Coverting Diesel Engin into Dual Fuel(Diesel/HFO)

[Jake]

Hi,
I want to build a landing craft vessel with loading capacity of 750Tons.
It require 2 x 600BHP @ 1800rpm engine, thus it is impossible to find an engine running with HFO at this size.
Is there any way though to mix a use of MDO and HFO to a 400 - 600BHP engine?
Thank you for your advise.

[D Winsor]

The short answer to you question is no. Even if were possible the cost of converting small high speed engines which are basically truck engines to burn heavy fuel, combined with much higher maintenance costs plus the addition of the equipment required to clean and heat the fuel to maintain the proper viscosity for injection would outweigh any savings in fuel costs. Especially in a vessel like a landing craft that would not necessarily be on many long extended voyages.
The only engines I know of that ran at that RPM in that horsepower range that were built with the capacity to run on blended fuels are the Caterpillar 3500 series engines. However as far as I know there were many issues with fuel injectors and engine failures caused by Lube Oil Contamination. As a result Caterpillar no longer recommends using blended fuels in these engines.

[Merlyn]

The older diesels ( pre common rail ) of that size will run on almost anything that will pass through the filters.
I know many years ago in U.K. When people over here to duck the tax on white diesel would run that h.p. on paraffin with a drop of lube oil added for years ok, no problems.
Exhaust smell was very different and you could tell what the fuel was by the very low smoke meter reading when taken.
Still some folks here who made their own fueloil out of old cooking oils etc by cobbling up homemade kits.
Worked out 65% cheaper per gallon and never let them down, ever.
We have a propane/butane gas bottle at work and if you have a non starter by administering it into the intake to see if it runs you can tell instantly if the non running defect is a non fuelling issue.
So it will run on that.
Incidentally when seeking out a misfire/ lack of power defect by "gassing " the engine ( with a blowtorch administered all around the inlet manifold and joints ) you can tell if there is an induction leak present in porous manifolds and leaky joints by virtue of the fact that the rpm instantly increases i.e. It revs up on its own pin pointing the exact location of the leak.
Lots of engines over here running on gas, even some on human waste.
HFO mixing with LFO might to some degree require heating up via maybe a 24volt element jobby and when the engine is up to temp. run the mixture through a engine water heater exchanger device? ( tubestack one )
Just a thought.

[Merlyn]

Thinking back a few years I went out to several engine breakdowns ( non starters ) whereby on an earlier Bosch course we were told that the latest diesel fuel sulphur content in LFO setups caused on certain types of inline pumps only rack bar seizures to occur with the rack bar in the stop position thus creating a non start situation.
The cure?
I was told that ice in a bucket poured over the pump especially in the top gallery area would release the rackbar from the stop position enabling a start up to occur particularly on a hot engine.
This I thought was a typical windup and that such a remark was laughable as in my entire career I had never heard such rubbish.
Sadly for me I was proved to be wrong.
Talk about live and learn exercise.
The added sulphur scenario was dropped from LFO and we never ever experienced it again.
I found it really weird and had it not happened to me almost unbelievable, you only experience this type of thing once in a lifetime and it goes to show you never know what's around the corner in this trade.
So perhaps adding just a small amount of HFO to LFO is not a good idea at all causing major gum up problems throught the system, particularly on the smaller stuff from the sightglass onwards.

[D Winsor]

Thinking back a few years I went out to several engine breakdowns ( non starters ) whereby on an earlier Bosch course we were told that the latest diesel fuel sulphur content in LFO setups caused on certain types of inline pumps only rack bar seizures to occur with the rack bar in the stop position thus creating a non start situation.

Caterpillar had a similar problem with the single rack bar that controls all the individual pumps in a self contained block assembly jamming in their "V" type engines such as the the 379, 398 & 399 series engines. However their problem wasn't so much with the lack of sulphur in the fuel, because Cat's have a very discerning palate when it come to the fuel they drink and they only like the best, rather because of the pump design without any kind of spring release on the pinions of the individual injection fuel pump plungers therefore if an individual fuel pump were to seize the rack would jam. A seized plunger besides prevent the engine from starting will more often cause the engine to overspeed with disastrous results. A jammed rack also prevents the mechanical or electronic overspeed safety shutdown systems from working so the engine will run away until it destroys itself if the engine cannot be stopped by some other means. In order to correct the problem without a complete redesign of the fuel pumps Caterpillar installed latched spring loaded dampers in the air intake manifolds. If the engine were to overspeed due a jammed fuel rack an engine driven speed switch or remote kill switch would activate the dampers trip coils causing the dampers to close starving the engine of air. Depending on the position of the rack the engine would sometimes continue to run, all be it very roughly, giving an opportunity to shut the fuel off and prevent parts being thrown the engine space.

[Merlyn]

Rod out the side jobby here methinks, scary stuff.
Going way back in time I used to have Diesel engines that ran on ether and castor oil.
High speed too.
I can smell it now even after all these years.
And it had a contra piston to adjust the compression ratio?

[JollyJack]

I used to think that Cats were the biggest heaps of shit ever designed to sell spare parts.......then I met Cummins

[Merlyn]

But they didn't run on ether and castor oil?

[D Winsor]

But they didn't run on ether and castor oil?

Cummins probably could because it had a common rail fuel system with adjustable mechanical injectors

[Big Pete]

Sounds more like the alternative to "Glow Plug" engines for model Boats etc. I had one about 50 years ago....

Big Pete.

[Merlyn]

Spot on BP, reminiscence of youth memories, wind the contra piston down with that T. Handle where it was tapped " very fine thread ) in the head to increase the compression ratio. Had a " contra piston" in the bore above the actuall piston.
And for the boats a miniature water cooled manifold.
Fond memories indeed.
Cut fingers for the planes caused by repeatedly swinging the propeller with your pinkies when you had a rotten starter engine.
.

[JK]

But they didn't run on ether and castor oil?

Cummins probably could because it had a common rail fuel system with adjustable mechanical injectors

I wonder if the old Detroit 92 series could. They just kept running no matter the abuse.

[Merlyn]

Quick quiz for those of you perhaps not going back to work till next week and need a little challenge .
As a point of interest got called out to a non starter CR engine on Xmas Eve morning, went down to Limpo mode and when shut down refused to restart.
FCR read it, only old codes stored, erased them cranked over, none reappeared.
Faced with several hours diagnostics oscilliscoping etc and Xmas looming on the horizon rapidly I decided to short circuit the usual diagnostic route and perform a quick test I learnt back in the mid eighties ( you didn't get this on any courses ) to instantly tell me whether it was fuel or the electrical side of things.
What did I do?

[JK]

Start it local?

On second thought, can you even start the new generation engines locally by bypassing all the remote starts?

[Merlyn]

When you say local do you mean short circuiting the LT side and bridging the starter/ cranking motor?
i.e. via the solenoid?
To perform this dodge / trick you can crank from the control panel or starter direct.
Apon attaining cranking RPM you can conduct this instantaneous procedure for an immediate answer, fuel or electrics.
No kit required.
So now you know where to look.