Lowest feasible specific fuel consumption

[nuttydan]

Hey all. I am new to these fourms, but they look like a great resource.

For a diesel engine in the 15kw range what is the lowest specific fuel consumption one could expect (wide open) if a broad power band was not important? Would tuning an engine to run wide open at a constant load improve SFC?

Thanks in advance!

 

[SMOKEY44211]

I think the engine size selection would be more benificial then any tuning technique. Choose an engine that has a max torque rating that is up to the task. I believe a NON turbo diesel(4cycle engine) will out perform a turbo equiped one if the criteria is fuel in work out scenario. Expect #'s in the .32-.35 lbs./HP/HR. range. I also think that a two stroke diesel would have an advantage in terms of BSFC#'s but availability and cost probably would tip the scale in favor of 4 stroke.---------Phil

 

[sbmar]

Smokey,

I'd like to express a concern with your post as to BSFC, non-turbo, and maybe a 2-stroke............I do not dwell on what might be, but do have a good understanding of what is in the marketplace currently.. Your thoughts seem quite different to what is actually at the cutting edge of diesels today that are in the field working in their intended applications.

That be, diesels in both on-highway and off-highway applications that meet the latest EURO 3 and EPA Tier 2 and Tier 3 emission standards, and are typically 100% full authority electronics with late generation CR fuel systems burning #2 or light diesel... Maybe your answer was based on a hypothetical diesel, but nothing I have seen or read about in less than 3 liters per cylinder displacement, medium to high speed diesels would lead me to accept your answer.

We use .355 lbs/per hp / per hour as a magic number as this is approx. 20 hp/gal/hr based on #2 at 7.01 lbs per gallon. Seems to be close to an industry standard.. Yes, we do see as low as .31 or lower at peak torque, but never anything below .37 or so w/ a non-turbo engine, let alone any two stroke except in some very large units--- Slow speed diesels, large cross heads design, in the 500 to 1800 liter per cylinder displacement. BIG STUFF that is in a class of its own using heavy fuel...

Either way, this is not to argue, but to learn something that I may not be privy too.. I’m all ears...If I were to answer this question, I’d use your numbers, but leave out non-turbo and 2-stroke.................................................

Tony


Tony Athens

http://www.sbmar.com

 

[SMOKEY44211]

Hello Tony: Your post gave me cause to reconsider my recomendations to nuttydan. The way the question was worded (constant load)and subsequent enquiring of possible gain via tuning techniques suggest to me (perhaps erroneously)that the inteded application was for some sort of stationary equipement. Generator or pump come to mind. My shop repairs/rebuilds a number of what I would consider low power diesels in the power range mentioned in the question. Kabuta (water cooled) and Duetz (air cooled) are the ones that I see the most of. Last I knew these engines are still available new. Must admit these are not considered cutting edge units by anyones standards. No turbo, mechanical injection and lacking sophistcated electronics. They do however perform with the fuel consumption #'s I posted. Diahatsu makes a 2 stroke diesel that has impressive #'s. I think current engineering for engines in this power range has to be able to address the emission issue, as you pointed out, but from what I have read fuel economy generally suffers. Personally I think HCCI would be perfect for applications such as this (constant load and speed) but I am not aware of any manufactured offerings.------Phil p.s. I took a look at your website interesting and imformative.

 

[amorrison]

See

http://en.wikipedia.org/wiki/Specific_fuel_consumption