Engine Questions - More to come...

In the recreational sportfishes, CAT says you can run the C18 an hour a day at 100%. Or run it at 80% load all day long (which is what everyone does), but for example a sportfish that cruises at 80% load will do 31 knots, and top out at 36knots at 100% load.

Hi,

Don't know what you were looking for for 20 mins.

This was my first google attempt, It answers your 16V2000 Question in the first response.

http://www.google.co.uk/search?sour...s+a+16v2000+weigh&btnG=Google+Search&meta=lr=

Cat C 18- 1672 TO 1718 KG Dry

Cat C 32- 2548 TO 2632 KG Dry

C18 versus C30 in 2004 54 hatteras

Looking at buying a 54 hatteras (2004) this boat comes with Caterpilllar C-18 or C-30. I don't really need to fast I am happy cruising at 24 knts. Is it better to run a C-18 at 80-85% load or run a C30 at less load of 65-70%. I have heard that if you cruise a boat at lower load than recommended this is bad for engine.
Also what is the likely burn rate (GPH) of both these engines. I was told by a broker that the 54 hatteras with C-18 cats will run less bow high since these engines weigh much less than the C30. And because of this there is a large gain in efficiency with much less fuel burn. Anyone have any experience with a 54 hatteras with c-18 cats. Are these engines enough for the 54 hatteras wich is a heavy boat and tends to run bow high. Thanks in advance

http://www.adieselengine.com/new_page_1.htm

Heres a list of plenty of diesels to compare. They may be ballpark but if you arent willing to call the people at DD and ask them I would say ballpark is the best are going to get.

And to your response to Marmot there are some very smart people on this forum but I dont know too many of them who take the time to memorize specs. If you are looking for a recomendation on which engine to repower a yacht with the forums are great, but for specs on old diesels contact the mfr.

Best of luck,

Dan

Maybe it's more difficult for royalty ... I am just a peasant but managed to find:

Results 1 - 10 of about 2,350 for DD 12V-71 brochure. (0.18 seconds)

And the answer was in Result #1.

Hi,

I too am a commoner and it took a bit longer over here but did return a couple of hundred more results, like Marmot the answer was available in the first result even giving several gear options and weights.

Results 1 - 10 of about 2,570 for DD 12V-71 brochure.. (0.39 seconds)

Overfuel at low power settings?

The only thing that determines how much power a diesel produces is how much fuel it burns. If it gets more fuel it produces more power so it can't be "overfueled" at a low power setting ... it will just make more power unless it's out of gear then it will just idle faster.

A diesel can be "overfueled" at high power, it's called overloading (or charge air problems) and is normally recognized by black smoke.

If you meant that poor injection or combustion might result from long periods of low loading then thats a different story and really only applies to extended periods at very low power loading like at idling in gear. Slow running down at 25 or 30 percent load is not the end of the world as long as jacket water and oil temperatures are "in the green."

May or may not be true for all manufacturers, but everyone from Roger on down to the kid at the parts counter at Detroit Diesel knew not to run a boat right at the transition-to-plane point: major loading/lugging of the engines, turbos not offering much boost, lotsa black smoke...which usually occurred at ~1300-1400 RPM.
A serious shortening of the fuse.

A lot of the older mechanical engines will get very sooted up running at hull speed. Say 1000 rpm's or less for the older Detroits, Cats, MTU 12v183's etc. They also usually won't maintain water jacket temperature. The airboxes in the Detroits get wet with unburnt fuel. The problem is the injectors don't atomize the fuel properly at such a low fuel burn, say 3 gph at slow speeds versus 50 gph at cruise. After a day of slow speeds or trolling, these engines will expel all kinds of sooty smoke for a minute or two once you put them up to cruise rpm.

I have run a few 54' Hatteras SF's from 2004 to newer. All 3 of them have had the C30's and they are a great riding/running boat with the C30's. Terrific sea boat and dry, cut's through everything and never pounds. They all cruised around 33 knots- 34 knots at 80% load. I've heard they cruise at almost 30 knots with C18's but have never ridden on one.

It should be fine to run any of the newer CATS at say 1650rpm's all day. Efficiency ends up being the same though typically from what I've seen whether you run them at 1650rpms or 1950 rpms.......the Gallons per mile.

hatteras 54 with C-18

Thanks Capt J, does anyone on the forum have any experience running a 54 hatteras (2003-or newer) with Caterpillar C-18 ?

Also concerned about resale value with C-18 since most hatteras 54's are built with C-30.

Hi,

Can you please explain to everyone here how the rate of fuel burn has anything to do with Injector Atomisation?

The injectors are opened such a minute amount that they don't meter and/or flow the fuel properly at such a small percentage of fuel flow. The mechanical injectors do not spray an efficient flow pattern a lot of times when there is a very small load factor. They're not as precise.

With electronic injectors the computer changes how long they're open and it's more efficient and metered much better that way.

Hi,

May I suggest you take up the course as a Mechanics Helper that you referred another poster to.

With a mechanical Injection system in an older engine the duration of the injection is set mechanically, the distance the plunger in the fuel pump or injector in the case of Engines with a DD Type Injector is controlled by the lift of the Camshaft.

The time taken to open and close the Injector is the time it takes to push out the fuel charge in a pressure operated system.

Atomisation has nothing to do with the level of fuel burn. When rebuilding and testing Injectors in the workshop there is no burning cycle yet the Injector has to crack off ( open) at a certain pressure, it has to be able to hole pressure and the fuel has to atomise properly - there is no heat and fuel burn taking place here.

The reason why engines get sooty and injectors get fouled when running an engine at low load for extended periods is because there is insufficient stoichiometric air in the cylinders to facilitate complete combustion of the volume of fuel entering the cylinder, in time as a consequence of running like this there will be enough soot build up on the Nozzle Tip to interfere with atomisation. This has no bearing on the actual amount of fuel going to the Injector.

A stoichiometric mixture is when the correct ratio of oxygen to fuel exists so that all the fuel can be burned without leaving excess oxygen after combustion.

A diesel operates with excess air in all modes except at or beyond the "smoke point' which is when the charge air system can no longer provide sufficient air to burn all the fuel.

At low loads or at idle there is far more air than required to burn the fuel but that air also provides a heat sink for fuel that has begun to burn. It cools the process enough that fuel on the outside of the spray pattern is not completely burned. Only the surface of those fuel droplets burns and the center of the drops are converted to carbon and are exhausted as soot particles.

Mechanical injectors are also affected by the rate of pressure rise and fall during the injection period. At idle the pressure drops rapidly after opening and while the first part of the injection occurs at the proper pressure, by the time the period ends and the valve closes, fuel is not atomizing properly and this contributes to poor combustion and creation of soot. That is why common rail and electronic injection control has reduced this problem. The pressure remains high through the injection period to assure proper atomization, and the injector can be modulated to provide the best cylinder environment for better combustion.

None of these phenomena could ever be described as "overfueling" by any stretch of imagination.

Yeah, what he said.

C32 engines are too large for a 55-60 foot boat, they are also too heavy.
I have them in an 80' Fairline Squadron and they perform extremely well in that size.
For a 55-60 foot boat I would chose the MAN V12 1360CRM with 1360mhp each. If top speed is not an issue, I would then go with the MAN V10 1100CRM with 1100mhp each. You would still be cruising at around 23-24knots and top speeds of about 33-35knots. IMO the C18s with 1015mhp each will be a little underpowered for that size boat.