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Old 03-18-2019, 08:29 AM   #1
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Cat 3116 turbo engine life

Gary here from Ohio,
Last week I posted about wanting to do an engine swap on a Mainship 35/39
to a lower horsepower, with all sorts of responses. Mostly pointing to suck it up and pay for the fuel. Thanks to all for those responses.

Let me explain myself here...When I get this boat I plan on living on and using it so it is going to get some hours. Hours means fuel so I want to get that down as low as possible...Duh!
Our last 2 diesel cars...A "Scandal" VW jetta sportwagon and now an Italian diesel chevy cruze, with fuel computers get in the mid 40's mpg BUT that is only when the motor is cranking about 19-2000 rpms. Any lower and it drops to as low as 16mpg any higher and it is off the charts.

After I placed the comment about maybe wanting to swap motors for a smaller horsepower I came up with a whole new can of worms!

Engine life of a turbo charged caterpillar 3116?

AN online crash course seems to point to the fact that pumping a lot of horsepower into a basic cat, or any motor can seriously lessen the life of that motor in a boat. Two or 3 guys seem to think that 1,000 hours is a lot on one of these turbo motors?
I keep going back to two different mainship ads ...one cat has 4,400 hours and the other 2,700 both turbocharged and I have no way of knowing the extent or accuracy of any maintenance done other than to note the holds seem spotless.
In browsing through well over 100 ads for trawlers from 34 to 40 feet there are a lot of 3-6000 hour Lehmans and Perkins' and in trying to study, these seem to putt along for well into 6-8,000 hours before a major overhaul is needed. One guy claimed 14,000 on a 4 popper perkins.

I guess my question is twofold:

1) What kind of life can one expect out of a cat or yanmar or any other turbocharged 270-350 hp diesel?

2)Since I am going to be constantly putting around at low rpms what all is involved in changing a turbocharged diesel engine back to a naturally aspirated one?
If you can do it then what kind of money, expertise would be involved in doing so??
Again I am a hands on mechanical guy with just enough knowledge to be not so dangerous!
Thanks in Advance, Gary
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Old 03-18-2019, 08:49 AM   #2
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there's way to many variables to give a accurate expected engine life on pleasure craft engines. i would more worried about how it was maintained and operated than going by the hr meter.
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Old 03-18-2019, 09:06 AM   #3
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As you experienced with your car fuel use is determined by engine load, not available HP.
A turbo does not shorten the life of an engine or increase fuel used; The operator does that by using the extra HP the turbo provides.
The only risk involved with a used turbo engine as opposed to a non turbo engine is much more work, (HP ) did the owner use.
With proper care engine life is determined by work done not how much work it could do.

Many makers offer 200 HP to 500 HP engines based on the same block. The life of the higher hP version will only be shortened if that extra power is used.

And no you don't have to just suck it up. Slow down and fuel use will reduce. Boats that can go fast use about the same fuel at slow speeds as those that cant go fast. Only when they go fast do they use the more fuel.
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Old 03-18-2019, 09:39 AM   #4
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I think you might have missed the point

Quote:
Originally Posted by gfr51 View Post
Gary here from Ohio,
Last week I posted about wanting to do an engine swap on a Mainship 35/39
to a lower horsepower, with all sorts of responses. Mostly pointing to suck it up and pay for the fuel. Thanks to all for those responses.

Let me explain myself here...When I get this boat I plan on living on and using it so it is going to get some hours. Hours means fuel so I want to get that down as low as possible...Duh!
Our last 2 diesel cars...A "Scandal" VW jetta sportwagon and now an Italian diesel chevy cruze, with fuel computers get in the mid 40's mpg BUT that is only when the motor is cranking about 19-2000 rpms. Any lower and it drops to as low as 16mpg any higher and it is off the charts.

After I placed the comment about maybe wanting to swap motors for a smaller horsepower I came up with a whole new can of worms!

Engine life of a turbo charged caterpillar 3116?

