Turbocharged

[rockislandmike]

Hey guys, how do I know which prototype models were turbocharged ???

I'm modeling MOPAC in 1980, and a # of them would still have the eagle emblazoned on the side of the long hood. But only the turbocharged diesels. So I'd like to assemble a list so I don't screw up accidentally. Thx.

rockislandmike

http://www.heatherandmichael.com/recklessandveiled/

[20_unknown]

Well....I think everything above 2000 HP was turbocharged.

On EMD roadswitchers, there will be one exhaust on the roof, a low-profile "silenced" type. Normally aspirated (non-turbo) engines will have two exhausts a few feet apart.

I know that every 35, 40, 45, 50, 60, 70, 80, and 90 series engine from EMD is turbocharged. Also, the 39s and the GP15T. GP15-1s and 38s were non-turbo, and I think all the shunters were non-turbo.

GE's? Hmmmm...I really don't know, since I only have to deal with C40-8s and C44-9s! I think the exhaust count (one or two) works for them, too. But I've been wrong before. This morning, even!

B-Dubya out -

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Modelling the Cape Breton & Central Nova Scotia Railway in HO

Inside every GE is an Alco trying to get out...apparently, through the exhaust stack!

[tankertoad70]

For GE, I cannot find anything other than their 70 tonners and smaller that came without turbochargers. I understand that the reason EMD had such an advantage in the switcher market was the lack of a turbocharger on their switchers. GE's first road lokie in the US was the U25B. It and everything since has a turbocharger.



Don in Orygun City

[NYCandHR]

Try this link out.

http://www.mopac.org/photos_diesel-freight.html

It is to the Missouri Pacific Historical Society. They have some pictures on the website.

Are you modeling the Union Pacific merger? I might have a few pictures I took early '90s with the units in Armour Yellow with Missouri Pacific lettered on the side. The pictures would most likely be GP38 type. They are nothing fancy; they were taken as I was getting started in photography.

Good luck,

Joel

[rockislandmike]

Thanks, Joel, I'll take a look (the Fallen Flags site has whackages of pics too, which is where I did quite a bit of my research based on the date I'm modeling).

I'm modeling MOPAC pre-merger with the UP. That's one of my fave things about 1980 - it's just b4 all the mergers, but some of them have been announced, allowing me to include some crossover locos down the road if I feel the need.

rockislandmike

http://www.heatherandmichael.com/recklessandveiled/

[BN_Walt]

All GE's I have ever been around have been turbocharged. EMD engines will have A single stack above the main generator and or traction alternator if they are turbocharged. Non turbocharged EMD's usually come with two stacks that are centered between the cab and the cooling fans on the rear of the engine. Many have four small stacks, most from rebuilding, or refitting of exhaust manifolds. Engines that are de-turbo'ed as a result of rebuild or remanufacture will also have the two or four central mounted stacks.

[rockislandmike]

Thanks again everyone; this list will come in very handy when I'm painting my own units, and selecting factory painted ones as well.

rockislandmike

http://www.heatherandmichael.com/recklessandveiled/

[PowerEngineer]

quote:

---

Well....I think everything above 2000 HP was turbocharged.

On EMD roadswitchers, there will be one exhaust on the roof, a low-profile "silenced" type. Normally aspirated (non-turbo) engines will have two exhausts a few feet apart.

I know that every 35, 40, 45, 50, 60, 70, 80, and 90 series engine from EMD is turbocharged. Also, the 39s and the GP15T. GP15-1s and 38s were non-turbo, and I think all the shunters were non-turbo.

GE's? Hmmmm...I really don't know, since I only have to deal with C40-8s and C44-9s! I think the exhaust count (one or two) works for them, too. But I've been wrong before. This morning, even!

B-Dubya out -

--------------------------------------------------------------------------------

Modelling the Cape Breton & Central Nova Scotia Railway in HO

Inside every GE is an Alco trying to get out...apparently, through the exhaust stack!

---

id=quote>id=quote>
In addition to the above, the SD24 was also turbocharged (567D3), as was the GP20 (567D2) and the GP30 (567D3).

PowerEngineer

[Nigel]

And there were a few MP15T, MP15AC's with turbo V8's instead of the normal non-turbo V12. Same engine as used in the GP15T.

All Alco road locomotives were turbo.

No Fairbanks-Morse locomotives were turboed.

Nigel F. Misso

[tomfassett]

I'm no expert but--here's all I can add to the discussion of turbos:

From what I understand, some EMD engines had a Roots type supercharger as opposed to a standard turbocharger. I believe all GE road units use standard turbochargers. Most EMD road units from the E on had some type of forced air system. The E series had a low pressure "turbocharger" which was the forerunner to the modern superchargers. I seem to remember the 2000 HP threshold as a good reference as well. A normally aspirated prime mover can lose as much as 40% of its power at 10,000 feet of altitude (usually about 4% per 1000 feet, if my memory is correct). Thus, it would be almost impossible to use non turbocharged road engines in anything but low to medium altitude specialized use operations (seaports, small trains, etc).

There were some GP18s and GP9s which were originally non turbocharged, but most were later upgraded. I know a lot of railroads rebuilt various units without turbochargers. Most were considered "boosters." SP rebuilt a few GP35s using 645 engines without turbochargers. These were rated at 2000HP and designated GP35Rs. I don't recall the engine numbers. I know the Belt Railway of Chicago even has some de-turbocharged SD40s. Try running those over the Rocky Mountains...

I don't ever recall any later MP road units without turbochargers but I could be wrong (I am certainly NO expert on the MP)...

A little turbocharger trivia...

A Roots supercharger differs from a standard turbocharger in the way it "aspirates," or feeds air, to the prime mover. One main advantage of a Roots type supercharger is that it produces higher power at lower rpms. The Roots is a "positive displacement" type of supercharger which creates a "positive" pressure zone in the intake of the prime mover. A turbocharger works like a standard fan in that the air is driven into the intake by centrifugal force as the curved impeller blades rotate, being "thrown off" at the rim or the housing. This is basically the same design as the defroster fan in your car or an exhaust fan in a bathroom. The impeller is driven by the exhaust pressure exiting the exhaust manifold. The Roots type is generally driven by the prime mover and usually has a flatter torque curve (based on rpms) than a turbocharger.

One more note of interest. EMD turbochargers use a clutch assembly driven directly off the prime mover which spins the impellers at very low engine speeds. This gives the engine an instant "boost" when the prime mover is throttled up. When the exhaust pressure reaches an adequate point that it can drive the impeller at speed, the clutch releases. GE units use a standard turbocharger without a clutch system. When the prime mover is throttled up, there is a temporary condition where the engine is "starved" for air resulting in too rich a fuel mixture. This excess fuel is what creates the characteristic "black cloud" out of the exhaust port which GE units display when starting up. Within a few seconds, the engine speed is sufficient to boost the exhaust pressure to properly drive the turbocharger impeller blades at a sufficient speed to supply enough air to the intake to restore the proper fuel-air mixture.

So now you know...

Tom

Edited by - tomfassett on 09/25/2002 04:04:30

Edited by - tomfassett on 09/25/2002 04:07:09