Talk:Brake-specific fuel consumption

message: I find having numbers smaller then 1 confusing if they aren't preceded by a zero.
i.e. .0123
I'd prefer 0.0123
Any thoughts?
--Stripy42 14:18, 17 April 2007 (UTC)
thread_title: Untitled

message: I think I've got the calculation right. Basically power is energy per unit time, but energy is force times distance. Distance is speed per second. Hence if you multiply the N produced by the speed, you get power. Once you have power you divide by 3600,000 to get kWh. Stuff like that.- (User) WolfKeeper (Talk) 05:48, 20 May 2008 (UTC)
thread_title:  Jet engine figures for GE-CF6 

message: Sorry, this does not belong in this article. Brake power refers to shaft power. Combined cycle systems use the heat output as part of their claimed useful output. Compound cycles and such like  are ok, as electric power is effectively shaft power. What do you think? Greg Locock (talk) 12:39, 20 May 2008 (UTC)
thread_title: combined cycle efficiency

message: Greglocock posted the Prius THS II figures in the table on engine BSFC. Even though the figures are interesting, I thought the inclusion of the Toyota used engine being the 1NZ-FXE engine which has a BSFC of 245g/(kW-h) by itself, should also be posted. The table posted is of engines only and not of engines and electric motors combined (hybrids). All other engines in the table would show higher efficiency used with hybrid type setups. A reference to the BSFC figure of the Toyota engine is: http://www.electrifyingtimes.com/priustechspecs.html
::The BSFC is for the engine alone. The reference for it is an SAE paper, for heaven's sake, not some blog. Greg Locock (talk) 07:11, 29 May 2008 (UTC)
replies: text: You reveal a disturbing lack of familiarity with the engineering literature. Greg Locock (talk) 07:11, 29 May 2008 (UTC)
thread_title: Posting of the Prius THS II BSFC figures

message: The prius does not produce it acclaimed efficiency of 236 g/(kW•h). The reference given is to do with compression ignition engines i.e. diesel engines, and has absolutely nothing to do with the prius. 
According to this site it is only capable of a maximum efficiency of 245 g/(kW•h). 
http://www.electrifyingtimes.com/priustechspecs.html  —Preceding unsigned comment added by Siripswich (talk • contribs) 21:06, 17 December 2008 (UTC)
replies: text: You've probably been misled by the mismatch between ref nos and footnote numbers the actual ref is to SAE paper SAE 2004-01-0064 . There was a difference between the first and second geenration prius motor. Greglocock (talk) 02:03, 18 December 2008 (UTC)
replies: text: Sorted, the sae paper says 225 Greglocock (talk) 02:22, 18 December 2008 (UTC)
thread_title:  Prius efficiency 

message: In a SI engine: why does a reduction of throttle losses increase the brake specific fuel consumption? One of the links in the headline probably offers the answer, but I am confused.
Arnero (talk) 14:39, 7 March 2009 (UTC)
replies: text: Does it? Greglocock (talk) 23:54, 7 March 2009 (UTC)
thread_title:  Article needs more links to [[lambda]], [[swirl]], [[Miller cycle]], [[turbo]] 

message: The first paragraph of this Wikipedia entry reads: "Brake specific fuel consumption (BSFC) is a measure of fuel efficiency within a shaft reciprocating engine. It is the rate of fuel consumption divided by the power produced. BSFC allows the fuel efficiency of different reciprocating engines to be directly compared."
I'm no engineer, but this makes no sense to me. If it were so, then let's say I put a teaspoon of fuel in my Bugatti Veyron and a teaspoon of fuel in my Prius. The Bugatti puts out 1000 hp for, say 10 seconds, while the Prius puts out, I dunno, say 50 hp for a few minutes. Yet if BSFC is in fact a measure of fuel per unit POWER, isn't the Bugatti getting a lower number, thus indicating it's more efficient? 
I don't understand this definition, although I see it other places. BSFC's units are kg/kWh, and kWh, unless I am completely high, is a measure of ENERGY, not power. So says Wikipedia; so says common sense. What am I missing?Pschwiesow (talk) 23:06, 4 March 2010 (UTC)
replies: text: You're almost/mostly right; but the article isn't wrong. BSFC is the RATE of fuel consumption divided by the power. Rate of fuel consumption is fuel consumption divided by time, and power is energy consumption divided by time. The time's cancel, which give you fuel consumption per energy which is what you say.- Wolfkeeper 23:46, 4 March 2010 (UTC)

