5,000 horsepower EMD SD80MAC 4100 in Conrail livery, May 2007.

(The original uploader was Ble909 at English Wikipedia., CC BY 2.5 <https://creativecommons.org/licenses/by/2.5>, via Wikimedia Commons)


GM-EMD logo.


The SD80MAC is a 5,000 horsepower (3.7 MW) C-C diesel-electric locomotive. It is powered by a 20-cylinder version of EMD's 710G prime mover, and was the second diesel locomotive by GM-EMD to use a V20 engine, since EMD's SD45 series. It introduced a wide radiator housing similar to GE Transportation locomotives and the placement of dynamic brakes at the rear of the locomotive, which is a quieter location, features that were incorporated into the SD90MAC and SD70ACe models. Key spotting differences between the SD80MAC and SD90MAC include no external rear sandbox on the SD90MAC, no rear lighted number boards on the SD90MAC, and the placement of the front numberboards (above the cab windows on the SD80MAC, on the nose on most SD90MACs). The SD80MAC also had recessed red marker lights in the nose, an identifying feature unique to Conrail (CR) locomotives, although Norfolk Southern (NS) had removed the lights on most of their former Conrail engines.

All 30 SD80MAC units built were delivered to Conrail, and the 28 production units were completed, tested, and painted at the former Pennsylvania Railroad shops in Altoona, Pennsylvania.

Prior to the 1995 merger with Union Pacific, Chicago and North Western Railway placed an order of 15 locomotives. Canadian Pacific placed an order as well but it was changed to SD90MACs. Conrail planned a second order of SD80MACs, but its new owners changed the order to SD70s and SD70MACs, all of which would be built at the Juniata Shops in Altoona.

Vale Mining of Brazil ordered a set of seven updated locomotives designated as the SD80ACe model. These locomotives feature Tier 1 compliant 20-710G3C-ES engines, with 5,300 HP (3.9MW) @ 950 RPM. The design is currently for export only, and these specific locomotives will run on Vale Mining's 5 ft 3 in (1,600 mm) broad gauge trackage.

Another broad gauge variant also came in 2012 only, that is, the EMD GT50AC, also known as the Indian locomotive class WDG-5, a smaller and lighter 135-ton variant, with an up-tweaked EMD 20N-710G3B-EC engine, capable of producing 5,500 HP (4.1MW) @ 910 RPM, to serve the Indian Railways, whose current tracks are weak to handle very heavy locomotives, just like how EMD GT46MAC WDG-4 was developed from SD70MAC by reducing the weight. The seven locomotives of the class were developed indigenously by Banaras Locomotive Works (BLW) of India. The locomotives are not a part of the SD80 series, but are completely based on it, making it the second International application of the V20-710 prime mover, after the Brazilian SD80ACe.

After the split of Conrail in 1999, the SD80MACs were split up between the Norfolk Southern Railway and CSX Transportation. Norfolk Southern received 17 units (numbered 7200–7216) while CSX got 13 (800–812, being renumbered to 4590–4602). The former Conrail units were the first AC traction locomotives owned by Norfolk Southern, with the railroad not ordering more until late 2008 with an order of General Electric's ES44AC. In late 2014, Norfolk Southern announced that they had reached an agreement with CSX Transportation to trade 12 EMD SD40-2 units (NS 3425–3447) for CSX's remaining 12 SD80MACs, leaving NS as the model's sole operator. They were delivered to the NS in April 2015.

In February 2020, following the beginning of COVID-19 pandemic, Norfolk Southern retired all 29 of its remaining SD80MACs, owing to their operational costs. Six units were sold to Canadian Pacific Kansas City (then Canadian Pacific Railway) as parts sources for their recent EMD SD70ACU rebuilds. The remainder of the NS fleet went to Progress Rail and were scrapped. As of January 2022, the Conrail Historical Society was in contact with Canadian Pacific Kansas City Limited hoping to have one SD80MAC set aside for preservation, after failing to make an agreement with Progress Rail.

CSX 4594, formerly CSX 804, and built as CR 4110, was scrapped in January 2014 after being used as a parts donor following a derailment in early 2009.



An NS South Fork crew was securing their engines for the night on Friday, 18 November 2016 when an electrical fire broke out in the cab of NS 7210 (CR 4118). There were no injuries, but the SD80MAC’s cab interior was completely destroyed. The unit was hauled to the Juniata Shops in Altoona where it was buried in a deadline until it was among the units that were sold off to Progress Rail. The unit met its end in December 2021.


