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Hybrid Vehicles Hybrid Vehicles - Archived Discussions Hybrid Diesels? 
395 messages, Last post on Aug 29, 2007 at 7:27 AM
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Replying to: goodcrd (Dec 03, 2006 9:15 am) Isn't this vehicle being introduced in Europe? If so then gas prices would have to go down to hit $5/gallon. Actually I've never understood why manufacturers are making hybrid versions of these already fuel efficient vehicles like the 40 mpg Opal. Take a 20 mpg vehicle and increase its fuel efficiency by this same 25% and you'll save twice as much money on fuel. When people talk about not recovering the hybrid premium they seem to rarely mention the resale value. If you get rid of your car after 3 years it will probably be worth about 50% of what you paid for it. So at that time you recover half of the hybrid premium. |
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http://www.evworld.com/view.cfm?section=communique&newsid=13635
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Replying to: marcb (Dec 08, 2006 11:18 am) I'd buy that car today if it were for sale in the USA. |
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Too bad this car never made it into production. Hybrid diesel 4-dr sedan, 108 MPG in the year 2000. GM Precept The hybrid-electric Precept is driven by a battery-powered electric traction system that moves the front wheels, and a lightweight, 1.3-liter, 3-cylinder diesel engine in the rear. The direct-injection engine, featuring turbocharged compression ignition, was developed by Isuzu Motor Co. Ltd., one of GM's Asian affiliates.
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Replying to: larsb (Jan 28, 2007 5:39 am)
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Replying to: kdhspyder (Jan 28, 2007 10:07 am)  Looks like Toyota now has that engine, and they already have had the hybrid side, so all they gotta do is put 1 and 1 together, and with their superior HSD technology over whatever GM had in the Precept......we might get 110-120 MPG in the diesel/electric hybrid they build. KDH, will you sell me one of these when they build it ??? 
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Replying to: larsb (Jan 28, 2007 11:57 am)  My Prius will be 5y.o. then and have about 200,000 miles so I'll be ready.
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... A thermodynamicist might say, the turbo takes heat and turns it into rotation, but let's look at what actually happens. Some of the efficiency is a reduction in pumping losses, but a big on-highway truck, at a fairly common 40 pounds of boost, is making fifty horsepower, just by turning the intake stroke into a power stroke, not even considering the increased cylinder filling. If you take the standard BMEP equation and go to the IMEP equation with, the 40 pounds pressure, with a nominal 850 cubes that is the horsepower created. ... This is a little harder to calculate, because I don't know the BSFC numbers from back then. The performance of todays vehicles is taken for granted but the level would take a non turbo engine of 1500 cubes. Back in the early Sixties turbos where almost as rare as they are ubiquitous today and most typical normally aspirated, 850 cube engines, made horsepower in the low two hundred level; today drivers expect 500 plus hp. |
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I will try and post a sane distillation of whats in my head! I know the major thing holding back all electric vehicles per se is battery technology, we can't get enough juice for the given size/weight to make an electric car go the distance we would want out of a family car (what about 350 miles on a tank) I also know that even the latest li-poly batteries still take a while to charge... I also know that if we all made a slight change in our driving habits and if our workplaces would provide sockets for charging your car whilst at work and our respective governments help put in place the infastructure for charging your car at home(I live in an appartment without a garage, so running an extension cord out to the car would get me loads of more headache  ) we could all live with and love the current best of breed electric cars (tesla roadster is an example of the right technology, but, the wrong application for most of us) That said I also think a better more gradual change involves, hybrid cars that still run on petrol, but, eek out the most efficiency out of the fossil fuel and as a by product lower emissions drastically. Which brings me to the meat of my post, Ive posted some of this here before, but talked about a diesel engine powering a generator that charges an onboard battery and drives an electric motor that drives the wheels (a serial hybrid). I realise that by adding the conversion from fossil fuel to electricity and storing most if it then converting it back to motive power to the wheels involves a few losses of efficiency. But really how much are we talking here? Im going to make some assumptions here: (these are not based in fact, just my guess) Typical motor electricity to motive power efficiency: 85-90% Typical generator motive to electricity efficiency: 80-90% So a simple scenario where we replace the drive train (gearbox, clutch, drive shafts) with a generator coupled directly to our gasonline engine, which then powers a motor driving the wheels, would net us a lower estimate of about 68% of the engine output (85% * 80%). With the original clutch/gearbox in place I know you lose some of the engine power too, what is this roughly, about 10-15%? Would this electric drivetrain be any lighter than the equivalent mechanical drive train(gearbox, clutch) I know drive shafts would be needed for the electric motor too, but with in wheel motors being talked about this too might not be needed! How much loss in efficiency in using this electric drive train are we a talking about over the mechanical drive train? My of the top of the head guess would put it about 20%. Now couldnt this be efficiency loss be made up in using a smaller lighter gasoline engine (3 cylinder, lean burn, 1-1.5 litre capacity) that has been tuned to run at a higher rpm with turbo charging if necassary? Wouldnt focusing on a smaller lighter more efficient gasoline engine that dont need to provide a wide power band, just a very small highly efficient band of power producing electricity to power the motor. (you could even include some ultracapicators that could soak up the excess electricity produced if the car is moving too slowly for amount of electrical power the gasoline engine/generator combo is producing and if you were to use regenarative braking, this could then be used to provide extra power to the motor when needed, or when restarting the gasoline engine if its been shutdown) Sorry that this post is long, but, Im fascinated by all of this, should have been an engineer instead of the desk bound computer programmer that I am !!!! Any ideas, criticism is welcome as is any kind soul that can point out any huge holes in my understanding or concept. Its all gone very quiet on this board of late!
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Replying to: toyolla2 (Nov 25, 2006 9:05 pm) *************** "engine and a hybrid transmission consisting of two 100 kW motors and a 600-volt, nickel metal hydride battery pack. The engine is coupled to an electronically variable transmission that provides an infinite range of gear ratios to drive the wheels." After some digging I found that Cummins engines in the 250-280Hp are the prime movers for the above. And a max service speed of 65mph was quoted. **************************** Elsewhere someone provided these links regarding the iconic London Transport double decker bus. tfl= transport for London http://www.autobloggreen.com/2007/03/17/first-hybrid-double-decker-bus-hits-the-- road-in-london/ http://www.tfl.gov.uk/tfl/press-centre/press-releases/press-releases-content.asp- ?prID=1082&source=RSS§ion=press The release didn't state the manufacturer of the 1.9L diesel engine that powers this vehicle. The vehicle itself was built by WrightBus Limited. No indication was given either whether this was in fact a government funded project along the lines suggested by those researchers, that government funding be awarded only for designs with a 90Kw power ceiling. In the light of what WrightBus have achieved it's hard to see why Allison would need 210Kw for their vehicle. But if I was running GM I would be asking questions. T2 |
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