AN online crash course seems to point to the fact that pumping a lot of horsepower into a basic cat, or any motor can seriously lessen the life of that motor in a boat. Two or 3 guys seem to think that 1,000 hours is a lot on one of these turbo motors?
I keep going back to two different mainship ads ...one cat has 4,400 hours and the other 2,700 both turbocharged and I have no way of knowing the extent or accuracy of any maintenance done other than to note the holds seem spotless.
In browsing through well over 100 ads for trawlers from 34 to 40 feet there are a lot of 3-6000 hour Lehmans and Perkins' and in trying to study, these seem to putt along for well into 6-8,000 hours before a major overhaul is needed. One guy claimed 14,000 on a 4 popper perkins.

I guess my question is twofold:

1) What kind of life can one expect out of a cat or yanmar or any other turbocharged 270-350 hp diesel?

2)Since I am going to be constantly putting around at low rpms what all is involved in changing a turbocharged diesel engine back to a naturally aspirated one?
If you can do it then what kind of money, expertise would be involved in doing so??
Again I am a hands on mechanical guy with just enough knowledge to be not so dangerous!
Thanks in Advance, Gary
You donít have to duck up anything. If you go at Hull speed or slower a turbo driven large engine will give you the same mileage as a smaller engine. Regardless of engine size it takes x horsepower to move the boat y knots through the water. This is physics and there is no way around it. I can already hear some folks saying that even at idle the larger engine whom burn more than the smaller one. This is true. But over the lifetime of ownership this amount will be almost immeasurable.

Turbos in fact increase efficiency. This is why you will not find normally aspirated 18 wheelers on the road. Some large trucks even have double turbos.

Turbo driven engines require more work because you will generally have an aftercooler that will need bi-annual maintenance.

Engine life is determined, as some have said, by how the engines are run. My two Cummins 330 hp engines will drive my 50,000 pound boat to 15 hp, but I usually run her at 8 - 8.5 knots. Some folks have reduced this equation to: engine life is determined by the amount of fuel burned. At trawler speeds, my boat burns 5 gallons an hour. I would expect the engines to last 20,000 hour or more at that consumption rate. If I ran the boat at 11 to 12 knots and burned four times the fuel, I would expect the engines to die considerably faster.

You will appreciate having the option to go faster if you need to make a bridge opening or wait an hour for the next one.

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Old 03-18-2019, 09:39 AM   #5
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Gary
Suggest you go to boatdiesel.com and read up on the engines you are considering. It will cost you $25 to access the files you want to pull up. Also, insure you have the specific engine data in hand.

And re-read Big Cat's advice.
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Old 03-19-2019, 06:51 AM   #6
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"Many makers offer 200 HP to 500 HP engines based on the same block. The life of the higher hP version will only be shortened if that extra power is used"

Instead of engine hours as a measure , fuel consumed is a better metric.

As you will be at the low end of fuel use your engine life in hours should be grand.

The hassle is going "too slow" the turbo may not see enough exhaust to produce any boost , and just be an obstruction .

Some engines can remove the turbo , as the stock compression ratio (CR) was kept with the turbo added.
Some lowered the CR , these need! the turbo to operate acceptably.

If you can remove the turbo easily , you should contemplate a prop change , to produce more thrust at the low RPM.

This would increase efficiency at low speed, although dropping from say 2GPH to 1.5 might take a lot of run time to pay for the new prop.

As the old higher load / higher speed prop could be reinstalled , resale value would be maintained.
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Old 03-19-2019, 09:46 AM   #7
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It will probably be much easier to sell the boat later if you keep the motor stock. Run it how you like, and maintain it like it costs a lot of money to replace. Keep your documentation and spend $25 on oil analysis at each oil change.

