I have often wondered why EMD never produced a supercharged only version of the 710 engine. Just on a displacement basis you would expect a 10% power increase which would be useful. I can see the simplicity making a MP1650 or 2200hp GP58 sellable, at least till the emission laws tightened. Pretty certain you need a turbo now to have a hope of passing.
Any thoughts on this?
I think you mean a blower version of the 710. As I remember it EMD continued to produce both versions of the 645 after the introduction of the 710 forlocomotives. There are kits available to bring these older engines up to tier 2 standards if your so inclined and the grateful taxpayers of California will cover most of the cost for you.
creepycrank I think you mean a blower version of the 710.
I think you mean a blower version of the 710.
You are correct. I changed it from turbo to supercharged, AKA "Blower".
Still don't know why there wasn't a blower 710...
LensCapOnI have often wondered why EMD never produced a supercharged only version of the 710 engine.
The more correct term is "Roots-blown" - the GM two-stroke architecture requires positive charge-air pressurization and fairly high mass flow for scavenging, and the Roots design is a positive-displacement blower.
As I recall there has been some discussion over adapting simple scavenging to a 710 engine. The single greatest reason is giant-sucking-sound fuel efficiency: why bother with 710-size stroke and power assemblies when 645s do everything a lower-efficiency Roots-blown engine can do with less fixed displacement and better-costed-down aftermrket support. To my knowledge the smallest domestic 710 is a 12-cylinder block, which still has opportunity value in larger road engines (where it would very lkely be turbocharged)
There are also serious concerns about emissions from a Roots-blown engine; these would be greater for a 710 even if the injection and other instrumentation were jiggered to make the engine run across its 'new' powerband with correct valve timing for the scavenging.
Much of the reason for removing the EMD turbo in the past had to do with the size and complexity of older GM units, which essentially spun a non-positive-displacement compressor via an overrunning sprag-clutch-like drive to produce adequate charge air at lower crankshaft rpm and low relative exhaust mass flow, then operated as a full exhaust-energy turbocharger at higher sustained output. When that solution was devised, turbochargers were still rare and expensive things; UP for one experimented with multiple turbos feeding groups of cylinders, but any such approach was more difficult to implement than EMD's. Nowadays the production of turbochargers, and knowledge of the ways to run and maintain them, is widespread (and, in general, straight turbocharging with multiple smaller units is the preferred method for any new engine architecture) so there is little point in trying to adapt Roots drive to get crappier performance all around.
Complicating this is the relative lack of 'small' locomotives with 710s. It remains to be seen if there is a market for radial-trucked 'lower-power' locomotives when the current generations of deturboed SD40s and the like have reached their relative ends of life; there have certainly been discussions about adapting radial trucks to 'older' locomotives but no one has yet found the 'operation' worthwhile (vs. just buying older HTCR-trucked engines with turbo 710s) -- this was for example a perceived 'alternative' for the Alaska Railroad in the thread here on the "GP69" that Might Have Been...
Overmod To my knowledge the smallest domestic 710 is a 12-cylinder block, which still has opportunity value in larger road engines (where it would very lkely be turbocharged)
To my knowledge the smallest domestic 710 is a 12-cylinder block, which still has opportunity value in larger road engines (where it would very lkely be turbocharged)
Don't forget the ~2000 HP 8-710 used in the ECO rebuild program (you may have remembered and edited your post by the time I finish writing this).
The gear-driven roots blowers place quite a load on the engine, and I have heard from unofficial sources that the blowers necessary to supply an engine more powerful than about 2000 HP would start getting large enough to present a space problem in a locomotive setting.
The early EMD turbocharged 567 engines (as used in the GP20, SD24 and GP30) only provided at most a 600 HP increase in power. Once these locomotives cascaded down into switching service that minimal extra HP was no longer very beneficial, and the extra expense of maintaining what even by then was a outdated and non standard turbo design could not be justified on most railroads.
