mtuandrew wrote:I don't see that EMD offered a turbocharged 8-567, but was there ever any interest by railroads in acquiring or rebuilding E-units to 2 x turbo 8 configuration for lighter weight? (or for that matter, keeping the A1A trucks and moving to 1 turbo 16-567)As far as I know, the first turbocharged “8” was the 8-645E used in the GT18 export model. The first production of that seems to have been the GT18MC for South Africa, supplied from 1974. Whilst the GT18 did have wider sales, it should not surprise me too much if in part EMD developed the GT18 in order to match the GE U15C, which South Africa also bought in parallel. I doubt that the GL22C could have been pared down enough weightwise to match the South African version of the U15C, so the “turbo-8” was required. If it happened that way, then it was déjà vu for EMD. It broke into the hitherto GE-dominated South African market in 1966 with the GL26MC. And it apparently got there by making its G26 smaller and lighter than the preceding G16 to the point where it was more-or-less a ringer for the GE U20C, by then very popular in sub-Saharan Africa.
I did once hear anecdotally that the South African GT18MC fleet was not entirely comfortable in its branch line and secondary service role, involving as it did frequent throttle changes, which the turbocharger overrunning clutch did not much like.
Back to the twin 8-567CR idea, that configuration was actually used in the Henschel KK16 locomotive, a double-ended cab unit built for Egyptian Railways in 1957, an EMD licensed design. So the basic engineering work had been done, and one imagines, had been signed-off by EMD.
In fact all of the cylinder count variants, six through sixteen, of the 567 engine were used in twin-engined locomotive installations. A 6-567 pair installation was used by Henschel in the seven B-B centre-cab diesel-hydraulic locomotives it built for South African Railways in 1958.
I suspect though that a twin 8-567 installation would have been exceptionally noisy, and not a good choice for passenger service. New Zealand Railways had a fleet of the somewhat modified G8 model, in-service from 1965. Singly, in suburban passenger service they seemed to be noisier than the G12s. If the train stopped on a downgrade with couplers compressed, the engine vibration was transmitted back to the leading car. And the transition “bump” was very noticeable. In pairs in freight service, when running at notch 8 upgrade, they would develop a low frequency beat note that as well as being very loud, on a still night would rattle windows and doors in houses several hundred yards away. Maybe aviation-type synchronizing devices would have helped. (I’d say that a pair of 8-567CRs were more obnoxious, noise-wise than four Wright Turbo-Compounds on a DC-7C.) Whether the multiple 8-645s would be any quieter than multiple 8-567s I don’t know.