 cycle. GM/EMD has switched to 4 cycle in their latest stuff though.... Here's
> > a link:
> >
> > http://www.gmemd.com/en/pmi/diesel_engines/
> >
> > (the 645 and 710 are 2 cycle, but have 4 exhaust valves per cylinder... no
> > Intake of course since they're fuel injected Diesel, but these are not OP,
> > they're conventional single piston per cylinder)
> >
> > This level of detail is hard to even *suggest* at the scale we work at though.
> > I managed to work something in that looks like a fuel rail on my latest project
> > but I did nothing at ALL to suggest exhaust stuff...
>
> I was thinking more of doing it in Technic and seeing if I could get the
> cylinders to face off like the Deltic Engine.
>
> Thanks for all the info on this. It's really interesting stuff.
NP. But I'm realising I didn't do enough research before and some of my details
are off. :-)
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Message has 1 Reply:
 | | Re: BNSF new paint
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| (...) Snip (...) Atually, from what I remember of the movies we watched @ school, the air exchange can run up to about 98% clean air in a loop type arrangement. That's using something like 200% excess air in order to clear the cylinder of combustion (...) (20 years ago, 27-Jan-05, to lugnet.trains)
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Message is in Reply To:
| | Re: BNSF new paint
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| (...) They are probibly a lot more efficent when whey do have exhaust vales. A basic two stroke doesn't clear the cylinder of exhaust very efficiently. By opening the top of the cylinder through exhaust valves the rush of intake air will definitly (...) (20 years ago, 26-Jan-05, to lugnet.trains)
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