UP 2581

Thursday mourning at Sullivan,IL @ 3:45 am was a local with the UP 2581. This unit was origanally a GP-40. It sounds like a GP-38. Did the UP de-turbo this unit? If so was this part of a group of down grades?

RRPictureArchives.net says UP 2581 is a GP38-2.

ic9623 wrote:Thursday mourning at Sullivan,IL @ 3:45 am was a local with the UP 2581. This unit was origanally a GP-40. It sounds like a GP-38. Did the UP de-turbo this unit? If so was this part of a group of down grades?

Originally delivered to D&RGW in 1967 as GP40 #3067, this unit was indeed "downgraded" by UP to a GP38-2 in 1998, and renumbered 2581. The rebuild to GP38-2 standards included, among other things, the replacement of its orignal 3000 h.p. turbocharged EMD 645E3 prime mover, with a 2000 h.p. EMD 645, thus giving it that GP38 "sound" you had noticed...

If the turbo is taken out, the sound of a GP40 will be the same as a 38. Both use the same engine. I could be wrong but I don't think they swapped engine types, they just took the turbo out and replaced it with a roots blower or something that performs the same function as one.

It's not necessary to replace the engine to convert a GP40 to a 38--only to swap the turbocharger for a Roots blower (along with some other minor changes).