Newer generation engines

keb · Jan 8, 2017

Hobomack said:
In our experience, reinforced by the advice of a major engine manufacturer, the current common-rail electronically-controlled engines in this size range are not prone to "carboning up" from uncombusted fuel because the fuel is metered so precisely to meet the power demand -- the concerns associated with operating a mechanically-controlled diesel at low demand are not applicable to the current generation.

Scott Helker
Helmsman Trawlers

I didn't want to hijack another thread regarding someones beautiful new boat delivery .... just a question. For those of us who are not diesel experts, when did the common rail electronically controlled engine become the standard for marine application? If one was looking in the used market, AND wanted to search only for boats that had this newer generation, what year would you start at? Or is there an easier way to identify these engines through model numbers commonly referenced on yachtworld?

eyschulman · Jan 8, 2017

I can not give you a year but most used boats are pre common rail. You would be looking most likely at a used boat five or less years old for engines with common rail. The technology is more pertinent to new builds and very recent boats. When I had my custom boat built in 2011 CR engines were readily available. Most of the boats on this site maybe( 95%+) do not relate to the common rail technology. If the boat has it and all the electronics are doing their job it makes a significant difference in how you can run your boat. You can even design a boat around the concept of multiple sweet spots of speed and my boat is exactly that. An old school diesel engine would not like that concept while a CR engine is right at home with different load demands.

drb1025 · Jan 8, 2017

My boat was built in 2010 and it does not have common rail engines.

Ski in NC · Jan 8, 2017

The Cummins QSB and QSC were hitting the market around 2005 (???). These are common rail. And they really do not seem to mind light load running. Super clean burning.

Volvo D4 and D6 have been out for several years, not sure when exactly. Also common rail.

Some smaller random offerings from Yanmar and Volvo, but I would avoid those.

I was initially spooked by computer engines, both common rail or other type electronic controlled injection. But they have proven quite reliable. Not so spooked any more.

tadhana · Jan 8, 2017

drb1025 said:
My boat was built in 2010 and it does not have common rail engines.

What engines do you have?

The common rail diesel fuel system was first developed in the 1990s as the engine manufacturers began to address the increasingly tight emission regulations here and in Europe. The emission regulations have been tightened over time and the engine manufacturers have met them with increasing sophistication in managing fuel, air and exhaust. Read computers all over the engine. In our 2009 Cummins QSB 5.9 there is a circuit board under the valve cover at each injector. Small diesel engines had been exempted but the lower limit has been slowly lowered and now many of the small sized marine diesels (100 hp) have to meet the emissions regulations. The latest marine engines must meet Tier 4 regulations.

drb1025 · Jan 8, 2017

Jd 4045

Ski in NC · Jan 8, 2017

Deere has some of their engines now with common rail, but not all of them.

BIG CAT · Jan 8, 2017

The use of common rail fuel systems varies from engine to engine and from one mfg to another. Cat only has 3 engines that use common rail fuel systems. Most all the others use cam shaft actuation with electronic control.

tadhana · Jan 8, 2017

This JD 4045 were probably previously under the displacement limit for the emissons regulations and the regulations did not aply to them. The lower displacement limit now covers most 4 cylinder engines.

Ski in NC · Jan 8, 2017

Cat has historically made their own fuel injection equipment while other mfr's buy theirs from Bosch, Denso, Stanadyne, etc.

When CR came to the market Cat may have gotten into a patent pickle. The probably could not make their own CR system without infringing. They certainly have been slow to adopt. I think the only smaller engines they offer with CR are built entirely by another company in the EU and painted yellow. I think some of their large engines are CR, but does not apply to this market.

drb1025 · Jan 8, 2017

tadhana said:
This JD 4045 were probably previously under the displacement limit for the emissons regulations and the regulations did not aply to them. The lower displacement limit now covers most 4 cylinder engines.

JD now offers the 4045 with common rail.

DavidM · Jan 8, 2017

Ski has given a good summary of who makes CR engines. But I want to challenge the premise that this whole thread is based. That is that common rail engines allow them to successfully be operated at light loads.

Let me paraphrase Tony Athens for the umpteenth time: "I have never seen a marine propulsion engine harmed by running at light load". He first said this before CR engines existed in the marine world.

Yes, I do believe that CR helps an engine to run at light load, but it isn't essential. CR pushes fuel through the injector tip at thousands of psi, not the hundreds (anyone know what it really is?) of mechanical engines so the fuel droplets are much smaller. Also some CR systems with piezo injectors operate with several pulses per combustion event so diesel is fed in a more controlled way into the combustion zone.

These features have had more benefits to emissions and quiet, smoke free running than on low load capability.

And CR does not have a big effect on efficiency. Ski posted an analysis he did on boatdiesel a few years ago comparing two Cummins engines of similar horsepowr, one a CR and one a modern mechanically injected engine- the QSC and the 6CTA I think. The mechanical engine was more efficient at some rpm/load ranges than the CR.

David

BandB · Jan 8, 2017

BIG CAT said:
The use of common rail fuel systems varies from engine to engine and from one mfg to another. Cat only has 3 engines that use common rail fuel systems. Most all the others use cam shaft actuation with electronic control.

It's by manufacturer and size. MTU was the leader introducing them as standard on their 4000 series in 1996. With most manufacturers they started on the larger engines as the smaller engines were not subject yet to the same requirements.

All CAT Tier 4 engines will be common rail.

Tony Athens · Jan 8, 2017

Low Speed Running

BandB said:
It's by manufacturer and size. MTU was the leader introducing them as standard on their 4000 series in 1996. With most manufacturers they started on the larger engines as the smaller engines were not subject yet to the same requirements.

All CAT Tier 4 engines will be common rail.

My direct experience with CR engines ( since early 2005-ish) leads me to believe that they indeed do better than mechanical engines running at low power settings in relation to there max power ratings or HP used per liter of displacement..

The reason is simple--Each RPM/load setting can be better optimized as to all the things that affect proper combustion.. On a mechanical engine, all you can do is basically set the pump to maximum power efficiently and everything else is a best compromise.. Luckily mechanical fuel injection is well seasoned as to design and as noted, CR engines do not always show a better BSFC in many cases, but not all.... Recent advances in ECM design
has let to some decent BSFC efficiently gains in the mid-range HP power settings on the Cummins products, most notably the QSL9 and the 6.7 Tier 3 products.

Long term cruising at 10-15 HP per liter seems to have zero negative effects as I now have plenty of these engines in the field will well over 15000 hours and at least a have about dozen at over 20,000 hours now. Of course, some of these boats had mechanical engine that went 20,000 hours++at low power setting to in the 10 years before and they came out running good..

Time will tell, but so far so good.

Tony

BIG CAT · Jan 8, 2017

djmarchand said:
Ski has given a good summary of who makes CR engines. But I want to challenge the premise that this whole thread is based. That is that common rail engines allow them to successfully be operated at light loads.

Let me paraphrase Tony Athens for the umpteenth time: "I have never seen a marine propulsion engine harmed by running at light load". He first said this before CR engines existed in the marine world.

Yes, I do believe that CR helps an engine to run at light load, but it isn't essential. CR pushes fuel through the injector tip at thousands of psi, not the hundreds (anyone know what it really is?) of mechanical engines so the fuel droplets are much smaller. Also some CR systems with piezo injectors operate with several pulses per combustion event so diesel is fed in a more controlled way into the combustion zone.

These features have had more benefits to emissions and quiet, smoke free running than on low load capability.

And CR does not have a big effect on efficiency. Ski posted an analysis he did on boatdiesel a few years ago comparing two Cummins engines of similar horsepowr, one a CR and one a modern mechanically injected engine- the QSC and the 6CTA I think. The mechanical engine was more efficient at some rpm/load ranges than the CR.

David

as far as injection psi. its could be as low as 2k for a old pre-combustion chamber fuel system to 28k for the c175. the c175 is the only large common rail engine cat makes as of right now. the other 2 are the c4.4 and c7.1 and the top out at around 14k psi.

as for running at light loads. the only issue that typicality happens is slobbering. most all of the new(last 5 years) engines below the 3500 series have very little issues with slobber. the old stuff was a different story. the ring pkg(keystone's) didn't seal well below about 30% load. in a boat you probably would be running at or above that mark most time. but with standby generators we see it a lot. the 3304 and 3306 were notorious for high oil consumption we ran with light or no load. but if you loaded them up good and put some heat in the hole they had a normal amount of consumption .

BIG CAT · Jan 8, 2017

BandB said:
It's by manufacturer and size. MTU was the leader introducing them as standard on their 4000 series in 1996. With most manufacturers they started on the larger engines as the smaller engines were not subject yet to the same requirements.

All CAT Tier 4 engines will be common rail.

there are tier 4 final and tier 4 interim engine's out right now that are not common rail. they will remain that way for the foreseeable future. cat is working on common rail for some engine's but not all. my hope is trump can pull back the epa regulations to allow mfg time to develop the systems before they hit the market. imo the tech is not where it needs to be from a reliability and cost effective stand point.

