EMD SD40 series official thread (covers all variations)

[SD45Jim]

I have always liked the looks of the two large locomotives from the late 1960s and 1970s. Which locomotive was better, the SD45 or the SD40? I know that most SD45s have been retired from Class 1 railroads, but I understand that it is mostly because their 20-cylinder engines were not fuel-efficient. But which one pulled better and ran better?

Jim Sherwin

[metman499]

Every engineer I have ever talked to rates the SD40 and its -2 cousin as the best locomotives they have ever ran. Certainly better than any GE.

[Justin B]

The downfall of the SD45 was indeed the 20 cylinder prime mover, but the problems were not fuel efficiency. In fact the 20-645E was slightly more fuel efficient than the 16-645E (18.6 Hp/Gal/Hr for the 20, 17.9 for the 16). The problems were in the block (too much flexing) and the crankshaft (too weak), and of course the extra maintenance. By the time the SD45-2 had been rolled out the problems in the 20-645E had been fixed, but the railroads had already decided on the 40-2 and were wary of anything with 20 cylinders.

The SD40-2s are IMO the best locomotives ever built.

[LCJ]

I particularly liked the SD40-2 units that were built in the late '70s, such as the big order from Conrail in '78. Good, strong power, very comfortable, less cab noise, excellent controls.

I remember running them on TV trains at 70 mph on the Chicago line after the slow orders were all gone. Lot's of fun. Crank 'em up, and get 'em in the wind!

Honestly, SD50s were a disappointment in many ways, even though mechanically they weren't much different from 40-2s.

20 cylinder 645 PMs were a bigger success (even to today) in marine and fixed power supply applications.

[dave76]

I read the problems with the SD45 initally were the weak crank and block.
But I also heard those problems were adressed and corrected just before the -2s went into production. The reason I heard most SD45s were rebuilt in the 80s and 90s with 16-645s was because the cost of the 20-645 block was just a lot more, and the 16 was more readly available. In the 90s Wisconson Central aquired mostly second hand SD45s from various roads and rebuilt them with 20 cylinder engines and used Q Tron software, which greatly improved fuel consumption and engine control, and up till the merger with CN they used the SD45s on just about everything with the 3600 HP rating. They would normally run them in 3s. These engines acording to them were great pullers.

[dave76]

BTW the SD45 is my favorite engine.

[mxdata]

The early production of the 20-645E3 engines in the SD45's encountered problems with cracks developing in the welds at the attachment points of the "A" frames which support the crankshaft. EMD went through several successive improvements in the size and penetration of the weld beads in production, and also offered similar improvements for crankcases which were sent in for unit exchange (UTEX). They introduced an improved version of the "E" crankcase on original serial numbers after 72J (September 1972) which had additional features, including an "A" frame with a larger footprint, sometimes referred to as the D-foot "A" frame. The production of the SD45-2 model with the improved crankcase were generally quite successful in service, but some customers became wary of the failures with the early versions, and turned to the 16 cylinder units. As several others have noted in their responses, the 20-645 engine generally does quite well in marine and power generating applications where it is not bounced down a railroad. The Dash-2 control system on the SD40-2 and SD45-2 proved very successful on both series of locomotives.

[missthealcos]

Seems to me the ex Santa Fe SD45-2's wouldn't still be in service if they weren't good locomotives.

CN seems to only be disposing of the SD45's that didn't make it into the rebuild/Qtron program.

[dave76]

I also heard CSX is also converting the SD80MACs to the 16-710, not due to problems with the 20-710, there now in for there full overhaul ,but just because its cheaper for the 16, and will consume less fuel. The 20 cylinder engine costs quite a bit more, I don't the cost offhand but someone posted the difference at an earlier post sometime back.

[Engineer Spike]

I have noticed that the SD45 has more top end. When I got to run BN's SD40-2s, they seemed to accelerate good up to 35-40mph. Over this would be a struggle. The 45 was better. The 45 was also designed to replace multiple 4 axle units in high speed service. The SD40 was a more all around engine.

[RK]

Hi there,

Over at TrainOrders.com, no one is saying anything about the CSX SD80MACs being converted to the 16 cylinder engine. They are saying a number of them have been through the overhaul and kept their 20 cylinder engines.

[crazy_nip]

the 20 cyl 710 are being replaced as the engines fail

I think at this point 3 or 4 have been replaced due to failures

think the numbers were 812, 804, 814 or 810

something like that

[LCJ]

I have noticed that the SD45 has more top end. When I got to run BN's SD40-2s, they seemed to accelerate good up to 35-40mph. Over this would be a struggle. The 45 was better. The 45 was also designed to replace multiple 4 axle units in high speed service. The SD40 was a more all around engine.

Yeah -- no question -- more horsepower equals more speed. Like the difference between a GP38 and a GP40. GP38s lose it after 30 mph, while adding 1000 hp pushes back the counter-voltage from the rotating motors.

[westernrrtx]

I ran the SP 3200's SDP 45s in early 1980's. They were really fun to run. I don't know how they compared in fuel and mantanence costs though.

[EMD567]

What are the first and last production units of the SD-40-2? Are they still in service?