?? "SD-58" ??

[Allen Hazen]

There was never an SD-58: I made the model designation up for something related to an SD60 as an SD38 is to an SD40: similar carbody and mechanical parts, but a non-turbocharged engine.
To the best of my knowledge, EMD has never marketed (at leasst for locomotive applications) a Roots-blown 710, but -- given the fundamental similarities between the 645 and 710 engine designs -- such a thing ought to be workable. Now, several railroads seem to have decided to de-turbo elderly SD40, turning them into ersatz SD38, for low-speed (switchin, hump pushing...) service. Turbocharged engines are more efficient than a Roots blown, but apparently -- if you are planning on using the locomotive exclusively at low power settings -- the engine efficiency and maintenance aspects of a Roots-blown engine seem more attractive than those of a turbocharged engine never run in the higher notches.
So. We are now getting to the stage where SD60 are being retired. Some are being cascaded for re-use as, e.g., work train power (cf. separate post on Metro).
Two questions: is there some reason why a 710 engine couldn't be rebuilt with Roots blowers? And, if it IS technically feasible, would it make operational/economic sense to de-turbo an SD60 for low power use?
In other words: There has never been an SD58, but is it plausible to think there some day MIGHT be?

[Allen Hazen]

The above was inspired by a note in the September 2004 "Trains" (locomotive column). Some months earlier there was a report that Metro (LA commuter agency) had bought second hand (ex-Amtrak) F40 and second-hand SD60, and wanted to "cross kit" them: rebuild the F40 (with lengthened carbody to accommodate separate HEP diesel generator set) to ??3800?? hp passenger locomotives with the engines from the SD60, and rebuild two of the SD60 with 645 engines for work train service. This was extensively discussed on this forum in the string titled "F45 Rebuilds".
The scheme has fallen through. Metro asked for bids from contractors to do the kitbashing, and the country's locomotive rebuilders apparently unanimously laughed in their faces. Current plan is to rebuild the better F40 in kind, and keep two SD60 for work train service.
So the scenario in which an "SD58" might be built has come to pass: SD60 are being cascaded to secondary service.

[mxdata]

Allen, answering your two questions:

Because of differences in the rear timing gear train and its housing between the 710 and 645 engines, building a roots blower 710 would require the design and manufacture of a number of fairly expensive parts which presently do not exist. With little potential for new sales of roots blower engines, this expense would be very difficult to justify.

Consequently the best economic solution if you absolutely MUST de-turbo a 16-710 engined locomotive would be to sell the 710 and buy a rebuilt roots blower 16-645 to install in its place. The engine footprint and the height of the crankshaft centerline above the mounting pads is the same. However, this is also difficult to justify since you have many equipment issues to resolve in making such a substitution, particularly the positioning of the auxiliary generator and equipment blower on the main generator (since the PTO on a roots blower engine is between the blowers, not on the right bank side like a turbo engine), and a lot of sheet metal changes needed to accomodate the air inlet and exhaust system. You also would have a number of electrical and software modifications needed, I won't get into all of that here. Once you get it all done, you are going to have to write a special parts book so your shop forces know what to order when they need parts for this locomotive, because the "thing" you have created is NOT covered in EMD Parts Catalog 190.

It ends up being a lot of expensive work just to take a unit which has a Brake Specific Fuel Consumption around .330 Lb/BHP-Hr and increase the BSFC to .403 Lb/BHP-Hr while cutting the horsepower almost in half, in order to save the expense of rebuilding a turbocharger every few years!

I would think the most practical overall solution in this scenario might be to overhaul the engines, installing power assemblies having new pistons, rings, and liners and also install freshly rebuilt fuel injectors. The primary things that kill turbochargers are foreign material damage to the exhaust turbine from broken rings, and overheat overspeed failures due to carbon fires in the air box and exhaust manifold. If you take good care of the power assemblies and injectors, you end up buying fewer replacement turbos. The turbo drive clutch on the 710 is in the engine gear train and can be replaced independently from the turbo.

Of course it isn't my locomotive or money in use here, if I was the one paying the bills maybe I would have a different opinion!

I am not surprised if the rebuilders were not enthusiastic about this job. It typically costs $50K to $75K to put together a quote for an extensive rebuilding project, and with TWO types of units that have to be quoted, it would be twice the time and effort to assemble the quote, for a job that would only involve a couple units and would be a complicated mess!

[Allen Hazen]

Thanks, MXData!
That the conversion would increase specific fuel consumption and decrease power isn't, by itself, enough to keep it from being done: after all, people ARE de-turboing GP40 and SD40 (and NS seems to be converting GP50 to "GP38-3"), and this must have similar effects on power and fuel-efficiency. (Or do you think the people deturboing these 645-engined types would be better advised to "overhaul the engines, installing power assemblies having new pistons, rings, and liners and also install freshly rebuilt fuel injectors"?)
But the fact that there are large numbers of factory-built Roots blown 645 engines means that deturboing a 40-series or 50-series locomotive can be done with available components and blueprints, whereas creating an "SD58" would involve serious new engineering and manufacturing, which totally queers the economics of the conversion!
(Sorry I didn't figure this out for myself, and thank you for giving me a well-informed answer! ... I have to admit that I posted this question after reading the exasperated replies to Terry C: could I, I wondered, ask a question about a fictitious locomotive model that would be interesting to people interested in real locomotives. I don't know about my question, but your answer certainly is!)