Tony Athens · Jan 8, 2017

Marine emissions

Just an FYI............ This forum and thread is talking about MARINE propulsion engines in sizes applicable to boats generally in the 20-100 ft range, with 95++% of them in the 30-45Ft range. Tier 4I or Tier 4 final IS NOT applicable to any marine propulsion engines in this size range.

Let's not confuse what this is about with engine designs or emission certifications that are not part of what this is about. ------------MARINE CERTIFICATIONS for EPA Category 1 propulsion engines.

Tony

markpierce · Jan 8, 2017

Common rail? Never heard of it before except when wiring my model railroad (operating on two rails) in the 1960s in 12-volt.

eyschulman · Jan 8, 2017

I have had 4 seasons experience with twin CR JD 6068 at 330Hp rating. Most of the time they are run at low loads. I have even gone one step farther by under propping and at max rpm get no more than 80% load. The boat runs sweet with zero smoke at all speeds up to 19K+ and I have no worries about over loading. I consider my actions as a form downgrading the engines from recreational type 4 rating to something less without the chip. I know most on this site will not be dealing with CR engines but for those looking at boats with them I am with Tony Athens and tell you to ignore some of the old school negative hearsay. As a teen ager I was a hot rodder and it is plainly apparent to me that almost any family car with modern electronic motors run so much better than what I used to play with and CR appears to be a positive improvement.

twistedtree · Jan 8, 2017

I've had nothing but great results from CR engines. They start right up, run clear all the time, minimal smell, quieter, smoother.... what's not to like.

My main is common rail (JD 6090), and the wing is not (JD 4045) with different tier ratings. I was confused why one engine needed to meet the then-newer EPA spec (I don't recall which one, but I think tier III), and the other didn't. So I dug into the requirements and its phase-in was based on the HP/liter rating on the engine. So higher output engines, as in higher hp/liter had to meet the new regs first, followed by lower output. This generally translated into pleasure rated engines first, and continuous duty engines later. My 6090 triggered the requirements at around 35hp/liter, but the 4045 didn't at just under 20hp/liter, hence the difference.

keb · Jan 9, 2017

Thanks for all of the great responses, that helped a lot. Now another diesel newbie question.... what constitutes too low of hours of usage? Say for example there is a 10 yr old diesel boat for sale and it only has been run 300-400 hours? I was originally concerned about too many hours, but learned here and elsewhere that a well cared for diesel engine can go for 10's of thousands of hours. At what level would you be worried about too little usage? Or would you? Would you also be concerned about a boat that has been on the hard for a couple of years?

BandB · Jan 9, 2017

keb said:
Thanks for all of the great responses, that helped a lot. Now another diesel newbie question.... what constitutes too low of hours of usage? Say for example there is a 10 yr old diesel boat for sale and it only has been run 300-400 hours? I was originally concerned about too many hours, but learned here and elsewhere that a well cared for diesel engine can go for 10's of thousands of hours. At what level would you be worried about too little usage? Or would you? Would you also be concerned about a boat that has been on the hard for a couple of years?

Yes, I'd be concerned. Would I automatically reject it? No. Each boat, each engine, must stand on it's on. Hours isn't going to tell you if it was abused or neglected, if maintenance was ignored. You need to know more and then ultimately you need to find out it's current condition, through sea trial and survey. I've known people who didn't find time to use their boats but mantained them very well, had them serviced a couple of times a year. I knew one man who bought a new boat, ran it twice, stored in in a dry storage building, had it winterized, and three years later figured out maybe he didn't need it and sold it. It was basically a new boat at a price depreciated three years. The dealer even turned away a sale by telling a future buyer about it and telling them they'd be getting as good as the boat on his floor at much less. I've also known boats pulled out of the water, never winterized, oil never changed, left half full of gas, and in unprotected storage. Someone then bought one like that I knew on the owner's assurance it ran fine last time he used it. Well, both engines had to be replaced as a start. We tried to warn the buyer but he just wouldn't listen, was so thrilled with the low hours.

North Baltic sea · Jan 9, 2017

Tony Athens said:
My direct experience with CR engines ( since early 2005-ish) leads me to believe that they indeed do better than mechanical engines running at low power settings in relation to there max power ratings or HP used per liter of displacement..

The reason is simple--Each RPM/load setting can be better optimized as to all the things that affect proper combustion.. On a mechanical engine, all you can do is basically set the pump to maximum power efficiently and everything else is a best compromise.. Luckily mechanical fuel injection is well seasoned as to design and as noted, CR engines do not always show a better BSFC in many cases, but not all.... Recent advances in ECM design
has let to some decent BSFC efficiently gains in the mid-range HP power settings on the Cummins products, most notably the QSL9 and the 6.7 Tier 3 products.

