Replacement diesel?

[Boat]

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/

 

[Pete Meisinger]

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.

pete

 

[FF]

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 .

 

[Rufus]

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.

 

[FF]

"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.

 

[rslifkin]

"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.

 

[bluebyu]

Nice looking cruiser:
https://www.dimillosyachtsales.com/boat/1984/midnight-lace/rumrunner-express/2848/

 

[Ruffryder]

Hyundai Seasall 270S

http://www.trucktrend.com/features/1801-hyundai-seasall-s270-advanced-ultralight-marine-v-6

 

[Bryant]

Replacement diesel

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".

 

[Bryant]

Replacement diesel

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.

 

[Bryant]

Diesel repowering.

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

What ^ he said. And you would still have V Drives. Find another boat.

 

[Transaxial]

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.

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.

Don't all of us with old boats do a little dreaming and planning for "what if" scenarios, specially with engines that are possibly past their best. I just happen to have some measurements handy for a Cummins 6BT 5.9 that would fit in my boat As rslifkin says the QSB is 33.8" high. Some other 6BT engines are slightly less than that but they show a turbo sticking up above the valve covers 3-4". If you used a water cooled marine exhaust manifold and turbo, the turbo seems to be at or below the top of the valve covers. In my boat that would make the difference to fitting in the space. Another important measurement is height above crank center line, which is about 21-22" on the 33-34" tall engine. That leaves about 12" below CL.

The 8.2s did run faster than a lot of diesels but they are running the Dodge truck engines over 3,000 rpm now, although I don't like to. So a 6BT could be run with the same ratio and props as you have said you want to.
27kts-2800 rpm, 20kts-2100, 12 kts-1250. All good engine rpm range for what you want to do with the boat.

As far as V drive transmissions, there is a variety of Twin Disc 506 gears in different configurations of V drive, rear drive with 5 1/2" down offset, and 8-10 degree down angle output shafts.

It would be a big job to repower, coming from one who has done a few. If your 8.2s are running good for your low cruise speed requirement, I might just enjoy it the way it is. Go through everything and do some good preventative maintenance. I think my GM 6.5 turbo in a 1993 2500 truck is in the same engine family. I know of lots of them that melted down in the area of the back two cylinders on the right side where the crossover pipe and turbo meet because of a lack of cooling capacity. There were aftermarket kits that had high volume water pumps (83 gpm to 130ish gpm), high volume thermostats, Duramax 9 blade fan and viscous drive that engages at a much lower temperature than the stock hub, and on the pickup we put in a thicker rad core. At the same time we added a 4" exhaust system and you would think it must be a totally bigger engine with heating only when pulling on the hottest days now. 250 k miles and still running strong! Gets great mileage. It was mentioned to add a vent line in the cooling system so thought cooling might be concern on these engines too.

Good luck and keep us in the loop!