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Old 04-21-2020, 09:24 AM   #21
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I am with Rufus above- keep the DD 8.2s. In addition to the injector rack problem he mentioned and the need to swop out the head bolts for better ones, there is also a fix to the coolant system that includes a vent from the aft cylinders to avoid a pocket of air building up and blocking coolant flow.

If you do these mods, I don't see why those engines can't keep producing 200 hp each for a long, long time.

Pretty boat though. Keep your money for new engines and spend it on keeping the cosmetics sparkling.

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Old 04-21-2020, 09:29 AM   #22
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If you do these mods, I don't see why those engines can't keep producing 200 hp each for a long, long time.

Even better than that, I'm under the impression from what FF posted and the other link that was given that a 20 kt cruise is about 200-ish hp total, not per engine. Based on the numbers for the Renault powered boat, it was doing 27 kts at less than WOT with 420 total HP. So cruising at 20 kts is going to be very easy on the 8.2s with only somewhere in the 100 - 120 hp per engine ballpark for continuous power demand.
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Old 04-21-2020, 01:47 PM   #23
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The Ford 7.3 turbo diesel (designed & built by International) was marinized and there are rebuilt engines out there. But it has several electronic sensors that are a pain. Marine accessories like exhaust manifold could be hard to come by. Newer Ford diesels are nothing but trouble. Especially the 6.0.

The Dodge diesel would be too tall. No idea on the GM.
If cost is an issue, there are marine diesels from China. Some Cummings are made there. And parts of many other diesels are made there.
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Old 04-21-2020, 02:50 PM   #24
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"Changing from D.D.s to almost any other brand will probably mean changing the "V" drives as well as everything else including mounts, shafts, transmissions"

Now you have me stumped . The V drives I have seen were mounted to hull stringers to take the thrust and the engine was a distance away with a short shaft to the V drive.

I would hope to keep all that intact and simply have the machine shop create a plate to the DD tranny. A new shaft is no big deal. Re use filters and exhaust .I don't suffer Bestitis (any more).

The more modern engine would be almost the same power , so the V drives and tranny should be OK.

New motor mounts is also no big deal , controls should come with the engine , if not Murphy Gauges would monitor the engines.

The biggest problem I see is all the new engines have electronic injection , nice and quiet if they do it right , but perhaps Sea Tow in lightning capital FL.

All the more modern engines spin at a higher RPM , which might demand a different tranny , or a different set of props.

A marine exhaust manifold for a converted engine could be avoided with a dry stack exhaust.

Yes , unquestionably keeping the stock DD 's would be best , and a 10-12K cruise would be just fine with us .

I'm trying to figure worst case ,just in case, as I don't want to end up too broke.
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Old 04-21-2020, 03:11 PM   #25
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If you're talking new.. Well you shouldn't be talking new engines.

You can buy modern engines used, freshen them up before install and save yourself tons of money. Big diesels don't trade hands often on craigslist and other regular sources. My advice would be be calling places in Ft Lauderdale once you decide on a engine. They are the yacht capital of the world and always have lightly used engines laying around.

You can get more HP in a much smaller package but i'm not sure how that'd work out for you. The 5.9 Cummins QSB engines are putting out up to 480hp. I occasionally see them for 10k for a pair but typical is about 20k and new is about 20k per engine.
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Old 04-21-2020, 03:13 PM   #26
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If the transmissions are an integrated trans / v-drive there might be fitment issues. But I don't think it would be anything un-solvable.

It looks like the 8.2s turn anywhere from 2800 to 3200 RPM depending on rating, so plenty of other engines would be in the same ballpark. And there are enough marinized diesels out there that at least one of them of sufficient power will fit into the holes the 8.2s are in now. Looks like the 8.2s are 31.4 inches tall, so depending on how much space you've got above them, you likely have choices. A QSB 5.9 is 33.8 inches tall, for example, so only an extra 2.5 inches. The newer Yanmar V8 diesels are just over 30 inches tall, so they'd definitely fit.

