Common rail vs direct diesel injection

[NBs]

I think this contrasting direct vs CR depends on your needs and your boat so the answer is impossible.

In my case, my "trawler" I'm happy Cummins QSB common rail, because I can run unlimited time +800 rmp low load and the machine does not get damaged carbons, glazing cylinder, etc, the coolant and oil temperatures are ok. My Cummins is raiting max 3000 rmp -200rmp longer periods of driving . This is not the old school diesel capable?

NBs

 

[jfm]

this contrasting direct vs CR

It's a long time since there has been a thread full of such nonsense. You can contrast direct vs indirect injection. You can contrast CR vs unit injection. And you can contrast electronically governed versus mechanically governed.

But you cannot meaningfully contrast direct injection with CR. Indeed, your Cummins is BOTH direct injection AND common rail.

 

[Portofino]

It's a long time since there has been a thread full of such nonsense. You can contrast direct vs indirect injection. You can contrast CR vs unit injection. And you can contrast electronically governed versus mechanically governed.

But you cannot meaningfully contrast direct injection with CR. Indeed, your Cummins is BOTH direct injection AND common rail.

I think he means and the Op initially CR vs none CR .
A new today’s Vs an older tech yesterday s Vs .

Tbo not sure if any modern builders fit none CR these days - driven by various emissions regs / laws ? In the markets they punt them ?

But fitting a CR into a supposedly rufty tufty go any where , Artic to Antarctic and back triple redundancies built into every system etc —— is a huge Achilles heal ,esp if only 1

Bring back a Gardner 6 LXB or such like :encouragement:

 

[Portofino]

I think this contrasting direct vs CR depends on your needs and your boat so the answer is impossible.

In my case, my "trawler" I'm happy Cummins QSB common rail, because I can run unlimited time +800 rmp low load and the machine does not get damaged carbons, glazing cylinder, etc, the coolant and oil temperatures are ok. My Cummins is raiting max 3000 rmp -200rmp longer periods of driving . This is not the old school diesel capable?

NBs

I,am not convinced your warm blanket you have wrapped your self in regarding low load running circa 800 rpm is gonna last .
How many hours have you got on them now ?

With regards to matching engines to boat to useage that’s been done for you and you should try to follow that .
It’s all about cylinder temps / pressures with diesels , water jacket or oil temps are a side show and low down in the pecking order .

Let me give you and example of matching boat to useage to engines .
Take a Sunseeker Predator 108, std spec was twin MTU 2400 Hp or somthing ? Cruise near 30 knots at 2000 rpm .
2000 rpm the correct cylinder temps / peassurs for longevity .
A triple for mid thirties nudging forty knots .
Both boats could do D speeds @ the usual water line length say 12-14 knots with this 108 , save fuel , take your time , relax in the hot sun etc ,have fun navigating etc etc .
A guy wanted ( 1 y sabbatical) to go round the med slowly , thinking of fuel burn the std spec at 2000 rpm looking at 1000 L / h —- bit of a think not sure I want to blow £1 M on fuel over the year hmmm what can we do , ?
The Factory built it with matching useage / speed / engines with a pair of John Deere’s
He did something like approaching 2000 hrs in that year , but at D speed
Of course the JD ,s 6 cylinder - cylinder temps / pressure were spot on @ 2300 rpm all day and sipped fuel compared to two or three MTU V 16. ,s going full chat ,or even 800 rpm point is this the MTU,s would not have lasted 2000 hrs @ some eco 800 rpm .

 

[jfm]

I think he means and the Op initially CR vs none CR .
A new today’s Vs an older tech yesterday s Vs .

Tbo not sure if any modern builders fit none CR these days - driven by various emissions regs / laws ? In the markets they punt them ?

Crikey, the bolx continues.

Sure, let's compare CR vs non CR is you want to have a nonsensical discussion. I assume/hope that the comparison is AOTBE, so we're comparing CR vs unit injection, right? Those being the only two widely used technologies to pressurise fuel. FFS.

Your comment that CR vs non CR is relevant to emissions is also total bolx. The means by which you pressurise fuel has absolutely nothing to do with emissions and there are plenty of Tier 3 compliant engines that are non CR (Cat C32 being but one example - indeed it even comes in Tier 4 compliant version).