Long term cruising at 10-15 HP per liter seems to have zero negative effects as I now have plenty of these engines in the field will well over 15000 hours and at least a have about dozen at over 20,000 hours now. Of course, some of these boats had mechanical engine that went 20,000 hours++at low power setting to in the 10 years before and they came out running good..

Time will tell, but so far so good.

Tony

Hi Tony,

I understand that new types of engines such as CM qsb to drive a long day at low load there is no need to run the engine clean for half an hour at high load, but they do not suffer from carbon, glazing, etc?

BandB · Jan 9, 2017

North Baltic sea said:
Hi Tony,

I understand that new types of engines such as CM qsb to drive a long day at low load there is no need to run the engine clean for half an hour at high load, but they do not suffer from carbon, glazing, etc?

While like hearing his opinion, but we don't nor do our engineers, go that far. We still feel varying speeds and occasionally running at higher loads to be beneficial. We wouldn't run at 20% load 100% of the time, as we'd mix at least brief periods of higher loads. However, the glazing issues of the past are gone. In our opinion it's a matter of degrees. It's also the specifications of the specific engine. If it's designed for continuous use vs designed for high speed and lighter use, then that impacts the answer. Most manufacturers have many different versions of the same underlying engine.

Similarly, all those warnings you must run generators at least at 50% load are outdated. I don't know a single generator manufacturer today that says that. More typically they have an ideal target range of something like 30-70% with occasional use under or over acceptable.

IRENE · Jan 9, 2017

Ski in NC said:
Volvo D4 and D6 have been out for several years, not sure when exactly. Also common rail.

IRENE has a Volvo Penta D4-260 A-B, and she is a 2006 model.

She was 9 years old with only 80 hours on her when we purchased her. This was not a good thing in our case as it has an early version of this power package from VP. Most of the maintenance requirements we experienced were due to design "corrections" by Volvo Penta, such as updated steering cylinders, idler pulleys, etc. Fortunately these issues were known and fairly easy to deal with immediately.

Fletcher500 · Jan 9, 2017

Our boat is a planer, but we run it like a trawler most of the time.

She has two D6, common rail. As noted by others, starts up easy, burns very clean, environmentally friendlier, and no issues so far.

I also thought cylinder glazing may be an issue if running on low loads, so I would throttle up at least once during every outing for about 10-15 mins, but it sounds like that is not an issue anymore with this new technology per Tony.

OP - good thread. A guy in my marina bought a very large Mikelson SF 2 years ago with big Cats. Same deal as BB described. Older person initially bought it, fished it a few times, but spent the rest of the time at the dock. The new owner had to chase some gremlins getting the engines back to spec, the major item being the raw water system, but overall it seems to have worked out for him.

North Baltic sea · Jan 9, 2017

BandB said:
While like hearing his opinion, but we don't nor do our engineers, go that far. We still feel varying speeds and occasionally running at higher loads to be beneficial. We wouldn't run at 20% load 100% of the time, as we'd mix at least brief periods of higher loads. However, the glazing issues of the past are gone. In our opinion it's a matter of degrees. It's also the specifications of the specific engine. If it's designed for continuous use vs designed for high speed and lighter use, then that impacts the answer. Most manufacturers have many different versions of the same underlying engine.

Similarly, all those warnings you must run generators at least at 50% load are outdated. I don't know a single generator manufacturer today that says that. More typically they have an ideal target range of something like 30-70% with occasional use under or over acceptable.

generator owner's manual recommends the same what you say.

I have read Cummins QSB my manual and there does not say anything else than the max rounds.

a new engine driving refers to driving a wide range of different loads. this is certainly the best later on, but I have not seen Cummins says to do so. the boat is still new to me so I have not pushed him even more than about 170 hours and about 1,200 nautical miles in a few months half nautical mails of 15 knots, ie the engine quite a heavy load of about 75-80%. the coming season to drive more slowly and fuel-efficient because it is really expensive here..

RCook · Jan 9, 2017

Our Volvo KAD44P is not common-rail, but it is electronically controlled, the first of its kind. It was built in late 1997, close to the same time as our 1998 (also first-year) electronically-controlled Cummins ISB pickup diesel.

Our experience leads me to believe that electronically-controlled boat engines provide much better and cleaner low-power operation than mechanical ones, even if they are not common-rail.

In its first few years, we used to run it up to planing cruise power after hours of low power operation. After it was thoroughly broken in, it did not seem to need that unless we had been idling extensively (fishing), and even then not every time.

Newer generation engines

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