The Electric Car
in [Design]
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From: Spehro Pefhany on 1 Aug 2007 09:27 On Wed, 01 Aug 2007 06:17:26 -0700, MooseFET <kensmith(a)rahul.net> wrote: >On Jul 31, 10:45 pm, Spehro Pefhany ><speffS...(a)interlogDOTyou.knowwhat> wrote: >> On Tue, 31 Jul 2007 21:29:24 -0700, the renowned John Larkin >> >> >> >> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> >On Tue, 31 Jul 2007 18:08:26 -0700, MooseFET <kensm...(a)rahul.net> >> >wrote: >> >> >>On Jul 31, 8:19 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >> >>Web-Site.com> wrote: >> >>> On Tue, 31 Jul 2007 08:14:21 -0700, John Larkin >> >> >>> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>> >On Tue, 31 Jul 2007 14:37:31 +0000, Guy Macon >> >>> ><http://www.guymacon.com/> wrote: >> >> >>> >>Jim Thompson wrote: >> >> >>> >>>I don't ever recall saying "more-efficient-at-higher-speed". >> >> >>> >>>But I guess it WOULD depend on your definition. The engine is >> >>> >>>optimized right around 3000RPM (85MPH), but external drag is higher. >> >> >>> >>Assuming that "optimized" means maximum efficiency as opposed >> >>> >>to maximum power or torque, wouldn't it be more efficient at >> >>> >>3000 RPM in first gear? >> >> >>> >>Part of me thinks about the far lower drag and says that it >> >>> >>would. Part of me thinks about those pistons moving up and >> >>> >>down more times per mile and sucking in about the same amount >> >>> >>of fuel per cycle and says that it wouldn't. Maybe it needs >> >>> >>an engine sized for 3000 RPM in first gear to make it work? >> >> >>> >>Also, I can't prove it, but I suspect that hard accelerating >> >>> >>to some speed (don't know how fast) and then shutting down >> >>> >>the engine and coasting down, then repeating, gives the >> >>> >>maximum fuel economy. >> >> >>> >Interesting curve: >> >> >>> >http://www.fueleconomy.gov/feg/driveHabits.shtml >> >> >>> >And it is reasonable to also factor in the value of your time. >> >> >>> >John >> >> >>> "Remove excess weight"... don't give a leftist weenie a ride ;-) >> >> >>At those speeds it is drag not weight that matters. You shouldn't >> >>wear a dress while driving. >> >> >You get the best mileage if you wear nothing at all. >> >> I suspect Spandex is better than nothing. More slippery than hairy >> surfaces and it could prevent the energy-sapping oscillation of fatty >> and/or dangly bits. >> >> >John >> >> Interesting that modern hybrids apparently get better gas milage in >> city driving rather than highway. >> >> Eg. Prius 60mpg city, 51mpg highway >> >> http://www.toyota.com/prius/specs.html > >This is as you would expect if they are making good use of the energy >in the fuel. Sure. It's interesting to see that they've actually achieved it, with significant mileage improvment to boot, in a practical production car. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
From: Ren� on 1 Aug 2007 09:27 On Wed, 01 Aug 2007 06:17:26 -0700, MooseFET <kensmith(a)rahul.net> wrote: >> Eg. Prius 60mpg city, 51mpg highway >> >> http://www.toyota.com/prius/specs.html > >This is as you would expect if they are making good use of the energy >in the fuel. Marketing figures...."Top Gear" (GB car TV show) registered a Prius not doing better than 45 miles / gallon. In Europe, popular diesel cars easily beat that with simple, non-hybrid engines. -- - Ren�
From: John Larkin on 1 Aug 2007 10:09 On Wed, 01 Aug 2007 08:57:00 -0400, Spehro Pefhany <speffSNIP(a)interlogDOTyou.knowwhat> wrote: >>People don't buy Prius' to save gas, they buy them to be hip and >>stylish. So instead of smog, we have clouds of smug. >> >>John > >Yes. _South Park_ dubbed it the "Toyota Pius". My calculations >indicate the payback to be marginal on hybrids, even with a $4K >government subsidy, so long as gas remains around $3US/US gallon, and >the Prius yields significantly better mileage than, say, the hybrid >Camry. Both hybrids would get far better mileage if the batteries, the electrics, and all the fancy controls were dumped. What's left would be a small, light, slippery, ugly car with a small engine. All you'd give up is acceleration and the questionable advantage of regenerative braking, a small price to pay for dumping the batteries. John