CSX EMD SD80MAC No. 4593 in 2014.

(Dan from PQ, Canada, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons)


SD80MAC technical details

The technical details of this locomotive model are as follows:

Prime mover

  • Electro-Motive Diesel V-20 710G3B-ES
  • Displacement: 14,200 cubic inches (233 L)
  • Idle: 200 rpm
  • Full speed: 904 rpm
  • ube oil capacity: 510 US gal (1,900 L; 420 imp gal)
  • Cooling water capacity: 342 US gal (1,290 L; 285 imp gal)
  • Fuel capacity: 5,800 US gal (22,000 L; 4,800 imp gal)

Main alternator

  • Electro-Motive Diesel TA22-CA8A
  • Maximum voltage: 2600 V DC
  • Maximum current: 8100 A

Traction motors

  • 6 Siemens 1TB2830 AC motors mounted 3 each on 2 HTCR-2 Radial Self Steering trucks.
  • Rated output: 638 kW (856 hp)
  • Gearing: 83:16
  • Wheel size: 45 in (1,143 mm)
  • Max revolutions: 3,435 rpm
  • Starting torque: 16,300 N⋅m (12,000 lbf⋅ft)
  • Continuous torque: 12,900 N⋅m (9,500 lbf⋅ft)
  • Maximum voltage: 2,183 V


  • Maximum speed: 75 mph (121 km/h)
  • Starting tractive effort: 185,000 lbf (820 kN)
  • Continuous tractive effort: 147,000 lbf (650 kN)
  • Braking effort: 96,000 lbf (430 kN))
  • Weight: 210 tons (187.5 long tons; 190.5 t); 420,000 lb (190,500 kg))



Type and origin
Power type: Diesel-electric
Builders: General Motors Electro-Motive Division(EMD)
Models: SD80MAC, SD80ACe, GT50AC
Build date: 1995–1996 (SD80MAC); 2011–2012 (SD80ACe); 2012-2018 (GT50AC)
Total produced: 30 (SD80MAC); 7 (SD80ACe); 7 (GT50AC)
• UIC Co′Co′
Gauge: 4 ft 8+1⁄2 in (1,435 mm) standard gauge
Wheel diameter: 45 in (1,143 mm)
Length: 80 ft 2 in (24.43 m) (80MAC)
Length: 76 ft 6 in (23.32 m)(80ACe)
Height: 15 ft 5 in (4.70 m)(80MAC)
Height: 15 ft 10 in (4.83 m)(80ACe)
Locomotive weight: 420,000 lb (191,000 kg)(80MAC)
Locomotive weight: 432,500 lb (196,000 kg)(SD80ACe)
Fuel capacity: 5,800 US gal (22,000 L; 4,800 imp gal)(SD80MAC)
Fuel capacity: 4,900 US gal (19,000 L; 4,100 imp gal)(SD80ACe)
Fuel capacity: 1,981 US gal (7,500 L; 1,650 imp gal)(GT50AC)
Prime mover: EMD 20-710G3B-ES(SD80MAC)
Prime mover:20-710G3C-ES(SD80Ace)
Prime mover:20N-710G3B-EC(GT50AC)
Engine type: V20 diesel
Cylinders: 20
Transmission: diesel electric
Performance figures
Maximum speed: 75 mph (121 km/h)
Power output: 5,000 hp (3.7 MW)(80MAC)
Power output: 5,300 hp (4.0 MW)(80ACe)
Tractive effort Starting (SD80MAC): 185,000 lbf (822.92 kN)
Tractive effort Continuous (80MAC): 147,000 lbf (653.89 kN)
Tractive effort Starting (80ACe): 191,000 lbf (849.61 kN)
Tractive effort Starting (GT50AC): 125,893 lbf (560.00 kN)
Tractive effort Continuous (GT50AC): 91,047 lbf (405.00 kN)
Operators: Conrail, Norfolk Southern and CSX (SD80MAC), Vale Mining (SD80ACe), Indian Railways (GT50AC)
Numbers: CSX 4590–4602, NS 7200–7228, Vale 101-107, Indian Railways 50001-50007
Disposition: NS (SD80MAC): six sold to Canadian Pacific Kansas City as parts sources, remaining units sold to Progress Rail and scrapped and as of 2024 all (SD80MAC) locomotive sold off to Progress Rail have been scrapped.