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Old 01-10-2013, 01:59 PM   #41
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Greetings,
Hall of Farmer? You KNOW farmers that look like that?
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Old 01-10-2013, 02:06 PM   #42
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While the engine is a large item in a trawler , most folks will not purchase a boat based on the engine.

Some will avoid a specific brand (like Volvo) but few will base the selection on what is installed.

In most slow cruisers the ability to operate at a small percentage of the rated power is a plus.

And active ongoing support from the engines marinizer is a big plus.
nice to have reserve power but i believe engines are designed to be most efficient at rated hp and load. When operated way way below the design rpm there is a loss in efficiency and more combustion byproducts form to dirty the oil, engine, and air. So i guess its kinda a trade off. Maybe not because modern computer controlled engine systems can tweak the air fuel ratio to maximize efficiency.
So should we all go out and re power with new computerized efficient engines?.....

anyone know the answer?
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Old 01-10-2013, 03:08 PM   #43
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If you are looking at previously owned boats, the brand name of the engine will often be less important than how well it has been maintained. On a much older boat, do ask around about parts availability. Some engines that were in common use a while back, (the Cummins "triple nickel" comes to mind as an example) might have been fabulous engines in their day, and maybe still are if well maintained, but eventually something will break and parts availability can be an issue.

I'm a huge fan of Perkins. Just personal preference and experience. There are many other good choices as well.

If hoping for a long lifespan from your engine(s), one of the old "isms" that seems to be consistently valid is the 2:1 ratio. See if you can find an engine that displaces two or more cubic inches for each HP developed. (Example would be a 354 cu in inline six producing 165 HP). Especially some of the newer engines rely on running much higher RPM to achieve rated HP. Most of those legendary 15, 20, 25,000 engines are slower turning.
Not sure the 2:1 thing is valid with todays modern engines based upon what i see in the auto industry in which its closer to 1:1 and they seem to live long trouble free lives. All turbo's and last hundreds of thousands of miles. Of course we wont know for years if this will hold true for the marine versions
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Old 01-10-2013, 03:16 PM   #44
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Auto engines only WORK about 20% of the time. They're coasting or idling the rest. Marine engines are closer to 80%-90%. No coasting. I knew a fellow with two 6-71 TT's in a sport fish. Expected time before a re-build was about 5000 hrs. NA DD's last substantially longer than that. Anecdotal yes, but just sayin'
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Old 01-10-2013, 03:30 PM   #45
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Good engine / Bad engine .

Well after thousands of hours using engines.

There are days that end with GOOD ENGINE , GOOD ENGINE!

Then there are days that just never seem to end BAD ENGINE BAD !

Most engines seem to need a thump from a very big hammer at some point in there life.

Some folk carry a big stick around. Yet for me that "pollish socket set" a very big hammer and some epoxy along with some life saving beer seems to get me home most of the time.

YMMV.
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Old 01-10-2013, 06:09 PM   #46
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Not sure the 2:1 thing is valid with todays modern engines based upon what i see in the auto industry in which its closer to 1:1 and they seem to live long trouble free lives. All turbo's and last hundreds of thousands of miles. Of course we wont know for years if this will hold true for the marine versions
Can you think of any disadvantage in choosing a higher displacement to HP ratio, when available?
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Old 01-10-2013, 06:38 PM   #47
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My advice is to check for parts availibilty for any engine you are looking at. Some manufacturers do not support their older products, Volvo in particular.
Are you willing to bash Chevrolet for no longer supporting the Corvair?
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Old 01-10-2013, 07:00 PM   #48
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Can you think of any disadvantage in choosing a higher displacement to HP ratio, when available?
Sure...lighter, smaller, more efficient...need I go on????
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Old 01-10-2013, 07:03 PM   #49
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Are you willing to bash Chevrolet for no longer supporting the Corvair?
Sure....if there were as many Corvairs on the road as there are older Volvo's marine diesels still in use percentage wise....

That's why Furuno gets such high marks for supporting their marine electrionics for so long..usually WAY past the competition. And that's why the smaller vessel (read less big bucks) commercial crowd speaks so highly of them.
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Old 01-10-2013, 08:21 PM   #50
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Sure...lighter, smaller, more efficient...need I go on????
I was referring to engine longevity, the advantage originally claimed for the old 2:1 standard. Even *if* some smoking hot little diesel revved up to 3500 or more is "lighter, smaller, more efficient"- is it likely to outlast, or last as long, as a larger heat sink running at 1800 to 2000?

