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Old 16-10-2020, 17:41   #16
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Common Rail Experience?

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Originally Posted by Jim Cate View Post
Is this supposed to reflect good fuel efficiency? Our bog standard old Kubota based Nanni 43 pushes our ~25000 lb boat at similar speeds using only ~2.5 liters/hr.



Something fishy here...



Jim


Iíve read that CR diesels arenít more efficient- possibly same as newer mechanical diesels- because they ďspendĒ more fuel with preignition pulses in the injectors that reduce clatter and noise and make it smooth.
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Old 16-10-2020, 17:56   #17
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Re: Common Rail Experience?

Does this translate to longer life for internal parts?
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Old 16-10-2020, 20:01   #18
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Re: Common Rail Experience?

The new electronic controlled diesels are amazing. At least 20% more efficient than the old natural aspirated counterparts such as my Perkins 4.236.

However, the tradeoff is they are more finicky and are more difficult for a shade tree mechanic to get going. It's more than just an ECU. An older style diesel needs compression and clean fuel. That's it. Newer CR have a much more narrow deadband of acceptable operating conditions in order to achieve that efficiency and the emissions standards.

Its a tradeoff. I thought about repowering as 20% efficiency improvement means I need less fuel. But in the end, I felt I had a better chance of completing a trip with an old school diesel. So I rebuilt my old Perkins. Decision was based on repairabilitly, not cost

Peter
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Old 17-10-2020, 05:02   #19
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Re: Common Rail Experience?

Where do you get the 20% number? Maybe thatís compared to really old mechanical diesels? but my beta 50 fuel curve is nearly identical to similar Yanmar common rail fuel curves
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Old 17-10-2020, 06:03   #20
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Re: Common Rail Experience?

The efficiency gains from common rail vs fairly modern mechanical injection are mostly at lighter loads, such as you'd see running slowly in a planing hull powerboat. They tend to tolerate sustained light load operation better as well. And the more precise control also allows some design improvements in turbo engines that tend to give them a bit flatter power curve than older turbo diesel designs.
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Old 17-10-2020, 07:14   #21
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Re: Common Rail Experience?

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Where do you get the 20% number? Maybe thatís compared to really old mechanical diesels? but my beta 50 fuel curve is nearly identical to similar Yanmar common rail fuel curves
If you think that even a modern mechanical diesel such as a Beta is as efficient as well groomed diesel, well, you're wrong. If they were, there would have never been EPA Tier emission standards for Diesels.

I can tell you that I've run essentially the same boat ( a Willard 40 Trawler) over approx 1000 nms of roughly the same waters along the pacific coast. One had a Tier 2 Deere 4045TA and the other had a Perkins 6.354N, roughly the same horsepower. The JD burned about 1-1/3 gph, the Perkins burned 1-3/4 gph. No idea what the fuel burn curves say, but I know for certain what they burned on each delivery. A Tier 3 CR would be even more efficient.

That said, having run a couple newer boats with modern Cat and Cummins CR engines, when they go tits-up, I'm flummoxed and dead in the water. Technicians come with their computer and start swapping parts until something finally works. Or not. Last dead CR was due to a tiny push together plug with some sort of control wires. The terminals had become corroded. Owner had been talked into about $5k in engine parts before a rock solid electrician found the terminal issue in about 20 mins.

I'll note that farmers are complaining about inability to self-repair newer equipment. Lost time and of course expense. It's a big issue in the small farmer community.

Really depends on your cruising grounds and your level of comfort with mechanicals. Modern diesels are incredibly clean and efficient. I plan on more remote destinations and while I'm a pretty fair mechanic, I'd starve if I had to make a living turning a wrench. My choice is a classic piece of iron similar to your Beta (Perkins 4.236). But make no mistake, in my opinion and experience, it does not compare well in efficiency. There is a tradeoff

Peter
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Old 17-10-2020, 08:27   #22
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Re: Common Rail Experience?