The 2500 HP 35 series units had a whole host of problems related to squeezing that much power out of the 16-567, and trying to process it through a 100% DC electrical system.
If a customer had really, really, really wanted one I'm sure that EMD could and would have produced a roots-blown 710. But, as was noted in the Alaska GP69 thread, any such inquiry would probably have been met with a very high price quote and direction from the EMD salesman toward the still-in-production and proven roots-blown 645 engine, or a turbocharged 8 or 12-710 of equivalent horsepower.
Greetings from Alberta
-an Articulate Malcontent
Fuel economy. The blower engines are just horrible in the upper notches.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Here's a 12-710 running without any exhaust boost into the turbo:
https://www.youtube.com/watch?v=9gjV7WpoyLs
Thanks for being considerate ... but I actually forgot about the 8-710 in the ECO package. The 8-645 was trouble enough...
SD70DudeHere's a 12-710 running without any exhaust boost into the turbo: https://www.youtube.com/watch?v=9gjV7WpoyLs
It's the twin-6-stack VO from Hell!
... interesting the noise the gear drive makes when it doesn't get overrun. Almost reminiscent of an Italian car...
I dimly remember discussions about using a better version of a positive-displacement blower. perhaps a Lysholm screw compressor, to provide the proportional scavenge air. They don't seem to have gone anywhere, but if some desire to provide higher-power-range nonturbo operation develops, that might be a better approach than driving a typical turbocharger-wheel arrangement mechanically as cheap default.
Since we're on the topic of lower horsepower applications of the EMD engines, was there ever any consideration of a 6-710?
And how many 6-645 engines were produced? Were they used in any other locomotives besides those Australian switchers?
SD70DudeSince we're on the topic of lower horsepower applications of the EMD engines, was there ever any consideration of a 6-710?
This reminds me a little of what my old girlfriend told me to ask to shut up Texans who kept boasting about 'everything's bigger in Texas'. She said to ask them if it was true that Texas had the largest midgets.
A midget engine with 710ci per cylinder out of a longer stroke might make sense if you needed or wanted parts commonalty with larger engines in a fleet. It certainly seems the thing would be easier to balance than an 8-710, so the issue comes down to why develop an inherently proportionally-smaller-than-8-cylinder-710-Roots-blown V6 instead of ... well, a 6-645 conversion of a 6-567, if you wanted a little more oomph and somewht easier parts availability.
There were a total of 80 G6Bs in Australia.
Of these only the last 25 had the 6-645E engine. I assume that there were at least a couple of spare engines. The Victorian Railways happily interchanged 567 and 645 engines in the eight cylinder locomotives and probably did so in the G6Bs.
The Victorian G6Bs, of which there were 75, were an exercise in keeping capital expenditure to an absolute minimum. The trucks were from old electric commuter cars. The trucks were one piece castings and about ten years old at the time they were fitted to the G6Bs, but the commuter cars were up to fifty years old, as were the GE traction motors that came with the trucks. A few of these locomotives are still running more than fifty years later themselves so some of the motors must be approaching 100 years old.
Five units built for Western Australia had Flexicoil trucks and D29 motors and these have lasted very well, with four still in service.
The 8-645E3 had equivalent engines driving mining trucks but the 6-567 and 6-645 were relatively big for their power output and Detroit 12-149 engines could provide the same power in a lighter and more compact package.
The 6-567 was a replacement for the 8-201A,which had been popular in the late 1930s but small switchers were less popular from then on.
In Victoria, train loads were smaller, and the G6Bs were able to work trains on branch lines where grain traffic was the main (and seasonal) work.
Peter
M636C The 6-567 was a replacement for the 8-201A,which had been popular in the late 1930s but small switchers were less popular from then on.
Ah yes, the SW-1 where SW stood for Six hundred hp Welded frame. A happy coincidence that it was also the first two letters of switcher.
