Originally Posted by
No Name
This may help some here, parts, resources, etc..
I think the 8V92 is great, while most run from it. Look at boatdiesel.com for info on the 8V92 - they were used in several 50ft class yachts, especially the venerable Hatteras 53 MY that is a massive favorite amongst the cruising couple owner/operators (no capt, no crew). Also dieselpro.com is a great parts resource for the DD's as well as they have hour+ long videos of how to disassemble and rebuild them on the Tube. Know the differences between the 71 and 92 series. The long range cruisers prefer the simplicity of the dry sleeve 71 while the 92 has more displacement & power, it has fragility issues with cavitation in around the sleeves. Most boat engine issues are directly from neglected/differed maintenance, bad house keeping, cheap fluids and parts and owner abuse. While they will rev to 2400rpm, they don't like it and will destroy themselves. They like 1200-1800rpm all day long - and keep it under 2000 whenever possible. Consider that when looking at gearing and speed down the highway. Sportfish boats where the capt's set a 2100-2150 rpm cruise get around 2000 hours out of an engine before a rebuild is required. Long Range Cruisers that loaf their boats around 1400 rpm get 8000+ hours out of the engines. As a rule, any DD at 4500 hours or more is considered timed out and ready for a rebuild - doesn't mean they are shot, but boat value wise the price takes a hit. In the marine world a rebuild is generally $4k/hole (parts & labor) on practically any engine. The DD 2-strokes parts are relatively cheap, but due to them having basically double the parts (total systems) of a 4-stroke electrically controlled engine, you make up the difference in additional labor. DD 2-strokes give the mechanically inclined a ton of options, cheap. Swapping out injectors, adjusting timing, etc... All things to make your DD go from mild to wild. Regardless all DD 2-strokes that are E rated (high performance boats, yachts, patrol boats, etc.) are essentially 1hp per 1 cu in. so an 8V92 E rated marine DD would be between 700 & 750hp. The commercial continuous duty ratings will be down in the 400hp range and governed to 1800rpm. There is the secret with the ratings, they do reduce injector size but mainly reduce the rpm from 2400 (E), to 2300, to 2100, to 1900 to 1800 (A).
Usually truck engines are detuned significantly because they A: do not have an endless supply of cooling capacity from the ocean. B: are operated in constant start/stop/load/rest environment on the hwy, where a boat simply sets the throttles with a relatively constant load condition. Most good capts run their engines based upon load percentage vs RPM/speed. Know what the BSFC of your engine is and try to run right at that RPM - the engine will last forever, produce the most tq/hp per rpm and yield the best fuel economy (it's usually right where the Hp and Tq curves intersect. The DDs produce gobs of Tq down low and drops off sharply as RPM exceeds.
As mentioned in precious posts, we came from the boating world, unless you can't tell. To 2nd the post above, no engine should leak. Some engines have design issues that get improved with each version to mitigate leak prone areas. The evolution of the Cat 3406 A, B, C, (no D) E models all had changes to the head gasket/spacer plate design as well as the peanut cover on the front. I would definitely watch for smoking and check oil level daily - with the supercharger these engines can produce enough blow by on a severely worn engine to start eating themselves/running on the crankcase oil vs diesel from the injectors - one main reason they have manual flapper valves to close the air intake.
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