When it is time to sell, your past analysis and documentation will facilitate a quick sale.
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Old 03-19-2019, 04:17 PM   #8
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The engine has a continuous and heavy duty rating, both at 205 hp and 2400 rpm. So if you keep the rpms down you can expect long service with proper maintenance. And the engine was designed to make rebuilding easy. An engine kit (sleeves, pistons, rings and gaskets) runs $1500 to $2000 depending on the piston type if you buy from an ag dealer. Not including a mechanic if you can't do it. Head, injectors, turbo and maybe injector pump are usually rebuilt at the same time.
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Old 03-19-2019, 09:32 PM   #9
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gfr -

Caterpillar’s 3116 never found the praise that it’s predecessor the 3208 did. However, it’s a good reliable engine at lower horsepower (<300hp) demand applications, and I have read reports of 10,000 hrs without major overhaul. I own one and have found it very fuel efficient and clean burning. Parts are reasonably priced, maintenance is easy DIY or easy to find service, except for the rare fuel rack adjustment/injector synchronization which is a job for a Cat tech. As mentioned above, join Boatdiesel to read up on the 3116 and form your own opinion.
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Old 03-20-2019, 08:59 AM   #10
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Originally Posted by Archhibb View Post
gfr -

Caterpillarís 3116 never found the praise that itís predecessor the 3208 did. However, itís a good reliable engine at lower horsepower (<300hp) demand applications, and I have read reports of 10,000 hrs without major overhaul. I own one and have found it very fuel efficient and clean burning. Parts are reasonably priced, maintenance is easy DIY or easy to find service, except for the rare fuel rack adjustment/injector synchronization which is a job for a Cat tech. As mentioned above, join Boatdiesel to read up on the 3116 and form your own opinion.
Hello, Thanks for your response.
Since you own a cat can I trouble you for the motor's sweet spot?

On the last 2 of our diesel cars it was /is right around 1,950 to 2,200 Much above that and goes went way downhill.
BUT
more importantly for me is when you putt around at 12 to 1500 economy is way back down there again...
Do you have a fuel computer and can throw out some figures?

Having NO experience with then it Seems like on a trawler a two speed gearbox might be a neat thing.
I read where some cat 3116's are coupled with a variable trans.

Oh since I see Marblehead on your logo do you have any experience with the Ditch heading south, or north? Insight on that if you please.

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Old 03-20-2019, 09:37 AM   #11
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I have twin 3116 turbos 350 hp. They have run flawlessly and now have 4,900 hours. Routine oil changes with CAT SAEO oil is the key to long life. (SAEO= Special Application Engine Oil) and is designed specifically for the CAT 3116 and 3126 marine engines. I run at 1,950 rpm most of the time although slower if I'm in the mood.
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Old 03-21-2019, 07:10 AM   #12
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Gary -

I haven’t heard of a variable speed trans with 3116’s, but suppose anything is possible.

I don’t have floscans or other fuel metering, but my estimated fuel economy is similar to Cat’s posted GPH specs below: (E Rating prop demand)
1800 - 4.2
2000 - 5.7
2200 - 7.5
2400 - 9.7
2600 - 12.2
2800 - 15.8

In my semi-displacement 35ft. downeast, there is no sweet spot for the engine; just even power delivery across the tach. I read somewhere that the 3116 burns 2.3 gph at 1400 rpms.

No experience with the Ditch, sorry.
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Old 03-21-2019, 11:56 AM   #13
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Look at the engine charts and find the torque peak, that is the "sweet spot." Honestly, in the list of costs of running a boat, fuel is almost immaterial. Depreciation, moorage, insurance and haulouts are going to hurt more than fuel. Engine maintenance, pump repairs and replacements, batteries etc, all expensive; don't obsess over the fuel burn, pick a speed you like for comfort, ride and quiet and just buy the fuel.

Don't over-pay, there will be things wrong with it and don't change much until you've operated it for a while. Like I said, don't fuss over fuel. I didn't buy any fuel for 2 years (big tanks) then I paid about $3000 last summer, moorage was $6000, haul out $3500, insurance $1900 annually, get the picture?
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Old 03-21-2019, 03:04 PM   #14
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What Xsbank said. Fuel is the cheapest part of boating with a single screw boat.
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