From the longevity aspect, I fail to see any advantage to a high revving small engine over a slower revving larger engine rated at the same HP, and I see no disadvantage in choosing the larger engine.

It would be my opinion that engine weight in a true trawler application, running near hull speed, isn't as crucial as with a ski boat or a day cruiser.
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Old 01-10-2013, 08:40 PM   #51
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For the OP---- One more thing to know about the Ford Lehman 120. Their raw water setup is part of the Lehman marinization package. It includes a Lehman-designed pump drive aka drive coupler that gets its power from the accessory case on the front of the engine. The drive powers an off-the-shelf Jabsco flexible impeller pump.

The Lehman drive coupler was designed by Bob Smith and he's the one who told me what I'm about to tell you (which was also seconded by our diesel shop).

The drive coupler is not a good design. It seemed to be a good design at the time but it proved to be very difficult to manufacture and is the only Lehman component to have ever had a factory recall (according to Bob).

But over time the drive proved to have a fatal flaw (which was not the cause of the recall) which is the drive tang on the pump end of the driveshaft. The fatal flaw is that eventually the tang, which is like a real fat screwdriver blade, fatigues, cracks, and breaks.

When it breaks--- and according to Bob all of them eventually will--- the raw water pump immediately stops and the flow of raw cooling water immediately ceases. At cruise power it takes only moments for the engine to overheat, and the number one killer of the FL120 is overheating (for several reasons).

The problem is that the Lehman drive coupler is no longer available new and hasn't been for a long, long time. While the tang can be repaired by welding, Bob told me that these repairs are very short-lived.

So there are only two solutions. One is get another drive coupler off an FL120 that is being parted out. Problem here, of course, is that the tang on the parted-out coupler may itself be close to failing.

So the real solution is to toss the whole thing, Lehman drive coupler and the Jabsco water pump, and replace them both with a brand new, one-piece Johnson pump that is a bolt-on replacement.

This is what we did on both our FL120s when the removal of one of the Jabsco pumps for overhaul revealed a failing tang on the drive coupler. So we had the couplers and pumps on both engine replaced with 1" Johnsons. The coupler on the other engine proved to be okay so we have kept it and the Jabsco attached to it as an emergency back up raw water pump system should we ever need it (not likely).

This is a very specific detail, I know, but should you end up looking at a boat with one or two FL120s, keep in mind this potential problem, which becomes more likely the more hours there are on the engine(s). If the engine(s) in a boat you're looking at has/have the Johnson conversion, that is a Wonderful Thing.
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Old 01-10-2013, 08:52 PM   #52
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Chuck,
Nobody should care about how long an engine lasts or what rpm it is intended to run at. At least 99% of us will never wear out the engine w the shortest engine life expectancy. Lots of engines get killed but not worn out. So what does it matter how long some guru says it's supposed to last or what rpm it's run at. Makes no never mind.
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Old 01-10-2013, 08:55 PM   #53
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We're looking at slow trawlers in the 35 to 45 ft range so I guess i'm looking for opinions on engines that would be appropriate for a boat of that size.
I have a 1991 Perkins TW6.354.4 it has 115bhp at 1500 rpm with max revs at 2850rpm.

Perkins 6.354 have been widely used in the marine and agriculture industries. They have turbo versions T6.354 and all sorts. Google and you'll get the info you require.

Cheers
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Old 01-10-2013, 08:59 PM   #54
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Good engine / Bad engine .

Well after thousands of hours using engines.

There are days that end with GOOD ENGINE , GOOD ENGINE!

Then there are days that just never seem to end BAD ENGINE BAD !

Most engines seem to need a thump from a very big hammer at some point in there life.

Some folk carry a big stick around. Yet for me that "pollish socket set" a very big hammer and some epoxy along with some life saving beer seems to get me home most of the time.

