M636C carnej1 wrote the following post 6 hours ago: Wizlish carnej1 one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast. He probably means the Kockup 'Collins' class. These are Hedamora (Swedish) engines, and if I am not mistaken there were at least two types of locomotives that had their engines installed. I'd be interested to hear technical details of these engines (and the T45 locomotive). They may have had problems but nothing like the woes of the 338s! I admit I'm late to correct this out but I did not type the above comment, it was a quote from another poster included in one of my replies.. I would ask that people be careful when quoting to ensure that they are not inadvertently attaching my name to someone else's comment (I try to do likewise).. Thanks. Indeed the original quote was mine... In a recent post I correctly quoted you but the original poster's name disappeared from the "boxed" quote through no action of mine. I assumed that in that case, it was still clear that you posted the "outer" quote referring to the unidentified "inner" quote. All of this has come about because the changes to the forum show the text as displayed when quoting. Previously and on other fora, control codes were displayed that made it easer to ensure that everything was correctly attributed. In my case on this machine running IE 8, I have to cut and paste the whole quotation because the "quote" button doesn't work. But I for one do try to keep the poster's name in quotes, not always with success. M636C
Wizlish carnej1 one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast. He probably means the Kockup 'Collins' class. These are Hedamora (Swedish) engines, and if I am not mistaken there were at least two types of locomotives that had their engines installed. I'd be interested to hear technical details of these engines (and the T45 locomotive). They may have had problems but nothing like the woes of the 338s!
carnej1 one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast.
He probably means the Kockup 'Collins' class. These are Hedamora (Swedish) engines, and if I am not mistaken there were at least two types of locomotives that had their engines installed.
I'd be interested to hear technical details of these engines (and the T45 locomotive). They may have had problems but nothing like the woes of the 338s!
I admit I'm late to correct this out but I did not type the above comment, it was a quote from another poster included in one of my replies..
I would ask that people be careful when quoting to ensure that they are not inadvertently attaching my name to someone else's comment (I try to do likewise)..
Thanks.
No problem.
Ironically I posted my complaint on the same day that I quoted a poster on another thread on this forum without doing my due dilligence; his original post was from two years ago and thus was outdated information but had been a valid observation when he first posted it..
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
That's a great explanation; thank you. I will wonder no more. :)
VGN Jess TIMZ: Then why wouldn't EMD have used the GE displacement metrics and really had a powerful engine?
TIMZ: Then why wouldn't EMD have used the GE displacement metrics and really had a powerful engine?
carnej1 The U.S.Navy does not have any diesel submarines. The last one, Bonefish, had 3 Fairbanks engines
The U.S.Navy does not have any diesel submarines. The last one, Bonefish, had 3 Fairbanks engines
I think the more recent boats use CAT 3516 engines....
Certainly there is a shock qualified CAT 3516 available and we replaced the Detroit 16-149s in our FFG-7s with Cat 3516s. I'm told the crews like them and they reliably produce their rated power.
M636C
noemdfan Nope. 664 Cubic Inches per cylinder.
Nope. 664 Cubic Inches per cylinder.
He probably means the Kockums 'Collins' class. These are Hedemora (Swedish) engines, and if I am not mistaken there were at least two types of locomotives that had their engines installed.
carnej1one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast.
tdmidget M636C Erik, The 24 cylinder Winton may have been intended for surface vessels, but surface ships tended to have multiple engines, and a large single engine would not be as great an advantage as in a submarine which effectively needed to have two main engines simply from space considerations, at least with WWII submarine hull designs. With current designs based on the USS Albacore, the teardrop shaped hull is shorter and beamier and one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast. M636C The U.S.Navy does not have any diesel submarines. The last one, Bonefish, had 3 Fairbanks engines.
M636C Erik, The 24 cylinder Winton may have been intended for surface vessels, but surface ships tended to have multiple engines, and a large single engine would not be as great an advantage as in a submarine which effectively needed to have two main engines simply from space considerations, at least with WWII submarine hull designs. With current designs based on the USS Albacore, the teardrop shaped hull is shorter and beamier and one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast. M636C
Erik,
The 24 cylinder Winton may have been intended for surface vessels, but surface ships tended to have multiple engines, and a large single engine would not be as great an advantage as in a submarine which effectively needed to have two main engines simply from space considerations, at least with WWII submarine hull designs.