As I say, it's been a long time since there has been a thread so full of nonsense.

 

[NBs]

I,am not convinced your warm blanket you have wrapped your self in regarding low load running circa 800 rpm is gonna last .
How many hours have you got on them now ?

With regards to matching engines to boat to useage that’s been done for you and you should try to follow that .
It’s all about cylinder temps / pressures with diesels , water jacket or oil temps are a side show and low down in the pecking order .

Let me give you and example of matching boat to useage to engines .
Take a Sunseeker Predator 108, std spec was twin MTU 2400 Hp or somthing ? Cruise near 30 knots at 2000 rpm .
2000 rpm the correct cylinder temps / peassurs for longevity .
A triple for mid thirties nudging forty knots .
Both boats could do D speeds @ the usual water line length say 12-14 knots with this 108 , save fuel , take your time , relax in the hot sun etc ,have fun navigating etc etc .
A guy wanted ( 1 y sabbatical) to go round the med slowly , thinking of fuel burn the std spec at 2000 rpm looking at 1000 L / h —- bit of a think not sure I want to blow £1 M on fuel over the year hmmm what can we do , ?
The Factory built it with matching useage / speed / engines with a pair of John Deere’s
He did something like approaching 2000 hrs in that year , but at D speed
Of course the JD ,s 6 cylinder - cylinder temps / pressure were spot on @ 2300 rpm all day and sipped fuel compared to two or three MTU V 16. ,s going full chat ,or even 800 rpm point is this the MTU,s would not have lasted 2000 hrs @ some eco 800 rpm .

Hi,

950 hours about 90% 850-1300 rmp and 10% 2700 rmp.

I have asked this thing Cummins US and the manufacturer is responsible to me very clearly say, here's my question, and their answer to me.

RE: Low rmp vs life time qsb 5.9 marine [SR#:1-54043967600]

Xxxx,
This is fine for our engines. It is not suggested to Idle (650-750rpm) for long periods. Generally speaking, you can idle for about 20 minutes or so at this range and be okay. If you plan to idle longer than 20 minutes or so it is suggested that you ramp up your RPM to about 800-1000. Working the engine under a light load/rpm is fine. This is not uncommon for some our engines (like Generators which normally work at 1800 RPM or less) and will not cause any undue harm.
Thank you for contacting Cummins.
Katelyn
Customer Care Representative
If we have misunderstood the information in your communication or you have additional questions please feel free to respond to our support staff by e-mailing support.engineparts@cummins.com or 1-866-CUMMINS (286-6467). If you are located outside of North America, you can reach us at 1-615-871-5500.
Visit us at www.cummins.com or www.cumminsengines.com
-------Original Message-------
From: sea.way@outlook.com
To: powermaster@cummins.com
Cc:
Subject: Low rmp vs life time qsb 5.9 marine


External Sender


Hi,

I have a Cummins 5.9 qsb marine engine 2009 and it reaches max rmp 3065 which is perfect my Nordic Tug 37.

I have read a lot of conflicting opinions on the engine to run at low rmp a long time, because the machine may damage the carbon and etc. Some say it's ok to run this type engine at low rmp if the coolant remains in the correct slot.

The time i run my engine is most often 850-1300 rpm since the boat is most economical in this rmp area and temperature is ok. Cummins runs fine and does not smoke any, exhaust pipe mouth environment does not show any black carbon.

What is the manufacturer's view of low load low rmp almost always, whether it is ok or damaging the engine?

It would be great to have an expert answer, all the web instead of rumors.

Best regards
Xxx xxxxxx
Xxxxxxxxxx


NBs

 

[NBs]

It's a long time since there has been a thread full of such nonsense. You can contrast direct vs indirect injection. You can contrast CR vs unit injection. And you can contrast electronically governed versus mechanically governed.

But you cannot meaningfully contrast direct injection with CR. Indeed, your Cummins is BOTH direct injection AND common rail.

Hi

Yes, but my old boat engines is twins VP KAD44 EDC and direct injektions but not common rail engines, That's why the parable to me makes sense. In these engines, a manufacturer with a clear message do not drive the machine for long periods of time without turbo or super scharger ie below about 1700 rmp

NBs
(Sorry, my possible word choices and bad English.)

