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8v92 turbo 720HP longevity

Discussion in 'Engines' started by Seafarer1, May 21, 2015.

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  1. Seafarer1, May 21, 2015
    #1
    Seafarer1

    Seafarer1 New Member

    Joined:
    Feb 19, 2015
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    Location:
    Michigan / North Carolina /Fla
    Hi guys,
    I have a question about 8v92 turbo 720HP engines.
    Say these engines are in a well cared for and maintained 46' - 52' Hatteras Sportfishing vessel.
    The engines have approx. 2400 hrs on them. Some at cruise and some at hull speed and different trolling speeds.
    These engines should be able to reach 3000 hrs or more before having to do a MOH.
    The question:
    What can we do to extend the operating hours on these engines instead of a total rebuild.
    This vessel will be used in the sportfishing charter industry.
  2. Bamboo, May 21, 2015
    #2
    Bamboo

    Bamboo Senior Member

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    Palm Beach, FL
    I have a set of 16-92's 1450 HP so some of my experience may help. Make sure your water pumps have clean screens under the boat or a clean filter inside the ER if that is where it is. Check the impellers at least yearly and buy an impeller puller. If one blade is cracked then change the impeller- you don't want to be taking the system apart to find the broken off blades downstream blocking a cooler. Make sure your heat exchangers are clean; the main units and the PS and fuel coolers. Make sure your charge air coolers are clean. Don't fall behind on sacrificial zinc changes. Change the racor filters and secondaries on schedule. Flush and replace the coolant every three years. Make sure your props are matched to the boat so you reach your full load rpms; you don't want to over load your engines and have excess black smoke at speed. Keep the bottom clean. Install a set of block heaters (coolant) and keep them on all the time. Change the oil between 100/150 hours, or better yet install a set of aftermarket bypass (3 micron) filters. I have 3000 hours SMOH on one main and 1000 SMOH on the other and they start right up with no smoke and run very smoothly. I cruise between 1700-1850 rpm and only make top speed runs when I know the bottom and intake screens are clean. I'm confident with a careful eye and attending to items before they are an issue I'll get at least 5000 hours before any type of overhaul is warranted.
  3. RT46, May 21, 2015
    #3
    RT46

    RT46 Senior Member

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    Bamboo is on point....

    92 series have wet liners which require special attention to the cooling system and PH
  4. Seafarer1, May 21, 2015
    #4
    Seafarer1

    Seafarer1 New Member

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  5. Seafarer1, May 21, 2015
    #5
    Seafarer1

    Seafarer1 New Member

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    Bamboo, I really appreciate the time you took to let us all know this very important information.
    It all boils down to don't run them hard, and do all the maintenance required, when it's required.
    You don't have to necessarily baby those engines, just don't dog them, then we should get some longevity from them.
    I see you are down at Sailfish Marina Palm Beach.
    You said you leave the block heaters on all the time. Do you need them in that warm of a climate?
    I know that they make it easier starting on the engines.
    What if the sellers don't really have any logs of required mantenance, just their word or their mechanics say.
    You really have to take that with a grain of salt.
    Thanks again.
  6. Bamboo, May 21, 2015
    #6
    Bamboo

    Bamboo Senior Member

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    There's a Bertram across the pier from me with 8-92's. When they start them up it's thick smoke city for a good three minutes. Everyone in the marina and restaurant sees it. I start my engines and there is a slight wisp for a few seconds; plus I don't need to warm them up (as much).

    Check the zincs yourself if you are buying the boat- if they are all good either they just changed them or they are on top of it. Look at the oil level; is it in range? Check the coolant level- and color. It ought to be pinkish. Check the engine bed- does it have oil leaks? If it doesn't then the engine is out of oil :)

    You are right- don't run them hard and do all the maintenance. Other captain may chime in with other advice, but that's how I care for my engines and they treat me very well. I have non DDEC versions and love them.
    Last edited: May 21, 2015
  7. Capt Ralph, May 21, 2015
    #7
    Capt Ralph

    Capt Ralph Senior Member

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    92s are not a forgiving engine. I do believe that Murphy designed them.
    Get a real in depth engine survey. If no problems then; Baby the heck out of them. NO corners cut. Never let them get close to over heating. Always fresh impellers, zincs, oil and strainer inspections.
    At 1800/1900 rpm, they can run forever (lots of fuel).
    If your not a good DIYr, find a good DDC manager to keep all up to snuff.

    I'm assuming Alison clutches (MH). Get a in depth survey there also.

    Was this the boat from Vero Beach?

    Charter work?? You may want to consider a larger cut to the boat than the norm (smaller in your pocket).
    Fuel and maintenance (even planned) will demand it.

    ,rc
  8. Capt J, May 23, 2015
    #8
    Capt J

    Capt J Senior Member

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    I would say 3000 hours between majors on those, sometimes less. Aside from changing the coolant (additive) every 2 years. MAKE sure the boat is not overpropped. 8v92's live a very short life is they don't turn up to top rpm at WOT with the boat loaded, even 30-50rpms over is good.

    There are two schools a thought at running them. Some say cruise them at 1850rpms (granted most of these people don't realize the boat is overpropped by 100 rpms either. The other more modern school of thought is make sure they're propped to achieve RPMS to 50rpms over and run them harder such as 1950-2000 rpms where the boat is fully on plane and they sound like they're running easy and maintaining a steady speed over ground (keeping EGT at 850F or below) and they run cleaner and the liners don't get washed out by the usually too big injectors. We ran a 1987 63' Ocean this way (towing a 35' Marlago) a lot of time and got an honest 6500 hours on a set of 12v92's. I've never seen it on the boats I've seen run easy (1850), and 12v92's I see go 1000 hours between majors on those. One 58' Striker 1988 I managed had 8 sets of majors by 2004 with 12v92's and was always run 1850-1900 rpms. Problem was at those rpm's it wallowed between 17.5-21 knots as it fell onto and off of a full plane......at 1950-2000 rpms and ran a solid 22.5 knots and stayed there.......92's don't like changing load factors and being loaded and unloaded (varying cruise speed over ground). They seem to do well in boats that they cruise it at 25-30 knots for the reason sea state has less of an effect on cruise speed.

    I much prefer 71's and agree they're more forgiving.