YMMV.
thats funny but true. reminded me of one time i paid a guy almost $1000 to fix an engine and it still was the same as when he started. He said another $500 would fix it. I didnt have $500 but i had a six pack and bought a book, some wrenches were applied and with the help of the cardboard six pack which i used to make a gasket the engine was fixed and ran for years like that trouble free. Cost for the repair, one six pack and elbow grease. I wuz 21 at the time. Beer can be a live saver
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Old 01-10-2013, 09:13 PM   #55
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I was referring to engine longevity, the advantage originally claimed for the old 2:1 standard. Even *if* some smoking hot little diesel revved up to 3500 or more is "lighter, smaller, more efficient"- is it likely to outlast, or last as long, as a larger heat sink running at 1800 to 2000? Yanmars have proven higher speed doesn't necessarily mean higher maintenance or shorter life...

From the longevity aspect, I fail to see any advantage to a high revving small engine over a slower revving larger engine rated at the same HP, and I see no disadvantage in choosing the larger engine. Unless you don't have or want more room.

It would be my opinion that engine weight in a true trawler application, running near hull speed, isn't as crucial as with a ski boat or a day cruiser. True unless you have a pocket cruiser or engine configuration where weight distribution could be enhanced by a smaller engine...as in cockpit mounted to v-drives...etc..etc...

Heavy metal is a wonderful thing...but times are a'changing....
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Old 01-10-2013, 09:20 PM   #56
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Chuck,
Nobody should care about how long an engine lasts or what rpm it is intended to run at. At least 99% of us will never wear out the engine w the shortest engine life expectancy. Lots of engines get killed but not worn out. So what does it matter how long some guru says it's supposed to last or what rpm it's run at. Makes no never mind.
Certainly nobody is required to care. If the smaller high-rev diesels eventually develop a reputation as "2000 hour engines" or "2500 hour engines", and you put 150-200 hours per year on your engine for a decade before selling it it might have an impact on your resale value. Once again *if* the smaller high-rev diesels eventually develop a reputation....

We know what reputation the traditional, slower turning engines have developed and a 2000 hour diesel engine is no big deal, (pending oil analysis, etc). But try to sell a gas boat with 2,000 engine hours. A gas engine is going to be considered worn out at 2,000 hours by a lot more people than currently considering a diesel worn out with the same usage.

Until there is a widespread consensus about durability of the smaller engines, resale is a possible (not saying certain) concern.

Somewhere there are some pretty solid numbers about the relationship between the amount of fuel that has been pumped through a cylinder and its life expectancy without a rebuild. I'll try to find that. It's supposedly even more accurate that engine hours alone.
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Old 01-10-2013, 09:33 PM   #57
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Certainly nobody is required to care. If the smaller high-rev diesels eventually develop a reputation as "2000 hour engines" or "2500 hour engines", and you put 150-200 hours per year on your engine for a decade before selling it it might have an impact on your resale value. Once again *if* the smaller high-rev diesels eventually develop a reputation....

We know what reputation the traditional, slower turning engines have developed and a 2000 hour diesel engine is no big deal, (pending oil analysis, etc). But try to sell a gas boat with 2,000 engine hours. A gas engine is going to be considered worn out at 2,000 hours by a lot more people than currently considering a diesel worn out with the same usage.

Until there is a widespread consensus about durability of the smaller engines, resale is a possible (not saying certain) concern.

Somewhere there are some pretty solid numbers about the relationship between the amount of fuel that has been pumped through a cylinder and its life expectancy without a rebuild. I'll try to find that. It's supposedly even more accurate that engine hours alone.
Not sure where that bad info came from or how old it is....most modern marine engines nowadays are going much longer....inboard, outboard, gasd, diesel...etc...etc...

We routinely put over 5000 hours on gas inboards in the assistance towing fleet and beat the livin' crap out of them compared to rec boaters.

The trouble with just using hours is that itn is of little relavenvce to how old all the expensive parts that are bolted on to it or how it's been used/abused.
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Old 01-10-2013, 09:35 PM   #58
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Certainly nobody is required to care. If the smaller high-rev diesels eventually develop a reputation as "2000 hour engines" or "2500 hour engines", and you put 150-200 hours per year on your engine for a decade before selling it it might have an impact on your resale value. Once again *if* the smaller high-rev diesels eventually develop a reputation....

We know what reputation the traditional, slower turning engines have developed and a 2000 hour diesel engine is no big deal, (pending oil analysis, etc). But try to sell a gas boat with 2,000 engine hours. A gas engine is going to be considered worn out at 2,000 hours by a lot more people than currently considering a diesel worn out with the same usage.

