EMD Fuel Consumption Turbo vs. Roots

I have a question. My experience has always been with roots blown EMD engines. How does fuel consumption compare between a roots engine and a turbo charged engine.

Thank you,

TEB

Depending on what Rack setting that you are running, I have found that the old 1 gallon per day per horsepower works out to be pretty close.

Way back when I was on a Boat with 16-567-C (with 645 packs) we were burning right around 3,000-3,200 gpd (each engine rated at 1600 hp). Last boat that I was on has 16-645-E5 and burned around 5,600 gpd with a 233,000 barrel barge in ballast and 6,200 gpd loaded.

These figures were running at the Max RPM and at a .92 rack. If you can get the wheel house to pull them back a little you can save a lot of fuel but good luck on that! I even went so far to prove that if we cut back around 25-50 rpms we could save a lot of fuel and lose NO speed but it was like talking to a stone wall. You are only going to push a Steel Brick so fast.

A turbocharged engine should burn less than a comparable engine with a Roots blower. A turbo uses energy from the exhaust stream to power the blower where the Roots blower is engine driven.

[QUOTE=Chief Seadog;141700]A turbocharged engine should burn less than a comparable engine with a Roots blower. A turbo uses energy from the exhaust stream to power the blower where the Roots blower is engine driven.[/QUOTE]

yes this is true but would you not get a HP boost as opposed to a fuel burn decrease if you run each at the same rack setting. Just getting more pop from the same squirt.

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[QUOTE=TheEmpireBuilder;141620]I have a question. My experience has always been with roots blown EMD engines. How does fuel consumption compare between a roots engine and a turbo charged engine.

Thank you,

TEB[/QUOTE]

Just want to compliment you on the excellent username you picked. Are you a maritime man or a train guy? I’d say train guy by the name.

btw, the Great Northern was the greatest railroad ever! Let’s give it up for James J. Hill…

[QUOTE=Tugs;141650]Depending on what Rack setting that you are running, I have found that the old 1 gallon per day per horsepower works out to be pretty close.

Way back when I was on a Boat with 16-567-C (with 645 packs) we were burning right around 3,000-3,200 gpd (each engine rated at 1600 hp). Last boat that I was on has 16-645-E5 and burned around 5,600 gpd with a 233,000 barrel barge in ballast and 6,200 gpd loaded.

These figures were running at the Max RPM and at a .92 rack. If you can get the wheel house to pull them back a little you can save a lot of fuel but good luck on that! I even went so far to prove that if we cut back around 25-50 rpms we could save a lot of fuel and lose NO speed but it was like talking to a stone wall. You are only going to push a Steel Brick so fast.[/QUOTE]
Spot on all points, especially the stone wall. Before the electronic consumption monitors, I always used the factory test stand report to calculate consumption on long tows. If the engines haven’t been too modified over the years, I found the graphs to be very accurate. It also shows the drastic reduction in fuel consumption by backing off a few RPMs.

[QUOTE=injunear;141712]Spot on all points, especially the stone wall. Before the electronic consumption monitors, I always used the factory test stand report to calculate consumption on long tows. If the engines haven’t been too modified over the years, I found the graphs to be very accurate. It also shows the drastic reduction in fuel consumption by backing off a few RPMs.[/QUOTE]

I always hated when they put Engine Tachometers in the Pilot House. I would get calls saying that one engine in running 5 rpms less than the other one. I guess they never heard of a floating rack. I actually had one Skipper that would sit there with a Calculator to convert the Shaft rpms to M.E. rpms. He would drive me nuts over a could of rpms difference.

I did a relief job on one of our East Coast Vessels. When reading the old logs (The First Thing that I would do when working on a different boat) I noticed that they were logging the M.E. rpms as 910. Well as EMD’s are tagged with a Max rpm of 900, I told that Assistant to run them at 900 MAX. I got called up to the Pilot House for a little talk to the Captain, he wanted to know why the engines sounded different. I explained the rpms to him and said I did not care how His Chief ran the boat but I was not going to over rev them, which to his credit he did not have a problem. As it turns out they had been running those Mains at a Dead Rack and never allowing them to Float, which to me is not the best way to run any engine.

Back when I was sailing, I always ran the Mains as fast as I could do safely. The limiting factors were, Engine Exhaust Temps, Main Engine Lube Oil Temp and The Rack (I would run them until I hit Dead Rack and then back off until the Rack started Floating). As long as these factors were with in normal operating levels I would run them all the way up to Max Rated RPMs. It used to drive me nuts when the Captain would call down and say run them to the Max as I ALWAYS did. I tried to explain to them that I do run them to the max, now some did get it but others never seemed to get it and would bitch and moan about a couple of rpms, which if they had taken a couple of minutes to think about it did not make a damn difference in the speed we were making!

[QUOTE=c.captain;141703]

btw, the Great Northern was the greatest railroad ever! Let’s give it up for James J. Hill…[/QUOTE]

Nice to see the logo that was used on the steam locomotives, not the logo used on the GN diesel electrics. :cool: