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 ?
The 710 is more comparable to the later models of GE's FDL engine (used in the C44 series locomotives in 16 cylinder form) than it is to the GEVO, which;as other posters have pointed out) is a larger displacement engine which runs at higher RPM's.
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
I though that 2 strokes of any kind (diesel, gas) run higher rpms than 4 strokes.
VGN Jess
The Crossley HST, a two stroke V-8 with exhaust pulse pressure charging, best known as the original engine for the Irish CIE Class A and the British Rail Metrovick Class 28, ran at 625 rpm. These were replaced by EMD 12-645E engines in the Irish locomotives. The big marine diesels from Sulzer and MAN B&W turn at about 120 rpm.
The MTU 4000 runs at 1800 rpm and other four strokes run at 2100 rpm.
It is more difficult to design a two stroke to run at a high rpm than a four stroke which of course has a full induction stroke to fill the cylinder.
M636C
Randy Stahl Most of the GEs run 150 RPM faster (1050 RPM) than the 900 RPM EMDs also. Randy-understood, but why wouldn't EMD set a WOT 1,050 RPM prime mover limit? I though that 2 strokes of any kind (diesel, gas) run higher rpms than 4 strokes. Randy
Most of the GEs run 150 RPM faster (1050 RPM) than the 900 RPM EMDs also.
Randy-understood, but why wouldn't EMD set a WOT 1,050 RPM prime mover limit? I though that 2 strokes of any kind (diesel, gas) run higher rpms than 4 strokes.
Randy
timz Thank you to all who responded; much appreciated. I guess all the answers lead me to another question: why has (did) EMD choose lesser cylinder displacements than GE so that whatever HP GE put out with any locomotive EMD could match it? It just seems to me that since the U36C, GE next version locomotives were always higher in HP than the prime movers EMD were putting on market at roughly the same time. Offhand guess: the 12-cyl GEVO has more displacement than the 16-cyl 710.
Thank you to all who responded; much appreciated. I guess all the answers lead me to another question: why has (did) EMD choose lesser cylinder displacements than GE so that whatever HP GE put out with any locomotive EMD could match it? It just seems to me that since the U36C, GE next version locomotives were always higher in HP than the prime movers EMD were putting on market at roughly the same time.
Offhand guess: the 12-cyl GEVO has more displacement than the 16-cyl 710.
At the time of its' creation, the 20-645 was a technological tour de force.
BTW, the current 16-710 can produce 4500-4600 hp into the generator.
CPM500
VGN JessGE gets more HP out of a 12 cylinder GEVO than EMD does with a 16 cylinder
VGN Jess Why has GE never had to build a 20 cylinder prime mover to achieve higher horespower, but EMD has had to build two (SD45 and SD80MAC) to do so? Even now, GE gets more HP out of a 12 cylinder GEVO than EMD does with a 16 cylinder 70ACe. What does GE know that EMD doesn't?
Why has GE never had to build a 20 cylinder prime mover to achieve higher horespower, but EMD has had to build two (SD45 and SD80MAC) to do so? Even now, GE gets more HP out of a 12 cylinder GEVO than EMD does with a 16 cylinder 70ACe. What does GE know that EMD doesn't?
Although GE never built a 20 cylinder version of the Cooper Bessemer derived FDL engine (the engine line used in their road locomotives until the advent of the HDL (used in the AC6000CW) and its evolved cousin the GEVO engine), they did build an 18 cylinder HDL test engine. this was supposed to be rated at around 7,000 HP (though I imagine it's North American locomotive rating would have been about 6,750 HP).
The new EMD 12 cylinder Tier IV compliant engine will probably have a rating of 4400-4500 HP in locomotive service so it will be comparable to the GEVO.
A lot has to do with cylinder bore, stroke, and RPM of the engine.
It isn't just a matter of the number of cylinders;
The 20 cylinder 710 is more powerful than the 16 cylinder FDL or the 12 cylinder GEVO, however.
The two sixteen cylinder engines, the GE HDL and the EMD 265H were both rated at the same 6000 HP. The experimental EMD 12-265H was the same power as the 12 cylinder GEVO. EMD chose for good reasons to sell the 16-710 instead, not least because that's what the customers wanted.
EMD have an experimental 12 cylinder four stroke engine and it is expected that this will develop 4500 HP.
In export locomotives, an Alco 12-251 developed 2000 HP and was a competitor with the 16-645E, and had the advantage of generally lower fuel consumption, but the EMD outsold the Alco (except in India, where the ALCO could be built locally).
It is true that the 20-645E3 was necessary to match the 3600 HP of the FDL16, but the GE engine was not more successful than the EMD. At the time many more 3000 HP locomotives were built than 3600 HP.
The 20-710G3 was more powerful than any GE engine of the time but only sold a few examples.
In general, EMD engines last longer than GE engines. In time the cast crankcase of the GE FDL cracks and requires replacement, after ten to twenty years depending on the duty cycle. EMD 645 engines have lasted more than 40 years and many are still in service. These older engines might not be as economical or emissions friendly, but they still work.
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