Dock
what you really need to find out is how is the manufacturer handling the ECU and systems diagnosis?
Some like I believe Cat and maybe Volvo are acting like Apple, that is no third part diagnostic equipment is allowed as they keep their code proprietary, and unless I’m mistaken you can’t even carry a spare ECU as it MUST be programmed by the factory proprietary diagnostic tool before it can be used, and they will NOT program one except to put it on an engine, so no spares.

Contrast that to the GM / Isuzu Duramax engine that software and cod was released almost immediately which allowed all kind of programming and monitoring allowed, and I mean you could monitor everything fuel pressures, temps, air density, temps you name it, way more than a dozen parameters. This was gold when you were troubleshooting as you knew a sensor was bad if it said the air temp was 300F or -50F etc.

So find out if the engine your looking at if the manufacturer controls the code and diagnostic equipment or are you allowed to monitor it through third party software.

The only real advantage of common rail is two fold, first the NVH or noise vibration and harshness can be as smooth and quiet as a luxury cars gas motor, and second is pollution control, a common rail can be a clean burning Diesel.
But unfortunately there is no big advantage in fuel burn.

Go listen to a modern Diesel engine pickup truck now, they are exceptionally quiet, and that’s because of common rail.

on edit, not necessarily relative to a sail boat motor, but Common Rail can make huge amounts of power, it’s made Diesels into hot rods, and without Common Rail, Diesels would essentially dead as your not passing road emissions without it.
https://youtu.be/dKc7d73yOSs

on this video, pay attention to the exhaust, notice how clean it is. that’s Common rail and I’m sure Nitrous, but even nitrous won’t clean up smoke without advanced programming.
They are both the GM / Isuzu pickup truck motor, the Duramax
https://youtu.be/6UZpKI27KXA
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Old 17-10-2020, 10:17   #23
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Re: Common Rail Experience?

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If you think that even a modern mechanical diesel such as a Beta is as efficient as well groomed diesel, well, you're wrong. If they were, there would have never been EPA Tier emission standards for Diesels.


Well the Beta is tier 3 and the fuel burn curves are very similar to CR Yanmars so YMMV I guess. I think an old Perkins is a very different engine. And see prior post from A64. Iíll dig out an article somewhere which shows that thereís pretty similar burn with new efficient mechanical diesels and CR- I think the NVH reduction costs a little extra fuel for CR
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Old 17-10-2020, 10:50   #24
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Re: Common Rail Experience?

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...

on this video, pay attention to the exhaust, notice how clean it is. thatís Common rail and Iím sure Nitrous, but even nitrous wonít clean up smoke without advanced programming.
They are both the GM / Isuzu pickup truck motor, the Duramax
https://youtu.be/6UZpKI27KXA
Moving from Low Sulfur Diesel(LSD) to Ultra Low Sulfur Diesel(ULSD) reduced the amount of sulfur in diesel by about 97%. My 7.3L diesel would smoke pretty good if I sorta put my foot into the go pedal with LSD. Now, with ULSD, I really have to push on the go pedal to get any smoke at all. I don't do that very often but the difference in black smoke is huge just from there being less sulfur in the fuel.

Years ago we were at a boat show and talked with the JD representatives about the common rail(CR) engines. Non CR diesels only needed fuel and air to work. CR diesels need fuel, air and electrical power to run. No power and the diesel is not gonna work. Not a good vulnerability for a engine on a boat in far away places.

What I have read is that JD will not provide a programmed ECM as a backup for your engine. This is just no acceptable for a boat that is traveling the world.

Lightning is a big concern of ours since a modern engine is completely dependent on electronics.

I have compared engine HP and fuel burn on a bunch of JD engines. Comparing engines with the same engine model, with similar maximum HP, the same rating, but with different levels of emissions standards shows that difference in fuel burn at a reasonable/normal operating RPM is minimal However, at max RPM, the older engines have better fuel burn. Course it is often not an exact comparison, since at max RPM, the engine generate slightly different HP. JD makes it harder to compare different RPM/HP fuel burns because they sometimes round up/down the fuel usage.