All EMD diesels have vibration balance weights at each end of the camshafts . The shorter the engine the bigger the weights until you get to the 8-645 size. These were so heavy that they could break out a section of the endsheet just as ifmy dog Lucy bit it off. Thiscaused some scrambling in EMD to design a fix and it usually required welder from LaGrange to come out a do the repair. I never saw a 6- 645 probably because of this problem. If there was one they would sold those to the Coast Guard instead of de-rated 8-
Overmod SD70Dude Since we're on the topic of lower horsepower applications of the EMD engines, was there ever any consideration of a 6-710? This reminds me a little of what my old girlfriend told me to ask to shut up Texans who kept boasting about 'everything's bigger in Texas'. She said to ask them if it was true that Texas had the largest midgets. A midget engine with 710ci per cylinder out of a longer stroke might make sense if you needed or wanted parts commonalty with larger engines in a fleet. It certainly seems the thing would be easier to balance than an 8-710, so the issue comes down to why develop an inherently proportionally-smaller-than-8-cylinder-710-Roots-blown V6 instead of ... well, a 6-645 conversion of a 6-567, if you wanted a little more oomph and somewht easier parts availability.
SD70Dude Since we're on the topic of lower horsepower applications of the EMD engines, was there ever any consideration of a 6-710?
The only real reason for a 6-645 nowadays would be to allow use of 645 power assemblies without uprating the engine power over what the 'equivalent' 567 engine crankcase could sustain -- as such, the rotating 'inertial' counterbalance masses for the larger pistons were the critical requirement. Personally I wouldn't have thought the detail design of the weights needed to balance replace 567 piston assemblies with 645 equivalents in a V6 would have been that bad, but I know far less than creepycrank about the detail design of 567 engines, or how to lengthen the endcase dimensions or use 'denser' masses (depleted uranium anyone? ) to make the expedient conversion possible.
Now, harmonic balance damping is a different thing on a diesel engine -- in fact I thought it as torsional rather than inertial. Is that driven off the cam drive on a 6-567? I could certainly see scaling problems if it were...
The only reason for a 6-645 would be to allow use of 645 power assemblies without uprating the engine power over what the 'equivalent' 567 engine crankcase could sustain
The Victorian locomotives with 6-645E engines were rated at 750HP, while the 6-567C units were the familiar 600HP. I guess a margin of 150HP was within the design limits. They didn't issue separate load tables for the last 25 units.
M636CThe Victorian locomotives with 6-645E engines were rated at 750HP, while the 6-567C units were the familiar 600HP.
Revised my post accordingly. Presumably the locomotives for VR had improved crankcase construction from the factory, as would any American 6-cylinder switchers built with 645 power assemblies.
It is possible, perhaps even likely, that some of the folks doing the 567-to-645 conversion have not fully resisted the temptation to crank up the fuel rack a little to take advantage of their new 'higher displacement' -- and it's at least theoretically technically plausible that an added 150hp might not cause even long-term damage to the structure or components of a 567 case even of relatively early vintage. I'll leave that up to the EMD engine specialists on here to discuss.
Where do you get the idea that their ever was a 6-645 ? According to my No' 302 replacement catalog, PL B28 page 9 there is no such size engine.
creepycrankWhere do you get the idea that there ever was a 6-645 ?
M636C says it was an export engine, used on Victorian Railways in southern Australia. Are export-only products in the catalog you're citing?
To my knowledge, no United States railroad had an interest in new 6-cylinder power built with 645 power assemblies by the time the 645 engine was introduced. It is somewhat hard to imagine why railroad, even a Class 2, would -- given that the 567 would still be 'in being' as an engine option or parts support at that time.
My interest would be entirely in small or 'heritage' organizations wanting to convert an operating 6-567 to use 645 power assemblies, a known approach to getting longer life at minimum cost out of older locomotives. Several people have posed at length on the technical requirements to do that on larger engines; recently a couple of possible limits on the feasibility of doing a comparable swap on the very short V6 engine have been raised. While it would certainly be interesting to see the details of a factory 645 -- and how it solved the indicated balance-mass issues, which was evidently the case in Australia if they got any particular life out of them at 750hp -- the issues do remain on how well, indeed 'whether', a cost-effective 645-power-assembly conversion on a 6-567 could be made.
