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Car Forum / Honda Cars / April 2008Plot of Engine Speed vs. Fuel Consumption
I am looking for a plot of engine speed vs. fuel consumption. Is one available anywhere? I am not at all picky about what specific engine. ecarecar4/12/08 16:49xpWdneNoe-6jvZzVnZ2dnUVZ_uLinZ2d@centurytel.net > I am looking for a plot of engine speed vs. fuel consumption. Is one > available anywhere? I am not at all picky about what specific engine. While each vehicle reaches its optimal fuel economy at a different speed (or range of speeds), gas mileage usually decreases rapidly at speeds above 60 mph. As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.20 per gallon for gas. Quote from the feds. Graph here: http://www.fueleconomy.gov/feg/driveHabits.shtml  SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply 1998 Civic HX MT with 142K 2000 CRV EX MT with 98K I have seen that graph. From where did the data come? >ecarecar4/12/08 16:49xpWdneNoe-6jvZzVnZ2dnUVZ_uLinZ2d@centurytel.net > [quoted text clipped - 14 lines] >http://www.fueleconomy.gov/feg/driveHabits.shtml > ecarecar4/12/08 21:54qM6dnePDJJxO-pzVnZ2dnUVZ_o3inZ2d@centurytel.net > I have seen that graph. From where did the data come? > [quoted text clipped - 16 lines] >> http://www.fueleconomy.gov/feg/driveHabits.shtml >> The URL says it all. The suffix .gov means it was published by a government agency. In this case it means the US Dept. of Energy with cooperation of the Dept of Energy Efficiency and Renewable Energy AND the EPA. SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply 1998 Civic HX MT with 142K 2000 CRV EX MT with 98K Such a graph must be stupid, of course consumption rises with rpm | gas mileage usually decreases rapidly at speeds above 60 mph. Not necessarily fr 60 mph, big factors incl [i] exhaust*manifold : cheapo 4-1 short branch * can give ¾ of maximum torque @ low rpm <1000, but gives <½ of maximum torque @>3000 rpm, & even less @ higher rpm [ii] voltage & ampere from small single coil ( esp if hot ) drop fast @>3000 rpm : sparks will be too small to ignite enough fuel before pistons reach b-d-c, esp where only cheapo carbon core cables are used [iii] cheapo mineral oil's coarseness are apparent only @ high rpm when only the most slippery oil ( e.g. synthetic with fullerene ) can produce high torque. [iv] gear ratios & axle (tyre) height >Such a graph must be stupid, of course consumption rises >with rpm [quoted text clipped - 13 lines] > fullerene ) can produce high torque. >[iv] gear ratios & axle (tyre) height Needless to say, this guy is wacko. By far the biggest factor in poor fuel economy at high speeds is wind resistance. Many vehicles (e.g. big SUVs) run less than 3000 rpm at speeds above 60 mph and get much reduced fuel economy due to their barn door aerodynamics. Of the above, only iv. will have any noticeable effect on fuel economy. To the extent that i. reduces power at high speeds it may actually reduce fuel consumption. Just throwing in some other good discussions for the archives: Optimal speed by model (compact, mid-size, van, etc.) http://auto.howstuffworks.com/framed.htm?parent=question477.htm&url=http://tqjun ior.thinkquest.org/4116/Trip_Planning/speed.htm Discussion of how resistance (especially wind resistance) causes fuel mileage to plummet at high (55+ mph) speeds: http://auto.howstuffworks.com/question477.htm >I am looking for a plot of engine speed vs. fuel >consumption. Is one > available anywhere? I am not at all picky about what > specific engine. Is there something not-too-expensive I could plug in to get the data for myself? > I am looking for a plot of engine speed vs. fuel consumption. Is one > available anywhere? I am not at all picky about what specific engine. > Is there something not-too-expensive I could plug in to get the data for > myself? > >> I am looking for a plot of engine speed vs. fuel consumption. Is one >> available anywhere? I am not at all picky about what specific engine. c'mon dude - you need to be much more precise with your questions to get meaningful answers. 1. do you mean engine speed or vehicle speed? 2. what kind of engine? 3. what kind of fuel? there's more, and it's a long list of highly significant variables. as for plug-ins, yes, you can use obd output data to compute consumption, if you know some other data, but it's a non-trivial exercise, and without knowing a /lot/ more detail, you're pretty much stuck with getting gas station receipt data, recording mileage between each fill-up, then driving different speeds. > I am looking for a plot of engine speed vs. fuel consumption. Is one > available anywhere? I am not at all picky about what specific engine. I suspect Universities that compete in building very fuel efficient vehicles (esp. hybrids) would have this information available to the public. Marine applications may be a source, too. Maybe Briggs & Stratton has that info. for their lawn mower engines. > > [quoted text clipped - 7 lines] > > You would think, but, actually, no. They may have it, but it isn't public. After years - literally YEARS - of searching, I found information that served my purposes. This will get you from 0 km/hr to 60 km/hr http://www.jari.jp/pdf/rt2005/09Fu_eng.pdf This will get you from 50 km/hr to 140 km/hr http://www.greencarcongress.com/2006/05/fuel_consumptio.htm The first, as you might have guess, is from Japan. The second is from Germany. <...