Looks like the Detroits are just over 1500 lbs, so the QSB or Yanmars would be lighter.

From what I can find, the 8.2s in marine form were rated anywhere from 130 to 300hp, depending on who marinized them and turbo or not. I'm seeing mentions of Detroit calling the turbo versions continuous rated at 160 or 200hp at 2800 RPM. NA continuous ratings were 130, 145, or 160hp at 2800. So I wouldn't worry about cruising at 20 kts with the 8.2s if the total power demand is only in the 110hp per engine ballpark at that speed. Doing that for days on end wouldn't be pushing them too hard, IMO. I'd personally consider that to be standard fast cruise with the ability to sprint a bit faster.
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Old 04-21-2020, 03:24 PM   #27
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Dear F.F.

If you are looking for advice here it is. Don't do it!

If you have never attempted it don't say something is simple. Motor Mounts, simple? (Not) , Dry exhaust, simple? (Not) Wiring, gauges, fuel delivery, adapter plates, longer or shorter shafts, etc, Simple? (NO, NO, NO)

Have fun, Good Luck, you will need it

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Old 04-21-2020, 04:33 PM   #28
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FF ran a marina for many years.
He is very savy. Motor mounts would be easy for one of his knowledge.
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Old 04-21-2020, 05:58 PM   #29
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If the 8.2 engines check out on survey, they will run for decades at low to medium power levels. Just pay close attention to the cooling system. The ones in our OA have a factory installed coolant temperature sensor on the engine that sounds an alarm at 205 F. I added thermocouples/alarms after the exhaust risers. Also, water temperature at high power settings dropped almost 10*F after I cleaned out the calcium deposits in the transmission coolers.

Back in 2005 Johnson and Towers sent me an excellent prop chart for the engines in our boat. Matched up very closely to real world values when I checked them against actuals. FF, if J&T did the marinization on the subject boat, you might give them a call to see if they have one for a boat like the one you're considering. I spoke with one of the engineers who actually worked on the marinization/certification of the 8.2 back in the day. His view was that it was a marginal truck engine, but made a great marine conversion. A "gem" to use his word. By the way, the engine uses the truck/street governor...takes a little familiarization, but fine in actual use.
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Old 04-21-2020, 06:13 PM   #30
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Swapping out a V drive boat is a can of worms. A set of QSB’s [ that would be a good choice} will cost 100k. 70 k for factory rebuilds. Now the fun starts, gear engine beds, props, wiring, check tanks while you are there, paint bilge, change out all hose and thru hulls. Here we go. $150 easy
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Old 04-21-2020, 06:51 PM   #31
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Modern parts in an 8.2 rebuild could be the answer if needed?


This links to a site that might be interesting:
(Filter for BS like any site)


https://everythingaboutboats.org/detroit-diesel-8-2/
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Old 04-21-2020, 07:02 PM   #32
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I sure didn't mean to insult F.F.s ability or knowledge. If he ran a marina for a number of years he knows more than I do.

I wonder if more knowledge and experience would make someone more or less anxious to tackle a project of this magnitude.

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Old 04-22-2020, 06:05 AM   #33
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The boat is up in Oxford MD and is currently having new cylinders installed in one engine. Have no reason for the overhaul, or weather the crank will be done or the head bolts diameter increased .OR the condition of the other engine.

When ever we are permitted to return to our second home (a small cottage) in CT we hope to visit the yard on the way and find out what we can.

I am familiar with some of the used engine sources in the Miami area , some are rattle can specialists.

