Bizarre Powerplants

There’s No Replacement For Displacement

So let’s say you just built a supertanker, or maybe a giant cruise ship. You need to power it somehow. You start doing the calculations on how much power you need and you think to yourself, “Crap. I would need 15367 LS1 engines to make the torque I need to move this through the water. What am I to do?!”

Well, you start off by ripping everything off the hull so you can drop one of these bad boys in. Behold, the Wärtsilä-Sulzer RTA96-C.

In 2006, as a response to the need for more fuel efficient maritime diesels for very large ships, Wärtsilä built the RTA96-C. It is a two stroke diesel capable of up to 108,920 hp and 5,608,312 lb/ft at 102 rpm in its largest (14-cylinder) configuration. If you don’t need that much power, or you just don’t have enough space, you can get 6, 8, 10 and 12 cylinder versions. All versions make 7780 hp out of each 1820-liter cylinder.

In the 14-cylinder version, the engine alone weighs 2300 tons and stretches 89 feet stem to stern and rises 44 feet from the bottom of the crankcase. So, yeah, you’re not just going to carry it down the stairs into the engine room.

It’s a big, powerful engine. It’s also incredibly efficient. The Brake Specific Fuel Consumption (fuel consumed per horsepower) at maximum power is 0.278 lb/hp/hr, and at its most efficient setting it is 0.260 lb/hp/hr. That’s incredible! A typical automotive engine is 0.40 to 0.60 lb/hp/hr. Even still, just due to its enormous size, the 14-cylinder version consumes 1660 gallons of heavy fuel oil per hour. So, in a one week transit it burns through 278,880 gallons. Keep that gas card handy.

The engine is very similar to automotive engines, with one big difference. Rather than the connecting rods running between the crank and the cylinder, the RTA96-C connects the con rods to a crosshead that drives the piston shaft. This allows the piston shaft to move straight up and down, reducing forces on the piston head and seals the combustion oil from the crankcase oil keeping the crankcase oil free of combustion particulates.

So, there you go. One big ass engine for some big ass ships.

[Image Credits: Wärtsilä]

  • pj134

    Normally I would say in response to the title, "UHUH! FORCED INDUCTION IS!!!!!"

    Doesn't quite work here.

  • The Professor

    Great post! You know, every time I make a post about one of those huge machine tools, I think about these engines. I'd love to see the tooling used to make these giants.
    And 5,608,312 lb/ft of torque? Boggle….

  • Somewhere a Honda Civic owner is saying, "SWAP!"

    • PowerTryp

      Drop this on a civic to un pimp ze auto.

  • skitter

    Thanks for using BSFC for actual apples-to-apples comparisons of engines.

    • You're quite welcome. It doesn't make sense to compare the fuel consumption on this to an LS1. It would just be…ridiculous.

  • I can't decide if I'm more interested by the giant engine or the heavy duty MB tractor (note the box behind the cab: that's the cooling system for the torque converter) and trailer…

  • On the manufacturer site, one can download a zip file full of technical drawings! http://www.wartsila.com/en/engines/low-speed-engi
    I will have to try loading the 3D files into my CAD program at home…

  • The Professor

    I wonder what they use as a starter motor? The engine out of a D-11 Cat? Would that be big enough?

    • Regrettably it's probably not a scaled-up version of the Inter Berline's gyrostarter. The demonstration starts after about ten seconds:

      [youtube zlZMeIO4Vao http://www.youtube.com/watch?v=zlZMeIO4Vao youtube]

      • Tiller188

        Was that…an inertial starter on a microcar? That's awesome! (Although, via Pavlovian conditioning I was expecting a rather beefier sound…say, a P&W radial…when the engine kicked over…)

    • highmileage_v1

      That puzzles me as well. Compressed air? A smaller diesel? Inquiring minds need to know!

    • They might never shut it down…just a thought.

      • The Professor

        Yeah, install that sucker while it's running! I'll bet that the crane operator would be thrilled.

        • Well…after the initial start using a half-ton of dynamite in each cylinder, that is.

    • skitter

      They get a thousand Viking rowers and push-start it.

      • The Professor

        I want to be the guy inside that lets out the clutch.

      • PowerTryp

        I've got good news and bad news first, good news! Every one gets double rations! umm… the bad news is we have to pull start the RTA96-C.

    • P161911

      A pull cord and a big crane?

    • 1000 guys and a pull cord?

      • skitter

        NOT.
        IT.

        • New Lemons penalty?

          • skitter

            The terrifying no-compression-release pull-start of terror.

  • I'm most curious about the manufacturing tolerances on a motor like this.

    What's the +/- on the bores or bearing caps?

    • As far as that goes, does anyone sell spools of Plastigauge by the yard?

      • The Professor

        Ha! I had that same thought when I was looking at those bearings.

  • One more question: how do those large ships reverse? Is there some kind of gear box between the engine and the propeller (unlikely), can the engine be reversed or does the propeller use adjustable blades?

    • The Professor

      According to this article – http://www.dieselduck.ca/machine/02%20propulsion/
      The engine is run in reverse. I would have thought doing something like that would be horribly difficult, but evidently that's not the case.