text: They use rates though because a rate is an instantaneous thing, whereas fuel consumption and energy would have to be an average or total; but the BSFC is really the max, which is not an average, it's the peak.- Wolfkeeper 23:46, 4 March 2010 (UTC)
thread_title:  Why isn't it fuel consumption divided by ENERGY? 

message: The subject line expresses the idea.  — Preceding unsigned comment added by Mark.camp (talk • contribs) 23:57, 13 March 2014 (UTC)
thread_title:  Is it correct to say that BSFC does not apply to turbines and other non-reciprocating engines? 

message: Substituted at 10:11, 29 April 2016 (UTC)
thread_title: Assessment comment

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thread_title:  External links modified 

message: Sorry, I do not believe 200 g/kWh  for the Insight engine, and if it is correct then the % efficiency is wrong. if you don't understand why then you should not be editing the numbers in this article. Greglocock (talk) 01:19, 15 August 2017 (UTC)
replies: text: Ecomodder notes that the 200 figure was obtained with electric assist, without it was 215, still a very good figure. http://ecomodder.com/wiki/index.php/Brake_Specific_Fuel_Consumption_(BSFC)_Maps#1st_Gen_Honda_Insight_1.0L.  Greglocock (talk) 01:36, 15 August 2017 (UTC)
replies: text:  I did find the ref :  Testing methodology is inconsistent, as noted, with the whole car on a dyno (with the hybrid drivetrain), not the engine by itself : tests found 195g/kW/h for the prius, claimed for 225g/kW by Toyota. I removed the claim as unreliable.--Marc Lacoste (talk) 09:18, 15 August 2017 (UTC)

text:  even 215g/kW/h is dubious and no serious ref is given by Ecomodder--Marc Lacoste (talk) 09:22, 15 August 2017 (UTC)

text: Figure 4 in SAE 2009-24-0065 https://deepblue.lib.umich.edu/bitstream/handle/2027.42/89873/SAE%202009-24-0065.pdf;sequence=3 suggests that 230 is more like it. Greglocock (talk) 22:35, 15 August 2017 (UTC)
replies: text:  It looks like from a simulation (fig.2), but at least it's coherent with the 30g/kW/h difference of R. Trigui et al.--Marc Lacoste (talk) 17:16, 16 August 2017 (UTC)
thread_title:  Honda Insight unbelievable 

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message: There is no column for BSFC in SI-units. Even though there is a column for g/(kW*h), neither g, kW or h are SI-units. I think there ought to be one in kg/(W*s)...--Petkr (talk) 12:56, 12 April 2022 (UTC)
replies: text: g/KWh is usual in metric units. It gives the engineer an easy way to compute (even mentally) the total fuel consumption. kg/W/s figures would be smaller by 1000 * 3600=3.6M ! Illegible. MJ/kg would be the SI unit, and is often used for fuel energy content. I'm not sure there is a requirement in Wikipedia to use SI units, but to use widespread WP:units. --Marc Lacoste (talk) 13:18, 12 April 2022 (UTC)
thread_title: Units

message: ... but as I'm unfamiliar with the table code syntax, I would prefer not to break anything. Please add.
http://www.wwiiaircraftperformance.org/Aircraft_Engines_of_the_World_Packard_Merlin.pdf
Packard V-1650-1 V12: SFC: 205 g/hp/hr, 0.452 lb/hp/h, 275 g/kW/h 
http://www.wwiiaircraftperformance.org/p-47/P-47B_41-5902_PHQ-M-19-1417-A.pdf
Pratt & Whitney R2800-21 Radial: SFC: 0.78 lb/hp/hr
Mrdarrett (talk) 15:25, 19 October 2023 (UTC)
thread_title:  Requesting to add data for 2 engines