> > After years - literally YEARS - of searching, I found information that > served my purposes. [quoted text clipped - 7 lines] > The first, as you might have guess, is from Japan. The second is from > Germany. This second link doesn't work for me. Even after correcting obvious spelling errors. Could you try again? Thanks. SignatureGraham W. www.gcw.org.uk Homebuilt Computer cooling. DIY projects Wimborne. www.wessex-astro.org.uk Society website, meetings, Dorset UK. location maps and future programs. "www.greencarcongress.com/2006/05/fuel_consumptio.html" > <...> > [quoted text clipped - 13 lines] > spelling errors. Could you try again? > Thanks. > "www.greencarcongress.com/2006/05/fuel_consumptio.html" > [quoted text clipped - 15 lines] >> spelling errors. Could you try again? >> Thanks. That works!! And so does the other one now if I edit an 'L' where needed. It didn't work before. Thanks again. SignatureGraham W. www.gcw.org.uk Homebuilt Computer cooling. DIY projects Wimborne. www.wessex-astro.org.uk Society website, meetings, Dorset UK. location maps and future programs. >> I am looking for a plot of engine speed vs. fuel consumption. Is one >> available anywhere? I am not at all picky about what specific engine. [quoted text clipped - 6 lines] > >Maybe Briggs & Stratton has that info. for their lawn mower engines. Here is a plot of Brake Specific Fuel Consumption vs. rpm for a VW TDI engine. http://forums.tdiclub.com/showthread.php?t=208125 BSFC is the measure of how much fuel is being consumed per unit power generated - a true fuel efficiency measurement. To get an absolute fuel consumption rate, you could multiply the BSFC by power at a given rpm. Of course this all assumes wide open throttle. If you are running at a lower power setting, the absolute fuel consumption will be lower. I would guess that BSFC might be higher or lower depending on the way the engine is set up. Maybe the OP could tell us exactly what he wants to know. > > [quoted text clipped - 30 lines] > > This is WOT? Therefore, it is also full throttle ignition advance? The bottom of the curve is quite narrow. >> >> [quoted text clipped - 33 lines] >This is WOT? Therefore, it is also full throttle ignition advance? >The bottom of the curve is quite narrow. Well actually it is a diesel so there is no throttle (my bad) and no ignition. What I should have said is that I assume this curve is for maximum power setting. Again, it is not clear exactly what you are trying to show/learn here. For example, are you interested in fuel consumption at various engine speeds or car speeds? > > [quoted text clipped - 54 lines] > > I don't know which chart you mean. Not all the cars in the top chart at www.greencarcongress.com/2006/05/fuel_consumptio.html are diesel. >> >> [quoted text clipped - 60 lines] > >are diesel. I was talking about the chart I linked to above: http://forums.tdiclub.com/showthread.php?t=208125 (You have to page down a couple times to see it.) > I am looking for a plot of engine speed vs. fuel consumption. Is one > available anywhere? I am not at all picky about what specific engine. By laws of aerodynamics, air drag is proportionate to the square of the object's velocity. If the speed is doubled, then it requires a quadrupled energy to overcome the drag. At the same time, the object travels twice the distance. Spending four times the amount of energy to propel the object twice the distance means the energy efficiency is cut in half. Likewise, if the object's velocity is trippled then energy efficiency is reduced to one third.. and so on... In automobile, rolling friction is also a factor but it's a linear drag, while air drag is a quadratic drag. The combined result is closer to the air drag only model. In layman terms, if you've got a car that does 30 mpg at 60 mph, then you can expect 15 mpg at 120 mph. It can be more or less, depending on the efficiency of the engine's combustion chambers, and its own internal friction at higher rpm > > [quoted text clipped - 10 lines] > > Actually, it is a quadrupling of the force. >Likewise, if the object's velocity is trippled then energy efficiency >is reduced to one third.. and so on... [quoted text clipped - 9 lines] > > |
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