      • pj134

        … I wonder if they use a Jake brake on it… and what that would sound like…

        • The Professor

          I don't know how applicable it would be for a ships engine, but if it does, it probably sounds like Cerberus growling.

          • B72

            A Jake Brake's purpose is to absorb power over relatively long periods, so a boat or ships engine has no need for one. I belIeve they have a brake on the propeller shaft for times when they don't want the whole thing turning.

            As an aside, Clessie Cummins was retired when he developed the Jake Brake. The only engine he had to play with was on his boat. So when the idea was pitched to what was then the Jacobs Chuck Company, they got a demonstration on a boat motor, and all it could do was spin down from max RPM a little faster than normal.

          • pj134

            I don't know how long a period you mean, but truckers in my area use it whenever the opportunity arises. Redlight? Jake brake. Don't like the car next to you? Jake brake. Trying to accelerate? Jake brake. Every chance they get they use the damn thing.

          • B72

            Back when I worked for Jacobs, Eaton inquired as to whether they could use the Jake Brake to speed up shifting for their “Autoshift” transmission product. After considering it, engineering came back and said that the number of cycles that would generate was outside of the design parameters.Lot's of folks “Jake Shift”, but the company didn't recommend it, at least when I was there.

          • The Professor

            That's what I was thinking. What made me wonder is when they change the engine over from running in forward to running in reverse, and if some sort of compression release mechanism was used then. I just don't understand how you would get a big engine like that to stop, then run backwards.
            Nice anecdote about the Jacobs company. I would have thought that a Jake Brake was a little out of their bailiwick.

          • B72

            Now you have me wondering. If it's a 2 stroke, I'm not sure it knows which way it's turning. Cut the fuel and turn on theshaft brake and the engine will stop. It seems that with a starter that could turn either direction, they could make it work. I wonder what that starter looks like.

          • The Professor

            Yeah, we were trying to figure that out earlier in the thread. The general consensus was something involving a big pull rope. I'm dubious myself, but still curious about the actual mechanism(s).

          • B72

            It looks like they put compressed air into the combustion chambers to move the pistons and get the engine turning, then turn on the fuel once it hits minimum operating RPM. http://www.brighthub.com/engineering/marine/articles/41852.aspxThat is a far less fun image than a whole lot of guys on a really long pull cord.

          • The Professor

            Dang! I wanted to dump the clutch on a push start…..

    • highmileage_v1

      Warships have variable pitch props. Apparently a "crash stop" is an event to be remembered.

  • Number_Six

    I wonder why it's two-stroke. I can't imagine this motor doing the ol' ring-a-ding-ding…

    • tonyola

      The reason for two-stroke is that type of engine produces around twice the specific power of a four-stroke. Also, a two-stroke diesel is just as clean burning as a four-stroke since the only thing that undergoes compression is air. http://auto.howstuffworks.com/diesel-two-stroke1….

      • The Professor

        Hmm. I'd never really paid any attention to two-stroke diesels before, I'm not really a fan of diesels, but that looks like an excellent process for large scale engines, like the monster up top. I'm learning all sorts of things today. I still spilled my damned coffee again though.

      • Number_Six

        Ah, now it makes sense!

  • Number_Six

    100 points!! Woo!!

    /the most exciting thing to happen this month
    /get a life
    /100 points!

    • P161911

      Only 2 more to go until you reach AWESOME!

      • Number_Six

        Crap, I'm not awesome yet? Why did I get out of bed today?

    • Hey! You're in the exclusive Century Club! That means you get to find out what's behind the blue door. Unfortunately, it's just Mitch wearing nothing but a moose hat and bunny slippers. But, good news! If you make it across the room to the red door, you get all the scotch and cigars that you can handle!

      • Please tell me The Professor doesn't have a doll/figure/statuette of that on standby for the next scavenger hunt.

        • The Professor

          Pthhbbbbt! to you too. No, no more girls. The gag is over.

          • Hey, at least it put you over the top. You're welcome.

            Also, I had no idea Mitch was a girl.

          • The Professor

            I'll bet that he's surprised too.

          • The Professor

            Oh, and thanks. I wasn't paying attention.

          • The Professor

            Ok, I'll bite: why do you think Mitch is a girl?

          • I asked for reassurance that you weren't preparing a photo of your 'figure' of Mitch attired as described by engineerd, above, and you responded by saying "No, no more girls." What else was I to conclude?

            No, on second thought, perhaps I don't want to know what else I should have inferred from that exchange.

          • The Professor

            You, sir, are a goof.

            /You made me laugh with that one. Goof.

    • The Professor

      Congrats. It's about bloody time, too.

      • Hey, you're here too! Of course, since you're on staff you get a kiss and a bear hug from Techie.

        • The Professor

          Oh joy. I'll give Techie a break, I'm sure that he doesn't want old-man-smell all over him.
          Yeah, it clicked over sometime between 12:30 and 1:00. I was busy being insulted by mdharrell (again) and didn't notice at first. It seems that I've gotten a bit garrulous.

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