From: John Larkin on 1 Aug 2007 10:15 On Wed, 01 Aug 2007 06:22:36 -0700, MooseFET <kensmith(a)rahul.net> wrote: >On Jul 31, 9:12 pm, krw <k...(a)att.bizzzz> wrote: >> In article <1185930451.854228.138...(a)x35g2000prf.googlegroups.com>, >> kensm...(a)rahul.net says... >> >> >> >> > On Jul 31, 7:21 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >> > Web-Site.com> wrote: >> > > On Mon, 30 Jul 2007 20:02:28 -0700, Richard Henry >> >> > > <pomer...(a)hotmail.com> wrote: >> > > >On Jul 30, 7:20 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >> > > >Web-Site.com> wrote: >> > > >> On Mon, 30 Jul 2007 19:12:03 -0700, Richard Henry >> >> > > >> <pomer...(a)hotmail.com> wrote: >> > > >> >On Jul 30, 5:48 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >> > > >> >Web-Site.com> wrote: >> > > >> >> On Mon, 30 Jul 2007 17:30:01 -0700, "J.A. Legris" >> >> > > >> >> >- I said fuel consumption will never decrease much unless cars are >> > > >> >> >much lighter, but even radically lighter vehicles are no long-term >> > > >> >> >solution on this overpopulated planet >> >> > > >> >> Amen! I keep telling people that, and they look at me like I'm some >> > > >> >> kind of idiot. >> >> > > >> >You have also told us how you like to drive your big import illegally >> > > >> >fast and tried to rationalize it by claiming that among the vehicle's >> > > >> >luxury features is that it runs more efficiently at high speed. >> >> > > >> I didn't rationalize anything. However I do agree that leftist >> > > >> weenies should be taxed more heavily to support my excesses ;-) >> >> > > >> And I certainly have no problem with YOU driving a tin can, just NOT >> > > >> my children and grandchildren ;-) >> >> > > >OOHH!. Think of the children... >> >> > > >You sound like a leftist weenie. >> >> > > >Please explain again the more-efficient-at-higher-speed feature. >> >> > > I don't ever recall saying "more-efficient-at-higher-speed". >> >> > > But I guess it WOULD depend on your definition. The engine is >> > > optimized right around 3000RPM (85MPH), but external drag is higher. >> >> > If you shift to a lower gear, 3000 RPM is at a lower speed. If there >> > isn't an issue that is well modeled by a fuel leak, the milage would >> > improve. >> >> Ever consider that transmissions aren't equally efficient in all >> gears > >Yes but he didn't report he was driving with a faulty one. > >> and perhaps the over-drive locked-up may be a tad more >> efficient than the lower gears? > >A tad but not enough to make the difference. The energy per mile >increases as the square of the speed. Not in this graph: http://www.fueleconomy.gov/feg/driveHabits.shtml I've seen a few other mpg-vs-speed curves, and they all look similar. Looks like aerodynamic drag starts to seriously kick in above 55 MPH. John
From: Jim Thompson on 1 Aug 2007 10:16
On Wed, 1 Aug 2007 00:12:10 -0400, krw <krw(a)att.bizzzz> wrote: >In article <1185930451.854228.138310(a)x35g2000prf.googlegroups.com>, >kensmith(a)rahul.net says... >> On Jul 31, 7:21 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >> Web-Site.com> wrote: [snip] >> > >> > I don't ever recall saying "more-efficient-at-higher-speed". >> > >> > But I guess it WOULD depend on your definition. The engine is >> > optimized right around 3000RPM (85MPH), but external drag is higher. >> >> >> If you shift to a lower gear, 3000 RPM is at a lower speed. If there >> isn't an issue that is well modeled by a fuel leak, the milage would >> improve. > >Ever consider that transmissions aren't equally efficient in all >gears and perhaps the over-drive locked-up may be a tad more >efficient than the lower gears? There is also work done just >spinning the engine. Me thinks you're wrong. Don't both Honda and Toyota have models with CVT (continuously variable transmission) which keeps engine RPM's in a narrow/optimum range? ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave |