Not sure what you mean by “compound boost” but turbo-compounding was used to increase the power of the Wright 3350 aircraft engine, one of the last in the era of high power recips that powered large aircraft.
If you meant multiple sources of boost, some of the MTU engines use “sequential turbocharging” with multiple turbos staged in and out to provide for rapid acceleration and good scavenging at all loads and speeds.
emissions
I recall one of the weaknesses of the turbo EMDs was the clutch. I have changed a few due to clutch failure. I do recall once, when working for Crowley, we changed out a turbo because it was at its maximum hours. An EMD rep came down to witness, because they usually failed before then.
The simple answer: DDs are small high speed engines, EMDs are larger medium speed engines.
That makes sense. That is the only turbo I know of that works like that. I thought Detroits might have had them as well but I guess EMD is the only one.
Yeah they are serious about the running hour interval on the turbo. (Same goes for the JW pumps, better change bearings and gear if needed or sparks start to come out we settled on 4200 hours max) If your magnet sweep in the sump at the turbo end turns up small pins that clutch is fini. Better to change at 30 khrs. With the 17:1 comp ratio turbos on the emission type power packs they seem to go quicker too.
Of course the similarities are two stroke, uniflow scavenging and unit injectors. . . .
Most EMDs in the offshore use are fitted with air flappers. One of the problems with the standard EMD emergency shut down is that in a gas rich environment, shutting down the fuel is useless, and an engine can run away with devastating results. I am sure glad that I am not the guy that found out about that. . . . but I have heard stories. . .
You engineer guys are way over my head, and rightfully so.In my experience, we had a lot more problems with the 71’s than EMD. I always wanted to go fast as I could, but the chiefs requested we stay at about 20 less RPM than max. It’s been a while, thinking that was 780 or so. They would give me 800 if I was tight on an ETA or trying to beat weather, but didn’t recommend it. I didn’t ask for it too often. Engineers were the heartbeat of our rigs, some captains took them for granted. Bad mistake.
EMD’s typically had 900 rpm as full. If your engineers told you to run 20 less, that should have been 880. Even at 800 rpm the engine load was probably less than 90%.
I have seen on more than one occasion the engines not being running at full throttle thinking they didn’t want to “push” the engines. In reality the automation was already set up to prevent that.
As I said, it’s been a while. 900 sounds right. Was hoping one of you guys would step up and engage my memory. I always took a glance at the RPM’s when I was running late. Wasn’t aware the automation was in effect. Circa 1995/2003? 16 and 20 cylinder EMD’s?
Yeah, 900, and, to be honest, that is where I would prefer that they were operated. . I know at Crowley back in the 80s, they would have us throttle back to meet schedules and for fuel efficiency (there is a story about flogging logs to get into port a day early or so, but was instructed by the Captain. . . .). You also have to be careful not to throttle back too much and risk overworking the turbo clutch. . . .
Back when I was doing Port Engineer work I supervised 2 EMD turbocharger swaps. Fortunately they were warranty jobs. It was on separate RRF ships but similar circumstances. They were operating the Hagglund cranes on deck so the load was oscillating from low to high. It made a mess of the gear train when the clutch gear came apart and dropped pieces into the gears below it.
Only massive failure of a 16 EMD was after a line bore and rebuild in a certain port during a shipyard period. Left the dock and stbd engine shut down after about 15 minutes. Then tried to “Pop the clutch” running hard with the wheels turning. Called techs in that were close by at the dock we stopped at. I stuck my head out of the wheelhouse and asked one (A long time respected engineer) what is the problem? He said " Cappy, you gotta put the oil back in them after rebuild". Went to sea that day, blew the doors off stbd engine about 100+ miles offshore., had to call Port engineer while at a nice company dinner that evening. Put engineer on the phone, He said" I got good news and bad news." Port guy in between his meal said “Give me the bad news first” , “We just blew the doors off Stbd engine” …'Well what is the good news?"…“I saved the block”. Can’t make this shit up. Won’t go on but had to return to port and swap barge at sea with a boat that had just entered the shipyard after we left. After second departure, had a new chief. Company’s decision, not mine.
The last ATB with EMD’s that I worked the CE & assistant made the small adjustments of the RPM’s from the engine room. The bridge would lay the sticks down to max which was slightly above 900 & we would monitor the exhaust temps. If a few cylinders or a whole engine started to run hot we would adjust air regulators that were next to the pyrometers that went to the throttles in the bridge. By keeping things clean & doing regular maintenance the exhaust temps were the only thing that matter & amazingly we never had to pull back due to oil & coolant temps.
Ditto to what @cmakin said about keeping the turbo charged EMD’s at high rpm to prevent damage. Keep them above 700/720 was always my advice to keep them working.
Always wondered why the other chiefs gave me max, now that you have enhanced my memory was 900,not 800. For whatever reason, my last chief insisted on 880. He served me well as a Maine Maritime grad which I have always had confidence in. (Didn’t attend there). I chose to go with that. We were both close to retirement and to debate 20 more RPM wasn’t worth the sour face at lunch or dinner. Perhaps he knew something I didn’t which is more than probable. His engine room was well taken care of, just keep me rolling was all I asked. My ex submarine guy before him was balls to the wall all trip long., An Outer Banker that is well reknown for his duck carving prowess. It was a pleasure to hand him tools when he needed us to help change a pack out. Which was not often.
About the only adjustments I would make to the RPMs in the engine room were to synch the engine speeds. . .
I sailed with a couple of ex submarine guys. There were quite a few on tugs in the 80s. . . most were, well, interesting. As far as changing a pack? I only ever had to do one at sea. . .I did as much as I could by myself, but did have to borrow a deckhand for a few minutes a couple of times.
Cmakin, those submarine guys were more than interesting. Had 3 over my career, loved every minute. Kept my crew entertained to no end, and reliable. What more could a throttle jockey ask? You are right, didn’t see too many after 80’s into early 90’s. Not to demean them in any way, they were all of shorter stature. Tough guys I would sit with on a bar stool anywhere.
I went to EMD school in '75. There were about 50 in the class. 5 or more were Navy. 2 were Chief motor machinists mates with dolphins. They were instructors at Great Lakes. We learned more from them than from the EMD instructors.