Do the GP units have horsepower ratings comparable to their SD cousins if they are in the same number series? Does a GP60 have the same HP as a SD60, for example. I would assume the GPs would have less tractive effort, because their size and weight is less than a SD model, and they have one less axle per truck, but I'm just wondering how the HP ratings compare.
Railroad Forums
GP vs. SD
- Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
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EMD GP-N and SD-N models have the same engines (and many other common components), and are catalogued as alternative applications of the asme powerplant. No railroad has wanted a 4-axle high horwepower unit from EMD since the GP60, and none wanted low-horsepower 6-axle units in the 1970s(*), so there was no "SD15-1," but in general the two types have been available as model pairs. Exception: EMD built the 2400 hp SD24 from 1959 to 1963, but there was no "GP24". Perhaps because they didn't trust their traction motors at such high ratings, EMD's 4-axle offerings in this period were the 2000 hp GP20 (there was no "SD20"(**)) and 2250hp GP30 (there was no "SD30" (***)).
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* Well, not factory-built: one CSX-predecessor rebuilt SD35 with non-turbocharged 1500 hp engines for hump pushing, and others have been rebuilt as 2000 hp units.
** No "SD20" built by EMD: some railroads have called their de-turbocharged rebuilds "SD20".
*** Though "Railroad Model Craftsman," sometime in the 1970s, published "imagineered" drawings!
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* Well, not factory-built: one CSX-predecessor rebuilt SD35 with non-turbocharged 1500 hp engines for hump pushing, and others have been rebuilt as 2000 hp units.
** No "SD20" built by EMD: some railroads have called their de-turbocharged rebuilds "SD20".
*** Though "Railroad Model Craftsman," sometime in the 1970s, published "imagineered" drawings!
actually the engine casings on the SD vs GP engines were different, at least through the 50 series. im not sure about the 60 series
the GP's used a lighter block
that was where some of the weight differences came from
but horsepower ratings were the same
the GP's used a lighter block
that was where some of the weight differences came from
but horsepower ratings were the same
Allen Hazen wrote: * Well, not factory-built: one CSX-predecessor rebuilt SD35 with non-turbocharged 1500 hp engines for hump pushing, and others have been rebuilt as 2000 hp units.you are thinking of 2 different units...
the "H-15" was rebuilt (de-turboed and de-dynamic braked) SD35's and SDP35's rebuilt by SCL in 1981
the "SD-20" were de-turboed ex-C&O/B&O SD35's rebuilt by C&O prior to the merger
Thanks, Crazy Nip! I new there were SD35 rebuilt both to 1500 hp and to 2000 hp, but couldn't have said for sure who had done which.
The bit about GP and SD units having different engine structure was new to me. EMD engines (before the 265H) had a built up, welded, frame, so I suppose it would be possible to use different gauges of steel in constructing differrent lots of engines: do engines intended for SD units have heavier steel in lots of places, or is it just a single add-on plate (sub-base?)?
The bit about GP and SD units having different engine structure was new to me. EMD engines (before the 265H) had a built up, welded, frame, so I suppose it would be possible to use different gauges of steel in constructing differrent lots of engines: do engines intended for SD units have heavier steel in lots of places, or is it just a single add-on plate (sub-base?)?
Be aware that some of the prior info is incorrect. There is no difference in an engine case and pan since the late 1960's between a GP and SD for turbocharged engines 16-567D3A (GP/SD35) up to 16-710G3A (GP/SD60). EMD's 300 and 303 engine parts catalogs verify this by part numbers and weights. Keep in mind there are about 15 different versions of 16 cylinder 645 turbo engines for rail applications alone so you are just as likely to find a different engine version in two SD40-2's as you are between a GP40-2 and SD40-2. These differences include but are not limited to oil pan capacity/style, pump configuration, flywheel style, and the "fuel economy generation" which is the 3rd number after the cubic inch displacement number which usually reflects changes in power assemblies, turbo, injectors, or other component involved in the combustion process. Engine cases have never been "lightened up" for a GP unless at special customer request
The H15 is basicaly a badly bastardized SD35. They took the turboed 2500HP 567D out. And replaced it with the 567B from old F3A and F3B. The Dynos were removed. And a really strange electrical cabinet installed. The units have odd manual transition lever with three settings. Hump Low, Hump High, and Road. Where road is the normal transtions. Hump High ro Hump Low locks the unit in a particular transition. These things had mucho problems and were allways quirky to operate.
B&O SD20-2 units were SD35 units rebuilt by B&O. Full Dash-2 cabinets and A 2000HP Deturboed 567D block were the features of this rebuild
IC SD20 (except the last four) units are rebuilt from various SD9, and SD24 units. Some were rebuilt from UP B units. All feature totaly new cabs. Partial Dash-2 cabinets, and roots blown 2000HP 567C or 567D blocks. New cabs were built for each unit. Basicaly these feature the tech you find in the IC GP11 rebuilds. The last 4 were rebuilt from SD35 units aftter PNC/MT Vernon suposedly sold off the last 4 rebuild canidates for the SD20 program. IC went out and hunted down 4 SD35 units. They are much like the B&O rebuilds.
B&O SD20-2 units were SD35 units rebuilt by B&O. Full Dash-2 cabinets and A 2000HP Deturboed 567D block were the features of this rebuild
IC SD20 (except the last four) units are rebuilt from various SD9, and SD24 units. Some were rebuilt from UP B units. All feature totaly new cabs. Partial Dash-2 cabinets, and roots blown 2000HP 567C or 567D blocks. New cabs were built for each unit. Basicaly these feature the tech you find in the IC GP11 rebuilds. The last 4 were rebuilt from SD35 units aftter PNC/MT Vernon suposedly sold off the last 4 rebuild canidates for the SD20 program. IC went out and hunted down 4 SD35 units. They are much like the B&O rebuilds.