Experience with 8V-92 Detroit diesels

[spindrift]

Folks:

Is anyone running now or in the past Hatts with 8V-92 engines? I am looking at a late 80s Hatt that has these and have heard via Yacht Club and boatyard grapevine mixed reviews of these engines.

I am looking at a MY not a sportfish and thus the engines are not that juiced up (still rated at 720 hp each). I would appreciate feedback on these engines and any stats on fuel burn if you have them.

Thanks in advance.

Spin

 

[JLR]

I have 8 92's and have been running them for the last 13 years or so. I like the engines but mine are only rated at 650 hp. 720 is getting up there for these engines. I needed to major both of mine at about 2,000 hours which I understand is fairly common. My fuel burn is 50 gph at 175 off of the pins and 25 gph at 1500 rpms. This information is from a 56 MY.

 

[spindrift]

Dear JLR

Thank you for feedback. What type of speed are you achieving at those two RPM settings.

Thanks
Spin

 

[Genesis]

Biggest issue with the 8v92s is the turbos -- the design is weak in the housing section and you need to make sure the exhaust is properly-supported so it doesn't load the turbo housings. If you don't the exhaust-side seals will get broken and then you get soot ingestion into the engines, which is extremely damaging in a big hurry.

Other than that the usual "gotcha" for high-horsepower Detroits is overheating. Diesels in general are VERY intolerant of overheats and marine DD turbo engines are marginal in their cooling capacity. If you're in a year-round boating area (no-freeze conditions) consider running distilled water + DD-approved inhibitors instead of coolant as that will give you 7-10% more heat transport capacity, which is a big improvement. This is a DD-approved option; it's not "back yard mechanic" stuff. Keep the coolers clean. Do not let the engines go over 185F -- period -- if you start to see temperature creep problems find out what's going on and FIX IT IMMEDIATELY.

And as with all engines, make sure you're not overloaded (that you can turn up 2350 at WOT, etc.)

I like DDs in general but the 8vs at 720HP are pretty high-strung and as such very intolerant of anything being out of sorts.

 

[spindrift]

Genesis

Thanks for the feedback. My inclination is to find a good boat (and despite all logic) re-power. I have already spoken to a friend who is a CAT dealer (who by the way says from a cost sense not to repower) and have a general number for going with C 15 Acert engines.

The end result if handled by a top yard should be very good.. expensive but much less than buying a new boat.

Spin

 

[JLR]

At those rpms, I cruise at 15.5-16 kts and at 1500 rpms I am doing about 10 kts.

 

[jim rosenthal]

As you say, from the economic point of view this makes no sense at all. From the boating point of view, it makes eminent sense- the boat will go faster, use less fuel, be easier to service, and run with less noise. You might look at M11s as well, and compare prices.

 

[Genesis]

I'm a Cummins fan all things being equal, but the newer CATs are nice too. Much depends on local support in your area in terms of warranty and such.

The newer engines make absolutely zero economic sense when looking analytically at the issue (repowering) for a recreational user, even if you use the boat a lot, but in terms of social issues (noise, smoke, etc) and personal enjoyment it may still make sense to do it if you intend to keep the boat. Just beware that if/when you go to sell while the repower will make a difference in value you won't recover anywhere near the fraction of the cost you probably think you will.

I looked at putting M11s in Gigabite when I owned her and decided against it. Had fuel not gone nuts and the marinas in the area not become too hostile for me to put up with their crap any more I'd probably still own the boat and would have probably done it. As it sits I'm glad I didn't but only because I sold and while it would have made the boat more desirable (by a lot!) on the market it wouldn't have resulted in me recovering enough of the cost to be worthwhile.

 

[Bill Root]

I have the 735HP 8V92's in BUFFALO GAL. Like you I had heard some negative things about these engines, particularly the high horsepower versions, so I commissioned a complete survey of both engines before buying the boat.

The engines had approxinmately 2300 hours on them at survey. The owner I was buying the boat from had run the boat very easy and had performed excellent maintenance, however there were no records prior to his purchase of the boat with approximately 1300 hours on the engines. The survey came back very strong. In fact, there was very little wear on the cyslinder liners or rings. I think as others have said here that the reliability of these engines is almost entirely dependent upon how the boat was run and what kind of maintenance schedule was performed. A quality survey by a qualified diesel engine surveyor is, in my opinion, a must. The couple thousand dollars you will spend on the survey is worth every penny.

Most of my cruising is on the AICW and inland rivers, so I am running at 9-10 knots 90% of the time. I do try to find a way to push it up to 2300 for a few minutes every day or so to get the turbos going and clear them out. When I do that, I generally get a pretty good puff of smoke out the exhaust for the first few seconds, then the exhaust clears up. I have had to re-build one turbo
that was "slobbering" (nice diesel term), but other than that only routine maintenance in the 300 hours we have put on the engines.

I don't see where you specified what boat you're looking at. BUFFALO GAL is the wide body 54MY. At 1250 RPM's she does approximately 9 knots and burns about 1.00 gal/statute mile. I haven't run enough at 2300 to know the exact burn, but she does manage 19 knots at that RPM and I expect the consumption to be about 3 gal/statute mile, not bad for an 80,000lb. boat.

At the end of the day, I wouldn't shy away from a boat I liked just because it has these engines. How the engines were run and what kind of maintenance they received is the most reliable indicator of how much life you can expect from them. A good engine surveyor can tell you that.

 

[captainwjm]

My experience is almost exactly the same as Bill's.

 

[GJH]

Ditto, but I have 650hp's. I run the boat exactly like Bill.

 

[cholly123]

Had 8V/92's in my 1990 63' Viking MY. Had 3 rebuilds (2 on one engine, 1 on the other) within the 5-year extended warranty . 1 rebuild (at 300 hours) was caused by the factory seating an oil pump bolt in silicone!! Total hours when I sold in 1997 about 3000. Best service was from Galati Marine on Anna Maria Island, he had more influence with Detroit than anybody else I knew, even out of warranty repairs.

I always felt that the 12/92 option would have been better for that weight.

Usually running 2100 rpm up and down the Mississippi and other rivers from Minneapolis to Florida I would experience about 55 gph. Carried almost 1500 gallons, so could run about 3 days between fills. Viking also offered the MANs but they had a spotty reliability and service record in those days.

Charlie Berry

 

[GJH]

One thing I noticed when we were shopping is that once the MYs got over 58 feet, Hatteras put in 12v71's, also rated at 650. For instance, the 61CPMY which is my boat with a cockpit added, had 650hp 12-71's . Ditto the 61MY. Torque is king (?)

 

[Genesis]

The 12-71s have over 100cid of displacement on the 8v92s and for equivalent power output are less-stressed. They're also materially more thirsty.

 

[spindrift]

Hi Bill

I am sorry for being late in thanking you and the rest of our colleagues for your wise advice. The Admiral is finally given my the thumbs up to begin the process now that I have committed to pull the trigger on the land for her new beach house. The boat is going to cost me a bundle (waterfront property is sure expensive) but it sure is cheaper than a divorce.

Spin