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.
You are correct. I changed it from turbo to supercharged, AKA “Blower”.
Still don’t know why there wasn’t a blower 710…
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 engi
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.
Fuel economy. The blower engines are just horrible in the upper notches.
Here’s a 12-710 running without any exhaust boost into the turbo:
Thanks for being considerate … but I actually forgot about the 8-710 in the ECO package. The 8-645 was trouble enough…
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?
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
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-
645s.
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.
Peter
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.
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.