[mxdata]

Allen, I don't think anybody will get you confused with TerryC. Just don't start sniffing Floquil.

You hit it exactly with your last post. Downgrading a 40 to a 38 can pretty much be done out of the parts book (it is still expensive). Downgrading a 50 to a 38 takes a little more work (particularly in the carbody). But downgrading a 60 series locomotive to a roots blower configuration gets to be a really major project.

Most of the folks that have a lot of turbocharger failures on EMD locomotives are the ones that seldom take a look in their engines air boxes to see what is going on in there, or never change fuel injectors between overhauls. Running EMD engines with broken rings or bad injectors is complete economic nonsense and will kill a lot of turbochargers at $25K to $45K a turbo.

The big problem on many railroads that run with high turbo failure rates is that they keep changing turbochargers when they would be better off changing the Chief Mechanical Officer. For the cost of just a couple of turbochargers you can hire somebody who knows how to maintain an EMD engine properly, so that you aren't throwing away a far greater amount of money by failing turbos repeatedly.

[Jamshid]

Along with FODs and faulty injector nozzles, clogged air filters and faulty FES(pressure switch in central air system (CAS), wich is activated when filters are clogged and pressure difference between CAS and loco hood exceeds a preset value) systems should be concerned.

One of most important FODs is accumulated and hardend soot. When loco is operated under low powers for a long time(Shunting duty cycle) it develops soot and throught the time these soot will be hardened and when loco once used in full power (for instance in load tests, autotrage ) these soot is detached and acts as FOD.

Due to this problem:
1. EMD uses screen in inlet of turbo
2. Root blower engines are more favorite for shunters
3. Spark arrestors used mainly for shunters to prevent dissipation of ablazing soot (spark)

So technically root blowen engines are more suitable for shunters and lower efficiency of these engines is not so important due to their low duty cyle.

Actualy low power engines are preferred for shunters, and any kind of 710 engines are irrevelant for shunting, to the best of my knowledy GE used CAT engines for its low power U10B locomotives...

Making heavy Shunters out of withdrawn locomotives with new low power engines (I mean less than 1000 hp) is a promissing bussiness, I think.

....will kill a lot of turbochargers at $25K to $45K a turbo.

Would you please clear it which turbo worth 25000$ and wich 45000$
(Because of similar architecture I don't expect this amount of difference)

[mxdata]

Most rebuilders of EMD turbos bill according to the repairs required. Rebuilds typically run in the $25K US range if there is light to moderate damage to rotating components. If a failure results in damage to the compressor or turbine bearing support, or to the main housing, so that the matched set of aligned support structures (called the doweling assembly) have to be replaced, a failure can run up into the $45K range. Overheat overspeed failures frequently result in damage to the main structural components and the repairs tend to be toward the top of the price range.

The market for locomotive rebuilds less than 1000HP in the US is very small.

[MEC407]

Apologies for resurrecting an ancient thread, but I've been thinking about this topic and would appreciate feedback from Allen, mxdata, and anyone else who wants to weigh in.

Let's say that a railroad has a few SD60s that are no longer particularly useful or efficient for mainline road freight service. Let's also say that this railroad wants to get rid of the ancient 567-powered units they've been using for yard switching.

In lieu of deturboing their SD60s, how cost effective would it be to configure the SD60s as slug mothers? If you paired a six-axle slug with an SD60, you'd have about the same amount of power and tractive effort as a pair of SD38-2s (preferred yard power on many railroads), but presumably much better efficiency. The 710 in the slug mother would spend more time in higher RPMs (due to powering all those extra traction motors), which -- if I'm understanding correctly -- is more efficient and "better" for the turbo than if it spends most of its time at lower RPMs.

Am I all wet or would this be a plausible solution?

[JayBee]

In lieu of using a SD60 here is what CP's SD30C-ECOs look like.

http://locoslides.com/CP_Rail_slide_list_5.html

scroll down to the second photo.

Also KCS's SD22ECOs would be good. With the Turbo V8 they should be more fuel efficient than a non-turbo V16.

http://www.rrpicturearchives.net/showPi ... id=1871233

[Steve F45]

just out of curiosity, how do these small turbo V8's sound compared to their turbo V16 and V20 counterparts?

[MEC407]

Do a YouTube search for GP22ECO and you'll find many videos of them.

[MEC407]

Apparently BNSF's solution to the "What should we do with SD60s?" question is to repaint them, derate them to 2999 HP, and modify the pilots so they'll clear hump yard retarders:

http://www.rrpicturearchives.net/showPi ... id=3365941

[JayBee]

Apparently BNSF's solution to the "What should we do with SD60s?" question is to repaint them, derate them to 2999 HP, and modify the pilots so they'll clear hump yard retarders:

http://www.rrpicturearchives.net/showPi ... id=3365941

It is a "paper" derating, BNSF did the same thing with several hundred SD40-2s, derated them from 3000hp to 2999hp. This tells the people that assign them to uses that they are now yard and local power, rather than road power. They have also equipped three of them with RCL equipment for Remote Manpack operation.