 

[Jegs]

Hi

Yes, but my old boat engines is twins VP KAD44 EDC and direct injektions but not common rail engines, That's why the parable to me makes sense. In these engines, a manufacturer with a clear message do not drive the machine for long periods of time without turbo or super scharger ie below about 1700 rmp

NBs
(Sorry, my possible word choices and bad English.)

Surely the supercharger works at far fewer revs than 1,700?

ATB,

John G

 

[MapisM]

Yes, but my old boat engines is twins VP KAD44 EDC and direct injektions but not common rail engines, That's why the parable to me makes sense. In these engines, a manufacturer with a clear message do not drive the machine for long periods of time without turbo or super scharger ie below about 1700 rmp

Nope NBs, I'm afraid that it's still an apples and oranges comparison.
VP recommendation has absolutely zero to see with the fact that the KAD44 are not CR engines.
It's instead driven by the fact that they are high revving engines (3600, IIRC?) with both a compressor and a turbine.
Before the KAD44, they made the KAD42 and the KAD43 which were not even electronically controlled, but based on the same logic. The block was discontinued after the 44, but if they would have used the same architecture for a common rail KAD45, the recommendation would have still been the same, AOTBE.

 

[NBs]

Surely the supercharger works at far fewer revs than 1,700?

ATB,

John G

Hi,

Sorry, did you mean Super charger starts with smaller rmp or ...? My rmp range was exactly 1650-2650rmp and switched off as the turbo pressures are sufficient to continue up to 3900rmp max. A fine engine for planig Hull on a boat that usually drives over Hull speed. Know the boat where KAD44 has done now +4500 hours, it's a good achievement for a high power engine 3,6 displacement.

NBs

 

[petem]

Know the boat where KAD44 has done now +4500 hours, it's a good achievement for a high power engine 3,6 displacement.

That's good to know (as long as it's not like "Trigger's Broom") .

At best I suspect it's had a few turbos, superchargers, intercoolers, new valve nozzles, oil coolers and heaven knows how much spent on the legs!

 

[jfm]

my old boat engines is ... direct injektions but not common rail engines, That's why the parable to me makes sense.

This is surreal. My engines have direct injection but not green paint. So shall we do a thread comparing direct injection vs green paint? Would that also make sense to you?

 

[jfm]

Nope NBs, I'm afraid that it's still an apples and oranges comparison.
VP recommendation has absolutely zero to see with the fact that the KAD44 are not CR engines.

Exactly. (And don't be too tough on the poor apples and oranges - at least they are both fruits )

 

[NBs]

Exactly. (And don't be too tough on the poor apples and oranges - at least they are both fruits )

If you have only money, you can be very poor, do not you? have I claimed the Kad CR engine, I ask you to orange or other fruit witty answer JFM?

Apparently, this was just the English world of humor ... like the hyacint Bucket BBC production:sleeping:?

 

[MapisM]

NBs, being a non-native EN speaker myself, I can see why some of what was said could be due to language misunderstanding.
On top of that, I see that you are very new (but still welcome anyway! ) to the asylum.
But I can assure you that even if some jfm comments can be seen as provocative, I believe that all he is trying to say is that in this thread the confusion on the comparison of technical alternatives has been amazing - and right from the first post, btw, which wasn't made by yourself!

Let me put it this way - there are some choices which are mutually excluding:
1) Direct OR indirect injection
2) Common rail OR unit injectors
3) Mechanical OR electronic governor

Therefore, 1, 2 and 3 are all meaningful comparisons.
But if we take any of the (1) alternatives, and we compare it with any of the (2) or (3) alternatives, the comparison is not meaningful anymore.
In fact, you can have (and indeed there are!) direct injection engines with either common rail or unit injectors, and also mechanical or electronically controlled.
And also a KAD engine with common rail could actually be built, because the supercharger+turbo concept doesn't restrict in any way the choice of the injection system.
The reason why a common rail KAD45 doesn't exist is simply that VP never built it, not that it would be impossible... :encouragement:

 

[Assassin]

So, is that apple green paint or orange green paint?