Until there is a widespread consensus about durability of the smaller engines, resale is a possible (not saying certain) concern.

Somewhere there are some pretty solid numbers about the relationship between the amount of fuel that has been pumped through a cylinder and its life expectancy without a rebuild. I'll try to find that. It's supposedly even more accurate that engine hours alone.
I know Cat engines started using gallons through as a benchmark at least 10 years ago for estimating rebuilds...never could find it again in their internet literature though. I got it straigh from them when i was emailing questions about my 3208s
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Old 01-10-2013, 09:38 PM   #59
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Not sure where that bad info came from or how old it is....most modern marine engines nowadays are going much longer....inboard, outboard, gasd, diesel...etc...etc...

We routinely put over 5000 hours on gas inboards in the assistance towing fleet and beat the livin' crap out of them compared to rec boaters.

The trouble with just using hours is that itn is of little relavenvce to how old all the expensive parts that are bolted on to it or how it's been used/abused.
glad you said that. I had remembered numbers on gas police boats with engine replacement from 15 years ago and they were seldom replaced before 5000 hours and they are beat to h.
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Old 01-10-2013, 09:58 PM   #60
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Chuck,
Nobody should care about how long an engine lasts or what rpm it is intended to run at. At least 99% of us will never wear out the engine w the shortest engine life expectancy. Lots of engines get killed but not worn out. So what does it matter how long some guru says it's supposed to last or what rpm it's run at. Makes no never mind.
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Originally Posted by psneeld View Post
Not sure where that bad info came from or how old it is....most modern marine engines nowadays are going much longer....inboard, outboard, gasd, diesel...etc...etc...

We routinely put over 5000 hours on gas inboards in the assistance towing fleet and beat the livin' crap out of them compared to rec boaters.

The trouble with just using hours is that itn is of little relavenvce to how old all the expensive parts that are bolted on to it or how it's been used/abused.
Well, you would be in a position to know, as you make your living towing in vessels with mechanical failures. I guess that the concept of gasoline inboards going 5000 hours, even when "beat to crap" is brand new to me. I wouldn't expect to be able to beat my diesel to crap and get that kind of service. That's a great thing to learn, so thanks.

Here's one possible source of the "bad information": From surveyor David Pascoe's web site:

"Performance Diesels Harken back to what I said about squeezing the maximum amount of power out of an engine block, along with what I said about cooling systems. I'm still stunned that I hear guys talking about diesel engines running 3, 4, even 6 thousand hours. I can count the number of engines I've seen with 3000 hours on them that have never been rebuilt on the fingers of one hand. And virtually every one of them were in slow speed, long range cruisers with superb maintenance. I raised a lot of flack from my previous article in which I stated that the AVERAGE diesel runs about 1000 -1100 hours before overhaul. I stick by that number, but you have to understand that the AVERAGE includes high performance diesels, as well as those folks who do not maintain their engines at all; the ones who run them until they stop.


High performance diesels cause a tremendous drop the average since the go fast diesels often go bang at 600 hours or less. If anyone would like to challenge that, take a tour of the Fort Lauderdale diesel shops and check out the hour meters on some of these boats. You'll find many of them are less than two years old.


Diesel engines are capable of having a long life when the power to displacement ratio is low. But when they start jacking up the power, beyond what the manufacturer originally intended, that benefit disappears. There is a very simple formula you can apply to estimate service life: simply multiply the cubic inch displacement of the engine times one. The result is the maximum amount of horse power you can have and still expect a reasonable service life. A 6V92 engine is 552 CID; at powers greater than 550, these engines don't last. At 450, they'll go 10 - 15 years easily.


We recently surveyed a yacht with a pair of 8V71N (naturally aspirated) Detroit Diesels rated at 325 hp that hadn't been overhauled since new 1981. Now, an 8V71 has a 568 cubic inch displacement; the fact that these engines have a 0.56:1 power/displacement ratio explains why they could run so long.


Conversely, divide the CID by the horse power, and the greater the result UNDER the factor of one (1), the longer engine life you can expect. If you have an engine with an 0.70 CID/HP ratio, then you can expect 3000 hours engine life. Otherwise, you are a victim of the myth."
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