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  1. #1

    8V71ti's fuel consumption

    I take delivery of my new (to me) 58' YF with 8v71 ti's on Sunday. Does anyone have any fuel consumption information or know a site which might provide me with some general information?

  2. #2

    Re: 8V71ti's fuel consumption

    should be about 10gph at 9 knots or 35gph at 16knots.

  3. #3

    Re: 8V71ti's fuel consumption

    Real basic numbers .75 x horsepower = burn at max cruise
    .25 x horsepower for displacement speed
    Works for most boats. Double the speed triple the burn.

  4. #4

    Re: 8V71ti's fuel consumption

    For planning, I think it's best to think of it in gal per mile. The hull speed of your boat is about 9.8 knots. That's the most efficient speed for your boat. You'll get a little better than 1 gal per nautical mile at hull speed. But that's really slow. If your hull, engines, props, etc. are in good shape, your boat will plane by taking it up to 2300 RPM until it planes and then backing down to 2000 or 2050 (but watch the engine temps to stay below 190 degrees). Planing, you can probably do 15 knots while burning 2 gal per NM. So, 50% faster is twice the fuel per nautical mile.

    Doug Shuman
    1978 53MY (8V71TI's)

  5. #5

    Re: 8V71ti's fuel consumption

    Thank you all very much.

  6. #6

    Re: 8V71ti's fuel consumption

    My experience is bit different. I have a '71 58 YF with the 8V71TIs.

    To be honest, I am not sure I actually ever get the boat fully on plane. At my usual cruise of 1500 RPM, I get between 10.5 and 11 knots out of her. I burn about 15 gallons per hour at that speed (both engines combined).

    If I increase the engine speed, the boat speed increases linearly up to a maximum of about 15 knots (at most) with the engines between 2150 and 2200. My engines never get up to 2300 - which almost certainly means I am over propped. Of course, while the engine speed and boat speed change in a linerar relationship, the fuel consumption, alas, does not :-)

    I can send you the engine speed <-> boat speed numbers if you like.

    I will be extremely interested in the experience you have with speed and fuel consumption to compare against mine. I posted a similar request to yours in this list many months back and, while I got some excellent responses, no one with a 58 YF was able to tell me their actual experience.

    So do let us (or me, if no one else is interested) know.

    Take care - Murray (doing some consulting in Barcelona - but looking forward to two weeks on the boat when I return).
    --
    Murray G.
    Vancouver, Canada
    1971 58 YF

  7. #7

    Re: 8V71ti's fuel consumption

    Does anyone have the same kind of estimates for a 43C with 6V92ti's.

    Thanks,
    Gene

  8. #8

    Re: 8V71ti's fuel consumption

    Does anyone have the same kind of estimates for a 43C with 6V92ti's. 19 knots @ 1950 turns

    Thanks,
    Gene

  9. Re: 8V71ti's fuel consumption

    45C with 6V92TA 500s turns 18 kts @ 1900 RPM burning about 36gph (combined)

    Estimated off long runs, no flowscans.

    On the pins I can do 22/23 with my usual load, but I never run over 2000 (which is in the 19ish range) Anything more than that requires 30+kts of wind at my back

    She saw 25kts once - at sea trial, with about a gallon of fuel, no water, no waste, and three guys on board.....

  10. #10

    Re: 8V71ti's fuel consumption

    Murray,

    Either over-propped or fouled bottom, or wrong injectors, or, or..........

    Your engine ID plates will show the max RPMs for which your specific engines are rated. You should be able to get there at no load and close to it with a good load. Karl (Genesis) has opined numerous times in previous threads about overloading engines, high exhaust temps, etc.

    You'll know when she actually gets up on plane because the bow comes way down to level attitude again. At all speeds before that, the more power you apply, the higher the bow goes and you're pushing a mountain of water in front of you and digging a bigger hole behind you.

    Doug Shuman

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