Car/boat engine life - how to calculate ???

[ulyden]

Where were you Latestarter when Allen launched their 5000 series. 25.5 bar bmep for base load? (Not at pleasure engine)

Remember 10 years ago when I bough my first boat. It had a 170hp 6 cyl Volvo penta engine witch could consume amazing 60l/h giving the boat 32knots.

I was looking for a simple and reliable but not so durable engine for my boat. I was planning to by a cheap car diesel engine and if it lasted 500+h it was ok. (10 year for me).

At that time 2 and 2.5liters were maximum size and I needed more than 100hp.

At that time I was travelling a lot in north Europe. All these light vans that were running 130km/h up and down the highway (autobahn). These engines are running at rated speed (4000) all day working for freight companys. So if the car could do 200 000km in that state that meant 200 000km in 130km/h or 1500h. Plenty for me!

(I know that some of these ligt vans are "under propped " but still its amasing high load )

My engine is rated 85hp from the factory. Im pulling out 130hp at maximum and 90 to 100hp at crusing speed of 3500-3600rpm. 310h no problems.
.

 

[Latestarter1]

Where were you Latestarter when Allen launched their 5000 series. 25.5 bar bmep for base load? (Not at pleasure engine)

Remember 10 years ago when I bough my first boat. It had a 170hp 6 cyl Volvo penta engine witch could consume amazing 60l/h giving the boat 32knots.

I was looking for a simple and reliable but not so durable engine for my boat. I was planning to by a cheap car diesel engine and if it lasted 500+h it was ok. (10 year for me).

At that time 2 and 2.5liters were maximum size and I needed more than 100hp.

At that time I was travelling a lot in north Europe. All these light vans that were running 130km/h up and down the highway (autobahn). These engines are running at rated speed (4000) all day working for freight companys. So if the car could do 200 000km in that state that meant 200 000km in 130km/h or 1500h. Plenty for me!

(I know that some of these ligt vans are "under propped " but still its amasing high load )

My engine is rated 85hp from the factory. Im pulling out 130hp at maximum and 90 to 100hp at crusing speed of 3500-3600rpm. 310h no problems.
.

I am no medium speed engine man, totally different can of beans, but didn't the Allen become another great British flop which caused Rolls Royce the owners of Allen to sue the backside off Ricardo before closing the whole company down?

LDA (Light Duty Automotive) engines running on motorway autobahn pedal to the metal are mainly pushing air, actual lengine load factors are in the order of 30%. Load factor increases when pulling a grade in transient manner until driver puts a gear shift in then load factor falls as a result. This is EXACTY the problem with using LDA engines with VG turbo machinery in marine applications, unlike your autobahn load factor the engines spend much time just above peak torque making loads of soot which clogs swing vanes. Until industry adops the more expensive stepper motor controlled sliding nozzle turbochargers I refuse to accept that VGT is a good solution for marine applications regardless of engine color.

Moving away from LDA engines to more mid range 5-7 liter high speed diesel as well as heavier duty 8-13 liter engines the current engine design technology seems to allow an upper end of about 35 HP per litre for true continuous duty.

The factors I quoted in earlier post did not fit some cases therefore it is perhaps better to use factor in the range of 7,000-15000 gallons of fuel burned per liter of displacement before we are at life to overhaul. Big range I know but some engines have more meat on the bone than others.

Now you ask, where did I come up with 35HP per litre? If you search through data sheets all of the latest high tech diesels made by MTU / Detroit, CAT, CUMMINS, VOLVO, MAN, SCANIA, IVECO, JOHN DEERE, MITSUBISHI, etc., that actually go after the workboat market and really understands what continuous duty means, you'll find that the upper limit is about 35HP per liter.

So, what could all of this really mean to people in the recreational marine market when we talk about engines that are rated to 60 - 80+ hp per liter? Diesel engines in recreational ratings which come with all sorts of caviats regarding time at WOT and maximum annual hours. However it is performance sells the product on sea trial day. In reality most of us cannont afford to spend that much time running at the top end.

Therefore continuous duty for recreational use represents a maximum load factor in the region 30 to 50% as I stated at the beginning.

 

[MapisM]

Now you ask, where did I come up with 35HP per litre? If you search through data sheets all of the latest high tech diesels made by MTU / Detroit, CAT, CUMMINS, VOLVO, MAN, SCANIA, IVECO, JOHN DEERE, MITSUBISHI, etc., that actually go after the workboat market and really understands what continuous duty means, you'll find that the upper limit is about 35HP per liter.

