Turbo barking and flaming stacks

[trainiac]

I'm not sure about those sound files. If a turbo was so severely unbalanced, that the sound became noticable in the cab, I would be recording the sound of the impending explosion, of the turbine. Turbo barks are sometimes amusing to listen to, but they usually come with reduced horsepower, and therefore, a slower than desired run. Since the sound has to travel through the turbo, and then out the stack, they all pretty much would have the same DB level, as heard from trackside.

In the case of a whining turbo commonly heard on EMD units, it seems to me that because they are spinning so fast (~18,000 rpm) that the smallest imbalance would cause quite a bit of noise. Kind of like an Athearn motor with an imbalanced flywheel. Also, it seems to me that kind of imbalance would travel through other components (hence causing a resonant whine) without too much harm--I've heard one unit with a noticeable (but not extraordinary) turbo whine for 6 years and it's had no turbo problems that I know of.

In the case of GP40 3202 "barking", it was definitely having issues, as at the time it routinely flickered a red glow out the stack following the "bark" and a reduction in rpm.

Now for a rather preposterous request...

Can anyone post their links (YouTube, or audio samples)...get ready...for the loudest, best (or worst if you're the engineer) sounding, most obnoxious, imbalanced good old noisy EMD turbos working upgrade. What's the noisiest YOU've ever heard? Passenger and/or freight?

How's this? These are two recordings from early 2007 of SLR freight trains heading upgrade in run-8 at 20-25 mph, with the same loco consist, two days apart. The middle unit in the consist was SLR GP40 3002, which for several months had an almost deafening turbo whine. It has since been fixed, but I don't know how it lasted so long without blowing anything.

http://trainiax.net/recordings/crec-slr ... 03-804.wav

http://trainiax.net/recordings/crec-slr ... 05-804.wav

Really Mike, Subaru's a nice car. Is it a WRX?

Not quite... A 12 year-old Legacy wagon. I could go on for a long time about how I've used it to haul cargo, go through snowbanks and tow other cars that were stuck in the snow, but that would be for another forum.

[mbta1051dan]

Funny, the 2nd recording isn't nearly as bad. Also wierd, the turbo whine coming from the 3002 sounds lower than usual. Is it running at reduced speed?

-Dan

[trainiac]

Funny, the 2nd recording isn't nearly as bad. Also wierd, the turbo whine coming from the 3002 sounds lower than usual. Is it running at reduced speed?

I think the fact that it was out-of balance reduced the speed. By all appearances, the engine was loading properly and was not running at reduced power to prevent wheelslip. Using another Athearn motor analogy, if you stick a piece of tape to one flywheel, the change in balance is enough to slow the motor down.

The difference in volume between the 2 recordings likely has to do with the distance from the train (a few hundred feet away in the first, trackside in the second) and the terrain (over a field and dam reservoir in the first, in trees and hills in the second).