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Cat C18 1015 vs 1150 hp

Discussion in 'Engines' started by bayoubud, Jan 18, 2018.

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  1. captholli, Jan 19, 2018
    #21
    captholli

    captholli Senior Member

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    Huh? Low speed diesels are 600 RPM max, could this possibly what your talking about? I've never encountered any 3500 series motors as such.
    Low speed diesel 600 RPM
    Medium speed diesel 700 t0 1200 RPM
    High speed diesel 1800 and up

    Anyway, In the process of finishing the installation of two C-18's @ 1150 and looking fwd. to the sea trials. This will be my first experience with these 6 bangers.
  2. Capt J, Jan 19, 2018
    #22
    Capt J

    Capt J Senior Member

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    The c18 1150 HP run very good, very torquey. I've run LOTS of them. I just don't see as big of a difference in speed between them and the 1015 HP in the same boats, except 9gph more....... I guess the 3500 series are medium speed then? It's been ages since I've worked on yachts with them, and I wasn't a Captain then, but I thought cruise rpm with them was around 1100 rpms?
  3. captholli, Jan 19, 2018
    #23
    captholli

    captholli Senior Member

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    Yeah, I recon a 3516 would be considered a medium speed diesel with max RPM @ 1800 so my estimate of 7 to 1200 RPM's for medium speed would be off a bit. I'm just used to MWM and Wartsila mediums @ 1200 max. I mentioned the 16v399 or just 399 because it was the precursor to the 3516 just as the 379 was the precursor to the 3412 Cat motors. You mentioned MTU's so maybe the 399 threw u off as to think I was speaking about the MTU 16v- 396 series that your not fond of.
  4. PacBlue, Jan 19, 2018
    #24
    PacBlue

    PacBlue Senior Member

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    Medium speed Diesel engine caps out no greater than 1400 rpm wot.

    1800 rpm wot diesel engines are considered high speed.
  5. captholli, Jan 19, 2018
    #25
    captholli

    captholli Senior Member

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    Thank you, My first thought from memory was closer for Med. speed RPM. I stand corrected. Never thought I'd see a diesel turn 3500 + RPM or so like Yanmars do. I hear that their good motors but have zero experience with them. A lot of people don't realize that Yanmar manufactures commercial ship engines and high HP mediums also @4600 bhp @ 1100 RPM's. Oh well, getting off topic here.
  6. Capt J, Jan 19, 2018
    #26
    Capt J

    Capt J Senior Member

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    Yanmars are good motors, some of the Volvo's also turn 3600 +/- RPMS and cruise around 3000 rpms. They seem to stay together without any issues.
  7. Capt Ralph, Jan 19, 2018
    #27
    Capt Ralph

    Capt Ralph Senior Member

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    Another thought; I learn more here with my friends. Nix that other web site.
    Thx all.
    ,rc
  8. Capt J, Jan 20, 2018
    #28
    Capt J

    Capt J Senior Member

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    They did have some recent c18 acerts popping off (breaking) high pressure fuel lines a year or two ago. I know of it happening on 3 different boats under 100 hours. Have not heard of this happening with the older ones or newer ones.
  9. bayoubud, Jan 23, 2018
    #29
    bayoubud

    bayoubud Senior Member

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    We made a good effort Sunday to run the boat out Hillsboro Inlet...just too sloppy to run beyond 18 kt...very wet... the air vents were open on the forward bridge enclosure and could not close because the zippers had frozen...salted the bridge and my Gal down big time...headed back to the dock without making cruise speed. I did like the engine room better with the C18's...much more room and access than the v12 Cats.
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