GP38-2 VS. GP39-2

[Anonymous]

What`s the difference between the GP38-2 and the GP39-2 ?

N.D.

[Justicar]

350 horsepower, IIRC...we have a pair used exclusively by one of our transfers...not sure why. I think its our only two.

CPR St Paul

[Anonymous]

To be more specific, the GP-38 has a "non turbocharged" 16 cylinder 645 series engine, while the GP-39 has a Turbocharged 12 cylinder 645. The 38 has 2000 horsepower, while the 39 has 2300 HP. Now, to anticipate your next question, I would prefer the GP-38 over the 39. The reason is maintenance costs. The 39 was proven to have a little bit better fuel mileage, but that really depends on the application. The added maintenance of the EMD turbocharger will offset these costs in most applications. One notable exception however, is the GP-35. Aside from the electrical nightmare of these units, they are very efficient compared with other locomotives of similar vintage.
If you want to hear about a REALLY fuel miser though, the ALCO 539 switchers can't be beat. Sure, lots of smoke when they load up, but when idling, (as most locos do 85% of the time) they are almost as efficient as a sub compact car.
Of course i'm also using the weight to horsepower ratio to support these claims...

Todd C.

[Anonymous]

Thanks you answered my question.

N.D.

[mudchicken]

Santa Fe had both. Almost never saw a GP-38 in Colorado unless it was in yard service and that was rare. Couldn't breathe in this altitude with a rack setting set closer to sea level. The GP39-2's were everywhere including light intermodal trains. And the GP-38's (no turbo)were notably loud with a deep, low engine noise....

[prograilfan]

Anonymous

What`s the difference between the GP38-2 and the GP39-2 ?

Any difference in the spotting features of these locomotives?

 

[Backshop]

They both have two radiator fans.  The 38 has two regular exhaust stacks while the 39 has a single turbo exhaust farther towards the front.

[Overmod]

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[BEAUSABRE]

ATSF bought the turbocharged 39 because it didn't lose horsepower the way mormally aspirated 38's did on high elevation track. Air thins out the higher you go, so a non-turbocharged engine runs rich (and smokes), wasting fuel and since the fuel isn't completely burned, you lose power. 

[Leo_Ames]

Superior high altitude performance is only part of why Santa Fe went with the GP39-2.

Not long before they ordered their first GP39-2's, the Santa Fe helped fund and participated in a study that compared cab air quality in a few months old Santa Fe GP38, a SP SD45 with an overhauled prime mover, a sister SD45 due for an engine overhaul, and a SP U33C. The winner by a fair margin were turbocharged locomotives. 

I'm sure that not only factored in the decision to go for the GP39-2 over the GP38-2, but also influenced their decision to retain the turbo over the following decade when rebuilding early 2nd generation EMD's.

[Shadow the Cats owner]

This should tell you how much a turbo means to a modern car engine.  I have a 2020 Chevy Trax you know one of the smallest SUV's that GM makes.  Well a couple weeks ago it blew it's turbocharger apart.  My car went from 180 HP to maybe 70 HP and could not even climb a small rise on the highway without dropping a freaking gear.  Now do remove the boost from 16 cylinders of locomotive put it above 5K feet and wonder why the Santa Fe bought more GP39-2's than anyone else.  

 

I saw an old tonnage rating for the Rio Grande.  Their old F's for the Zephyr where only allowed 100 tons of train per unit at 10K feet.  

[mudchicken]

Also explains why GP-20u's were so common out here as opposed to GP-7, GP-9 and CF-7's....The slug mothers at Pueblo and La Junta had different rack settings. The SD-39 and SD-26 units thrived out here for a similar reason, but also the lugging issue at low speeds over the hills made them attractive.