My 302 catalog says " Power Generation and Marine Propulsion" which includes all export types. I know it doesn't include Navy high shock engines (16 cylinder). Once again I would like tosee some sort of proof.
Just look up the Y class of Clyde power on Victorian Railways. Not particularly obscure and you should find adequate proof to satisfy your doubts on the existence of the 6-645E.
creepycrank My 302 catalog says " Power Generation and Marine Propulsion" which includes all export types. I know it doesn't include Navy high shock engines (16 cylinder). Once again I would like tosee some sort of proof.
Will this do?
http://www.victorianrailways.net/motive%20power/diagrams/ydia03.html
The official diagram which is usually correct.
That's an amazing site and this should amuse many...
http://www.victorianrailways.net/motive%20power/mckeen/mckeen.html
Notice the modifications to allow buffers and screw couplers.
The only known mistake on the site is the caption to the last photo in the McKeen section. The station is Culcairn, not Marulan and it's my mistake.
Some further thoughts...
The engines in the USA that might be being preserved are most likely early 567 engines. The usual sources suggest that there were 661 SW-1s fitted with 567 or 567A engines. The only other domestic units with 6-567s were 16 SW-600s which had 567C engines and these were almost exclusively industrial units rather than being operated by railroads. Hence my earlier comment about lack of interest in small switchers post WWII.
On the other hand the engines in Australia were 55 6-567Cs and 25 6-645Es.
I think most people talking about preserving 6-567s ignore the 6-567C because they are probably close to extinct in the USA.
I would suggest that any 6-567C could be easily converted to 6-645E provided the crankshaft counterweights can be fitted.
It might be easier to try to fit an 8-645E in place of the early 6-567 or 6-567A if the locomotive has the room for a slightly longer engine, even if the compressor has to be relocated.
I understand that Wabtec actually rebuilt 20-645E3s as 16-645E3Bs by cutting and shutting at both ends, but that relied on being able to get new or reconditioned crankshafts at a reasonable price.
You could probably cut an 8-645 or 12-645 down to make a 6-645 but you'd have to pay for a new crankshaft made from scratch.
There were a few rigid six wheel G6s, all with 6-567C engines, most in Lebanon I believe. That's not somewhere I'd go looking for old locomotives even if any were thought to survive.
While they barely existed with the small production run and there have probably been some recent losses, when I went looking about five years ago I was able to find then recent pictures of almost all 15 or so SW600's. A few had shabby paint, but all appeared to have been serviceable or had recently been operationable.
I suspect they've been desirable for industrial customers with the C block and the maintenance and fuel efficency advantages of 6 cylinders for light duty jobs, and still have a decent survival rate in 2020. Especially if 645 power assemblies can be installed for improved parts availability.
Reading through the reasons seem to be:
1) The required Blower would be so physically large that extra room would be required for it. Likely requiring a larger carbody for all units in the line.
2) The fuel use at full throttle was more than the market would accept once turbos were perfected.
Then the thread drifted in a fun way about six cylinder 645-710's. Well done there!
LensCapOn1) The required Blower would be so physically large that extra room would be required for it. Likely requiring a larger carbody for all units in the line.
I think not so much that the blower case dimensions are "too large to fit" than that they'd have to be different from corresponding 645 size, with all the costs associated with that.
Roots blowers are positive displacement, and are sized proportional to required scavenge-air flow, without wastegating for 'higher' flow than required as compressor-wheel turbochargers are. Now, the flow can be modified in at least two ways: increasing the case dimensions (and presumably some of the plenum dimensions to match) or by changing the drive gearing to spin the rotors faster. Keep in mind that the rotors themselves are already kept synchronized not by mutual contact but by substantial and fairly precise gears, and driving them faster will increase what is already high parasitic drag. Whereas increasing the case and other components "just" for a specialty 710 is going to be expen$ive both to design/produce initially and then stock parts for and support.