Interesting reading, LS1.
I don't need to check the specs sheet for my 15 years old Cat 3116, 'cause I considered to de-tune them when I originally bought the boat, since their max rated power is totally useless on my heavy displacement hull.
So, I remember by heart that the continuous duty version made 230hp @ 2400 RPM (350 @ 2800 when pleasure rated).
Being 6.6 litres, that makes, guess what? 34.9hp per litre...!

 

[ulyden]

Well LS1 the allen 5000 thing was a joke. (Just pointing out that there were people on the island that knew this was a bad idea)

Still im confused about a LT crusing from munich to kiel in 130km/h at 4000 revs have a load factor of 30%. Assuming a front area of 4m^3 and a CD of 0.45 the air resistance is 1.43kn giving a air resistance of 51kw at 130km/h.

When the engine power is 62kw and there are some rolling resistance and some loss in powertrain its hard to believe a load factor of 30%.

I remember in 1986 Saab took 3 cars from production line and ran them at full speed for 8 days 100 000km by a average speed of 212km/h. The car was a 9000 turbo with 175hp 2litre engine (87hp pr litre).

In 1990 i was working with MTU 396 TB84 series engines. Rating 2040kw continues DS.Volume (3.96 *16= 63.36) Power pr liter 2775hp/63.36= 43.85hp/liter

These ships still runs today!

 

[Latestarter1]

Well LS1 the allen 5000 thing was a joke. (Just pointing out that there were people on the island that knew this was a bad idea)

Still im confused about a LT crusing from munich to kiel in 130km/h at 4000 revs have a load factor of 30%. Assuming a front area of 4m^3 and a CD of 0.45 the air resistance is 1.43kn giving a air resistance of 51kw at 130km/h.

When the engine power is 62kw and there are some rolling resistance and some loss in powertrain its hard to believe a load factor of 30%.

I remember in 1986 Saab took 3 cars from production line and ran them at full speed for 8 days 100 000km by a average speed of 212km/h. The car was a 9000 turbo with 175hp 2litre engine (87hp pr litre).

In 1990 i was working with MTU 396 TB84 series engines. Rating 2040kw continues DS.Volume (3.96 *16= 63.36) Power pr liter 2775hp/63.36= 43.85hp/liter

These ships still runs today!

Uliden,

I respect you as a professional engineer, however I believe my #'s, remember DCM work will give you average % engine load and even the most ardous road going duty cycle operation is still transient not truly continuous. A propeller is a real ugly and unforgiving means of transmitting power which makes life FAR harder in marine applications.

MTU 396 range has a rather broad range of continuous ratings, from 2000 rpm down to 1600 rpm. The only the only one TRUE continuous rating is 1A (Unrestricted continuous operation).

If we take 12V396 1020 kW @ 1,600 rpm rating 1A. 1020 kW = 1,368 Hp. MTU 396's are a 4 liter/cyl modular motor therefore the 12 jug version is about 48 liters, which in my book comes out at 28.5 Hp/liter in my book. I stand by my 35 Hp/liter rule.

Never had any direct experience with MTU 396, however much talk of crankshaft breakage in either the 8V or 12V many years ago. Reliability issue, allegedly put down by MTU as guess what? Operation outside defined duty cycle.

MTU 396 and later models do have major drawback when operating in competition with CAT 3506 and Cummins QSK motors in Rhine barges. All have similar 20/25K hour total life to overhaul, however MTU requires mandatory and expensive mid life cylinder head, injector, and turbocharger change out at their half life, which tends to count against them in the total durability stakes.

We are now at risk of boring or confusing the OP brainless.

Can we agee that we will never take any diesel engine to wear out in defined pleasure operation (durabilty). However engines will be killed off long before their time due to a number of causes, my pet ones are:

Overloading by operation outside defined performance envelope. Builders and owners Cavalier approach to dangers of over propping.

SWAC charge air cooler maintainence. Rarely appears on service shedules and not on the radar of many so called servicing professionals. Remember the recent post where owner was considering ripping injectors out of one motor and switching them to the other!!! Zero consideration given to servicing SWAC.

Damage to injection system as well as base motor with half assed penny pinching approach to fuel filteration.

 

[ulyden]

I was looking in the bible today and you have amasingly right. Most diesel engines sold for continues unrestricted service had about 35hp/liter.

Sorry I never calculates hp/liter but i know some gas engines are produsing 47hp/l
(Jenbacher 624 with to stage turbocharging. 190/220 24 syl 4500kw)
Think GE made a CR locomotive engine out of this! Don't remember the diesel rating.

Should not say much about MTU but there were issues then and there is now.
And you are right the engines i rememberd were 1DS rating and not 1A.

They got a long life after som trouble with cold water and wheather. The engines i worked with where modified.