With current designs based on the USS Albacore, the teardrop shaped hull is shorter and beamier and one submarine class I am very familiar with has three 90 degree V-18 engines arranged abreast.
The U.S.Navy does not have any diesel submarines. The last one, Bonefish, had 3 Fairbanks engines.
That's true but FM opposed piston engines were the standard auxilary power for U.S Nuclear submarines up until quite recently and the older boats still have them installed..
Indeed, but I'm not in the US Navy....
D NICHOLS GM Diesel also built some 16V71 engines with one piece crankshafts. They soon found out what a mistake that was. Cranks broke at the point of where the two 8V71 blocks were joined. They corrected that by going with a bolted two piece crank. Detroit Diesel also built some 24 cylinder engines. Far as I know, none of those had a one piece crank.
GM Diesel also built some 16V71 engines with one piece crankshafts. They soon found out what a mistake that was. Cranks broke at the point of where the two 8V71 blocks were joined. They corrected that by going with a bolted two piece crank. Detroit Diesel also built some 24 cylinder engines. Far as I know, none of those had a one piece crank.
My dad worked on a 24 cylinder GM diesel while attending the USN's Diesel Engineering school at Cornell, late 1944 early 1945. He was emphatic that it was a one piece cank as they had to replace a broken one at great expense.
Paul of Covington Deggesty owlsroost CPM500 The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO. Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL. General question - since the two engines have similar displacements, but the 710 has twice as many power strokes (at the same RPM) as the GEVO, why isn't the 710 considerably more powerful ? Presumably the effective stroke length of a two-stroke diesel is less than on a four-stroke, due to the ports in the cylinder wall being uncovered for part of the stroke ? I have always understood that every other stroke (movement of the piston) in a two-stroke engine is a power stroke, whereas every fourth stroke in a four stroke engine is a power stroke. Therefore, at the same rpm, a two-stroke engine has twice the power strokes that a four-stroke engine has. I'm no expert, but I remember reading that because of restricted breathing (the cylinder must be purged and re-charged at the bottom part of each stroke) the 2-stroke can't produce anywhere near double the power of the 4-stroke. I'm sure others on this forum can tell us more.
Deggesty owlsroost CPM500 The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO. Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL. General question - since the two engines have similar displacements, but the 710 has twice as many power strokes (at the same RPM) as the GEVO, why isn't the 710 considerably more powerful ? Presumably the effective stroke length of a two-stroke diesel is less than on a four-stroke, due to the ports in the cylinder wall being uncovered for part of the stroke ? I have always understood that every other stroke (movement of the piston) in a two-stroke engine is a power stroke, whereas every fourth stroke in a four stroke engine is a power stroke. Therefore, at the same rpm, a two-stroke engine has twice the power strokes that a four-stroke engine has.
owlsroost CPM500 The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO. Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL. General question - since the two engines have similar displacements, but the 710 has twice as many power strokes (at the same RPM) as the GEVO, why isn't the 710 considerably more powerful ? Presumably the effective stroke length of a two-stroke diesel is less than on a four-stroke, due to the ports in the cylinder wall being uncovered for part of the stroke ?
CPM500 The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO. Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL.
The 710 displaces 11.6 litres/cyl vs 15.67 for the GEVO. Doing the math reveals that the total displacement of the EMD is 185.6 litres vs. 188 litres for the GEVO.
Stated design criteria for the GEVO indicates that the 12 cyl was designed for the same output as a 16 cyl. FDL.
General question - since the two engines have similar displacements, but the 710 has twice as many power strokes (at the same RPM) as the GEVO, why isn't the 710 considerably more powerful ?
Presumably the effective stroke length of a two-stroke diesel is less than on a four-stroke, due to the ports in the cylinder wall being uncovered for part of the stroke ?