There is another 'potential' solution (in addition to using a different positive-displacement blower like a Lysholm) which is to beef up the existing EMD mechanical low-speed turbo drive so it can support adequate centrifugal plowing with relief wastegating up to Run 8. Note that much of this would be compatible with an overrunning turbo setup, and in fact might even retain the overrunning clutch as a device to preclude backdriving the mechanism in situations involving frequent rapid power change as in flat switching.
... Then the thread drifted in a fun way about six cylinder 645-710's. Well done there!
Up to the controversy about 6-645s actually being produced, this actually tied into the point about "non-turbo" 710s. Since there was not even a domestic market for six-cylinder 645s, the still greater balance-weight and blower considerations for a 6-710 mitigated even more strongly against even its suggestion.
There is another 'half' to the six-cylinder discussion. We might remember that the individual-small-turbo experiments actually predate the EMD mechanically-assisted turbo design, and one might think that the increasing adoption of various sizes of turbo for the road-vehicle market would eventually bring the cost of some appropriate turbo solution down to where it might be employed on a GM 2-stroke of 'whatever' number of cylinders, perhaps pre-boosting the input to a set of Roots blowers for better efficiency at higher speeds. What happened instead is that high-speed engine design, usually 4-stroke, with the 'better' turbocharging, rapidly got up first into the power range of the 'switcher' EMD 2-stroke family, and then increasingly into the range of road power. When you have Cummins or MTU engines that essentially run all day on the smell of an oily rag compared to a 6-567 and can be maintained by ordinary truck diesel mechanics using parts from the store, there's not much point even discussing bespoke light turbo 'solutions', let alone adapting longer stroke as well as larger bore to a 567 conversion, or even taking one of the select few 8-645 engines that might be in play up to using 710 power assembiies...
Isn't the real answer that with better wheelslip control railroads were going to higher horsepower locomotives? Think about it--30 years ago, 2000-3000hp was the market, now it's 4000hp+.
BackshopIsn't the real answer that with better wheelslip control railroads were going to higher horsepower locomotives? Think about it--30 years ago, 2000-3000hp was the market, now it's 4000hp+.
Part of the problem is that, just as with over 315K load or 6000hp single prime movers, the amount of practical low-speed TE controllable with traditional wheelslip control hits a limit per axle that is somewhat adhesion-limited. When you get rid of the situations that favor light four-axle power (suspension, guiding, cost, perceived higher-speed capability) and you get into the range of equipment size that no longer quite 'fits' on a four-axle chassis or that can be balanced to equalize weight on all axles, you'll go to six-axle power even when there are perceived advantages to 'four-motor' AC power. There is also the necessity of maintaining the range of parts and training for the shrinking four-motor 'fleet' (many of which survive only as derated yard or local power, and I see them more and more frequently being replaced or supplanted by older six-motor power like rebuilt SD40s).
On the other hand, I do see examples (both on NS and CSX) of clever use of four-axle power with road slugs -- on NS what appeared to be cabs-out GP60s with a 'matched' B slug in between, and on CSX a demotored cab Geep paired with a GP40 in transfer service coming off the Youngstown line near Ashtabula onto the Water Level Route. We've had road slugs from time to time come across the Broad Street crossing near Aulon in Memphis in what are probably transfer moves -- I don't remember if these were four- or six-motor, but they were paired with six-motor units.
Note that NS did essentially the same thing with the above configuration that a pair of something like dash-9s do coupled cabs-out ... but with additional complexity and the need to operate in married configuration. The idea may still make sense for places like those in the Pacific Northwest where BNSF still preferentially operates awesomely long strings of four-motor power in weight-restricted areas (think matched A-B-B-B-B-A and larger consists!) but I don't think this is generally typical for most Class 1 operation.
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