diesel engine versus heavy fuel engine


Thread Starter


We have an application to run a diesel engine with heavy fuel oil. I would like to know if the engine KW will increase or decrease and how much. Any data will help. Thanks.
In general, you will derive more energy from the heavy diesel fuel because there is a higher carbon to hydrogen ration. You should be aware that with the heavier diesel that more particulate matter (smoke) will probably be emitted. This is an indication that the engine itself is reaching design limits

I would STRONGLY advise that the fuel specifications of the heavier proposed fuel be reviewed with the existing engine specifications (you can get engine specs off the web for most major manufacturers like detroit or cummins). In general, industrial diesel engines have specifications that should be followed if you have any engine warranty issues.

if you are going to evaluate the possibility of using this diesel, i would again advise that the heads and cylinders should be opened (or boroscoped) for inspection (with pictures) and reinspected after some preset period of operation.

in addition, if you have a computer controlled engine (like a detroit series 60) you might want to review the operating parameters in the computer and set up the computer to best handle the fuel that is going to be used. (i have found that the computer can have profound impact on engines operating outside the original pre-loaded computer parameters.

good luck

t mccully
[email protected]
In addition to what Mr.T Mccully has said check the cetane no. of the heavy fuel oil. If it is not close to that of the normal diesel oil then heavy knocking could take place, also the injection timing, & fuel quantity needs to be remetered.

Also whether the engine is turbocharged (supercharged) or naturally aspirated would also make a difference for its suitability for the heavy oil.

Tomy Zacharia

Dear Mr Johan,

In addition to the fine comments by the other participants, heavy fuels may have problems with high sulfur content. If this so, then to both prevent cold corrosion of injector nozzles and carbonization (fluting) of nozzles an injector temp control system is required. This maintains the injectors in a narrow band of temperatures.

Moreover residual fuel/heavy fuel will require to be preheated and or centrifuged to clear it of foreign matter. You will also face high exhaust temperatures with heavy/residual fuel. To protect the engine some measures such as water cooled exhaust seats and exhaust valve rotators are also employed. On larger engines piston rotators are also employed.

Heavy fuel will also increase your maintenance cycles. You might need higher alkalinity lube oil (higher TBN), frequent cleaning/overhaul of turbochargers, frequent cleaning of lube oil centrifuges etc.

The bottom line is talk to the engine manufacturer if possible, or employ somebody who has past experience of maintaining diesel engines running on heavy fuel.


Tomy Zacharia