A JD 4045TFM75 and 4045TFJ85 engine with a M2 rating both have a max RPM of 2400. The M75 engine, earlier emissions regulations, has a maximum of 121 HP and the M85 engine has a maximum HP at 125. The M75 engine burns 6.7 GPM vs the M85 at 7.7. A lovely old Gardner 6XLB with 127 HP burns 6.3 GPM. But who runs max RPM for long periods?

Later,
Dan
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Old 17-10-2020, 11:23   #25
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Re: Common Rail Experience?

Better get used to the idea of common rail, because that’s all there will be available soon.
It’s like overhead valves, I’m sure some complained about those too, but try to find a new flat head motor.
Hemp rope, canvas sails, and mechanical injected Diesels will soon be all grouped together.
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Old 17-10-2020, 15:34   #26
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Re: Common Rail Experience?

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Well the Beta is tier 3 and the fuel burn curves are very similar to CR Yanmars so YMMV I guess. I think an old Perkins is a very different engine. And see prior post from A64. Iíll dig out an article somewhere which shows that thereís pretty similar burn with new efficient mechanical diesels and CR- I think the NVH reduction costs a little extra fuel for CR
This is misleading. Beta complies with category 1 tier 3 standards which was a voluntary standard in the late 90s. The testing regime for category 3 tier 3 compliance is difficult and expensive. Beta gets by because their largest engine is under 100hp.

Its a good engine. Would be my choice I'm current offerings. But it's not the same tier 3 engine as the big boys adhere to.

Peter
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Old 17-10-2020, 16:05   #27
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Re: Common Rail Experience?

Do you guys all drive all cars with carburetors so you donít have to trust EFI? Do you not drive your own car on a road trip because you donít trust the ECU?

Come on. Common rail electronic diesels have been in use around the world for years in the most demanding commercial and industrial uses and are better in every way.
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Old 17-10-2020, 16:15   #28
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Re: Common Rail Experience?

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Do you guys all drive all cars with carburetors so you donít have to trust EFI? Do you not drive your own car on a road trip because you donít trust the ECU?

Come on. Common rail electronic diesels have been in use around the world for years in the most demanding commercial and industrial uses and are better in every way.
Question isn't whether it's reliable - it is. Question is whether it can be repaired if a failure does occur. It often cannot with a technician with diagnostics. If your cruising grounds are within the gravitational pull of a technician, you're golden.

Interesting article about John Deere preventing farmers from repairing their own equipment. Farmers lost this battle.

https://www.bloomberg.com/news/featu...00-000-tractor
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Old 17-10-2020, 16:18   #29
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Re: Common Rail Experience?

You won't care what the mileage is if your single engine doesn't run when you need it.

My diesel PU got towed 3 times last year. Each time electronics you need software and a computer to diagnose.
I won't have a engine on the ocean that needs electricity to run.
Everything done to diesels and fuel in the last 20 years has made them less reliable.
Some engine makers own the rights to the diagnostic equipment and will only sell it to dealers. There's a Right-to-Repair effort going thru farm country because farmers can't repair their own electronic tractors and other equipment.
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Old 17-10-2020, 16:34   #30
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Re: Common Rail Experience?

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You won't care what the mileage is if your single engine doesn't run when you need it.

My diesel PU got towed 3 times last year. Each time electronics you need software and a computer to diagnose.
I won't have a engine on the ocean that needs electricity to run.
Everything done to diesels and fuel in the last 20 years has made them less reliable.
Some engine makers own the rights to the diagnostic equipment and will only sell it to dealers. There's a Right-to-Repair effort going thru farm country because farmers can't repair their own electronic tractors and other equipment.
Agree. Electronics and software make these engines very efficient. Unfortunately, these are relatively fragile systems compared to traditional diesel engines. Add in salt water environment and you are asking for trouble if you're cruising remote locations.

Personal decision. Depends on what risk is most comfortable for you. I like my chances better with an old-school diesel. But that is not a recommendation, just what works for me.

Peter
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