Engine Longevity

[Willallison]

Manufacturers of diesel engines usually rate motors according to how they're going to be used. Commercial, continuous, pleasure etc.

Does anyone have info regarding the expected life of engines when run at these ratings?
For eg a pleasure rated engine may be expected to run 5000 hrs. The same engine derated to commercial rating may be expected to go 20,000....etc

[badges65]

Hi,
it all usually comes down to who operates/maintains the engine, does he know anything about engines, their usage in marine conditions, and the way he operates the engine in given water conditions.
a good operator of an engine will give far many more hours life to an engine regardless of the type or rating of the engine..
don

[67-LS1]

The following are the rating guidelines published by Cummins.

Continuous Duty (CON)

Intended for continuous use in applications requiring uninterrupted service at full power. This rating is an ISO 3046 standard power rating.

Typical vessel applications include: oceangoing displacement hulls such as fishing trawlers, freighters, tugboats, bottom drag trawlers, and towboats.

Heavy Duty (HD)

Intended for continuous use in variable load applications where full power is limited to eight (8) hours out of every ten (10) hours of operation. Also, reduced power operations must be at or below 200 rpm of the maximum rated rpm. This is an ISO 3046 fuel stop power rating and is for applications that operate 5,000 hours per year or less.

Typical vessel applications include: displacement hull vessels such as mid-water trawlers, purse seiners, and towboats where frequent slowing is common and engine speed and load is stable. Also used in high speed vessels such as ferries and crewboats.

Medium Continuous Duty (MCD)

Intended for continuous use in variable load applications where full power is limited to six hours out of every twelve hours of operation. Also, reduced power operations must be at or below 200 rpm of the maximum rated rpm. This rating is an ISO 3046 fuel stop power rating and is for applications that operate less than 3,000 hours per year.

Typical vessel applications include: planing hull ferries, fishing boats designed for high speeds to and from fishing grounds, offshore service boats, and also (non-cargo) displacement hull yachts and short trip coastal freighters where engine load and speed are cyclical.

Intermittent Duty (INT)

Intended for intermittent use in variable load application where full power is limited to two hours out of every eight hours of operation. Also, reduced power operations must be at or below 200 rpm of the maximum rated rpm. This rating is an ISO 3046 fuel stop power rating and is for applications that operate less than 1,500 hours per year.

Typical vessel applications include: planing hulls such as customs, military and police vessels, charter and some fishing vessel applications.

High Output (HO)

Intended for use in variable load applications where full power is limited to 1 hour out of every 8 hours of operation. Also, reduced power must be at or below 200 rpm of the maximum rated rpm. This power rating is for pleasure / non-revenue generating applications that operate 300 hours per year or less.

Typical vessel applications include pleasure craft such as sportfishers, motoryachts, and cruisers.

BHP - ISO 8665 fuel stop power rating. Fuel 40 C (104 F).
Metric Horsepower - ISO 3046 fuel stop power rating. Fuel 25 C (77 F)

[Willallison]

Thanks for the input guys - I'm aware of the effect operators will have on engine life and the exerpt from Cummins displays exactly what I'm talking about. Alas it doesn't really answer my query.

When operated in accord with manufacturer recomendations, how long (operating hours) will an engine last?

I'll use the Cummins 555 as an example (it's old but they're the only figures I have to hand)
In it's naturally aspirated form this engine has a pleasure boat rating of 215hp @ 3000 rpm, (light duty is the same), and a continuous duty rating of 185hp @ 2800 rpm.

Now surely the continuous engine would last longer than the pleasure engine. And both would last longer than the turbo-charged variant with a pleasure rating of 270hp @ 3000 rpm.....
But how long?

[badges65]

Hi,
It still comes down to who is using the engine..
nobody i know has set up and engine and run it continuoulsy on a dyno til it craps out at the different settings. even then you could not experience what an engine does under working conditions.
I have rebuilt a commercial 12V71 after 20.000 hours in a trawler and the mains and big ends didnt need to be replaced, the only problem was that all the top rings of the pistons were completly burnt out. engine was still working okay but using abit more fuel..
no one will give you the true facts you are asking for as no one want to be responsible if the engine doesnt last that long!!!
don

[Willallison]

nobody i know has set up and engine and run it continuoulsy on a dyno til it craps out at the different settings

I would expect that every manufacturer has done exaclty that...

no one will give you the true facts you are asking for as no one want to be responsible if the engine doesnt last that long!!!

Now you may be on to something......