Any used engines would have a trip to a dyno before purchasing. If there out its not very expensive .
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Old 04-22-2020, 09:22 AM   #34
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The engine power jumps were done with different injector sizes. (Except the 300, which was also intercooled). The 220 was common in trucks, busses and industrial pump applications. I'd keep an eye on Ebay, Craidslist, car-parts.com, etc. I spotted a 400 hour 220HP water pump engine from a small town fire department last year. Easy to swap over the injectors and bolt-on marine stuff.
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Old 04-22-2020, 10:12 AM   #35
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"I'd keep an eye on Ebay, Craidslist, car-parts.com, etc. I spotted a 400 hour 220HP water pump engine from a small town fire department last year. Easy to swap over the injectors and bolt-on marine stuff."

IF we get her that will plan A , along with modest throttle settings.

It would be great if she could handle that 18K cruise tho , would make more lay days and keep "she who must be obeyed" happy.
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Old 04-22-2020, 10:13 AM   #36
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"I'd keep an eye on Ebay, Craidslist, car-parts.com, etc. I spotted a 400 hour 220HP water pump engine from a small town fire department last year. Easy to swap over the injectors and bolt-on marine stuff."


IF we get her that will plan A , along with modest throttle settings.


It would be great if she could handle that 18K cruise , would make more lay days and keep "she who must be obeyed" happy.

To clarify on the power requirements you mentioned in the first post, I'm gather than the 220hp at 20 kts was 220hp total, not per engine, correct? If so, running the engines at 1/2 power shouldn't stress them much at all. Even a typical gasser would live a long life at that relative power output.
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Old 04-22-2020, 10:30 AM   #37
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Nice looking cruiser:
https://www.dimillosyachtsales.com/b...-express/2848/
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Old 04-27-2020, 02:14 PM   #38
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Hyundai Seasall 270S

http://www.trucktrend.com/features/1801-hyundai-seasall-s270-advanced-ultralight-marine-v-6
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Old 04-29-2020, 03:42 PM   #39
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Replacement diesel

Quote:
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Looking at a boat with a pair of DD 8.2 , not a good engine from years ago.

The engines are under the aft cockpit floor (V drive) SO should be pretty easy to swop.

Wondering if any modern medium truck diesels have been marinized ?

A pair of rebuilt 500ci Cummins would be first choice , but the height of the inline engines would require the cockpit to be rebuilt UGH!

The boat requires 220 shaft hp @20K ,, claimed burn 10.5 gph

27k is claimed @ 18.8gph , and only 72 hp for 10k, burn 4gph.

The 27K @ 18.8 gph might be about 10gph per engine which should be reasonable for a modern medium duty engine to produce.

10 to 15K would be sweet spot for our style of cruising , as long as the engine would accept our 10-12 hour days.

Any suggestions on modern engines of a V config?


Here's my suggestion: Don't buy a boat with a V drive configuration.
The reason people belong to Forums of any ilk is to talk, discuss, get varying opinions etc. Mine is run like hell from a V Drive. There are too many other boats out there. Like I said, "Just my opinion".
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Old 04-29-2020, 03:58 PM   #40
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Replacement diesel

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Gas engines would be OK with me the boat is an inshore boat not a voyager so less range would not be a big deal.

The hassle is gas engines require spark proof everything in the engine space , haven't itemized the list to guesstimate a cost. Yet,

The best suggestion so far would seem to be the Mercruiser 7.3L diesel, if there still made .

The boat is a 44 ft Midnight Lace .

My dream boat for 20 years , so if not now when?

The current plan would be to operate the boat at modest speeds and do next to nothing except plenty of PM .

I am looking for a plan B should the engines die early in our ownership.

To a great extent the boat would replace our Sprinter class C to snowbird every year from CT to Fl and back in the spring.
If anyone shows you a boat with a gas V8, run. If it has 2 V8s, run twice as fast. Gas is cheap now. It won't be forever. Avoid V Drives, and gas engines. Also, avoid buying a boat that needs to be re powered unless it's a dream boat that you will keep forever and is dirt cheap. Or, if you are independently wealthy, then buy whatever you want and deal with what the consequences are. But even then, don't buy a V Drive.
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