I have always understood that every other stroke (movement of the piston) in a two-stroke engine is a power stroke, whereas every fourth stroke in a four stroke engine is a power stroke. Therefore, at the same rpm, a two-stroke engine has twice the power strokes that a four-stroke engine has.
I'm no expert, but I remember reading that because of restricted breathing (the cylinder must be purged and re-charged at the bottom part of each stroke) the 2-stroke can't produce anywhere near double the power of the 4-stroke. I'm sure others on this forum can tell us more.
DKW built a lot of 2-stroke gasoline engines. One of their markings on some of their models were 3=6 pointing at their thinking you could get twice the HP. A little 3 cylinder 750cc DKW engine put out 34 HP.
The recent posts have thouroughly addressed my initial query; thank you very much. The answers have shown me that intuitive thinking is not always relevant in the railroad power industry. While a railroad supporter, I am ignorant of these kinds of technical issues for never having worked on a railroad (though my grandfather was an engineer on the Virginian RR for 35 years). Merry Christmas to all who helped me understand how complex something I thought was relatively simple!!!
Partial answer to #1 has already been discussed. 2-cycle has more power strokes per unit time, so higher HP; 4-cycle is more efficient (and can use higher peak and mean pressure over a longer stroke) so greater unit power for a given displacement. Then you factor in the injection characteristics, the permissible machine speeds, etc.
M636C can probably provide actual numbers for various kinds of EMD 567/645/710 vs. GE and Alco 4-cycle service engines. If we ask him politely, he might work them up if not already available...
#2 -- the rotational speed is determined by a number of factors, ranging from how the engine is balanced net of power thrust on the pistons (which changes during the stroke) to how the firing order, etc. puts torsional strain on the crank. EMD engines were classically designed for the 900 rpm range, and running them even 25 to 50 rpm faster can significantly degrade reliability and engine life. GEs are, in my opinion, being overdriven at 1050 rpm, but I'm not in the industry and don't have reliability data -- under Welch, GE developed the power-by-the-hour guarantee system to cope with the real-world effects of diminished reliability at higher rotational speed.
What difference is there between the hp per cc displacement of an EMD 2 cycle engine and a GE 4 cycle engine?
Does a 2 cycle engine run slower than a 4 cycle engine?
Johnny
VGN JessWouldn't 16 cylinders burn more fuel than 12?
You're asking the wrong question. My father had a 12-cylinder E38 BMW that was good for over 28 mpg indicated at just over 80 mph, on a road that was far from flat. I have never seen an eight-cylinder model of the same car that would get even remotely similar mileage under the same conditions -- from less displacement.
There is a bit more loss, thermodynamic and mechanical, out of more cylinders, and of course the capital cost of more injectors, bearings, valves, etc. is higher. So there are advantages to building engines with fewer cylinders... if you haven't already costed-down much of your production cost, established a cadre of skilled maintenance people, developed a robust aftermarket for parts and supplies, etc. for an engine design with more cylinders.
The point is not just how many cylinders an engine has. I think most Class I railroads care more about ton-miles and over-the-road reliability (including the ability to work partially disabled without catching fire!) than about pure specific fuel consumption in the prime mover.
There are certainly cases where fuel economy is significant -- that's part of the appeal of older Alcos in shortline service, I believe. But that's normally a fairly small part of the overall cost of assuring motive power. Again, it's working reliability that matters, and railroads have (or ought to have) a pretty good idea of how the balance between fewer cylinders and easier maintenance, etc., works out economically.
Now, what the locomotive manufacturers say to the railroads when trying to sell their products is another matter. One that I suspect requires other criteria than straight factual truth to evaluate...
VGN Jess Best answer yet; thanks! Generally, I was primarily considering the 1965 period on, and should have been more specific in my query. Specifically, I just couldn't (can't) understand why EMD would use a 16 cylinder 2 stroke (SD70ACe) with less HP than a GE 4 stroke (ES44AC) w/only 12 cylinders and why customers would buy it (16)? Wouldn't 16 cylinders burn more fuel than 12?
Best answer yet; thanks! Generally, I was primarily considering the 1965 period on, and should have been more specific in my query. Specifically, I just couldn't (can't) understand why EMD would use a 16 cylinder 2 stroke (SD70ACe) with less HP than a GE 4 stroke (ES44AC) w/only 12 cylinders and why customers would buy it (16)? Wouldn't 16 cylinders burn more fuel than 12?
It does not burn more fuel. It burns the same amount of fuel and the engine has been around longer. Everyone knows how to work on it.
VGN Jess In looking back over time, GE has always produced a prime mover w/more HP, during the same time period, than EMD. Why is EMD always seemingly behind GE in the HP "game"?.
In looking back over time, GE has always produced a prime mover w/more HP, during the same time period, than EMD. Why is EMD always seemingly behind GE in the HP "game"?.
GE only entered the market around 1960 with the U25.
At that time EMD produced the SD24 with the same number of cylinders but 100 HP less.
Apart from the SD45 and SD45-2 with 20 cylinders, to match the U36C, EMD and GE had matching engines, the 12-645E3 in the GP39 matchng the FDL-12 in the U23B and the 16-645E3 in the SD40 matching the FDL-16 in the U30C. So apart from the most powerful locomotives in the range (which were not the most popular) EMD and GE had matching engines.
Later with the 710 engine, the 12-710G3 in the GP59 matched the increased power of the FDL-12 in the B30-7A and later the 16-710 at 950 rpm in the SD75 was only 80HP less than the FDL-16 in the Dash9-44CW.
In the 6000 HP locomotives, the 16-265H matched the HDL-16.
It is only with the current GEVO-12 compared to the 16-710 that there has been a consistent period where GE has had a locomotive with fewer cylinders. EMD could have built the SD89MAC but customers asked for the the SD70ACe instead.
The EMD 16-710 engine pretty much matches the fuel consumption of the GEVO-12. The EMD engines are kbnown to last much longer than the GE FDL engines. Most of the Dash 8s rebuilt recently have new engines, while most rebuilt EMD locomotives retain their original engine, rebuilt with new power assemblies. In the long term, the EMD is cheaper to own.
To be fair, the GEVO is yet to establish whether it will last as long as an an EMD two stroke.
As from now, it appears that EMD and GE will again have equivalent engines with the same number of cylinders, with the new EMD four stroke engine against whatever GE are going to call their Tier 4 engine, with both producing 4500HP.
So there have been specific periods where GE had engines that were more powerful per cylinder, but this has not been consistent. In general EMD and GE have had matching engines with the same number of cylinders.
Thanks; I understand that (conservatism) as a probable reason.
Generally, conservatism. This is what gives EMD its reputation for reliability and longevity. There are some exceptions, but EMD was hesitant to push the limits of their design, because it had the potential to create problems. Look at the SD50, for example. Railroads tend to value reliability just as much as horsepower. GE caught up with the -8s and -9s in terms of reliability and longevity.
Thank you to all who responded to my questions; I learned much. That said, I still don't feel the crux of my query was answered. I was asking for opinions (hopefully from EMD/GE experts), why would EMD use two stroke engines at 900-950 max RPMs (over 4 strokes at 1,050 RPMs), when GE gets more HP from using (in some cases) 4 less cylinders? It just seems to me, in looking back over time, GE has always produced a prime mover w/more HP, during the same time period, than EMD. Why is EMD always seemingly behind GE in the HP "game"? Just curious. If someone thinks they already answered that, I apologize for not recognizing it. Merry Christmas to all! :)
Randy Vos
"Ever have one of those days where you couldn't hit the ground with your hat??" - Waylon Jennings
"May the Lord take a liking to you and blow you up, real good" - SCTV
IN THE 70s WE PURCHACED A CLEVELAND 16 278a. FROM THE NAVY AT ANAPOLIS MD. WAS A EXPEREMENTAL ENGINE WITH A 12 CYL. ROOTS BLOWER & A LARGE ELECTRIC BLOWER ON THE FLOOR ABOVE. WE PURCHACED IT & PUT A 16 CYL BLOWER BACK. IT RAN IN A DREDGE FOR MANY YEARS AFTER. NOT MANY LEFT TODAY. BUT THATS 70 YEARS AGO. HERBYGD@AOL.COM
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