Elio + hub motors + diesel engine = 300mpg?

[swbluto]

I've been cranking out the mpg numbers for a generator powered electric geo metro (Since I noticed it had a princely effective drag area number of 6.08 ft^2 on wikipedia), and my estimations came out to about 30 mpg. Considering the original car gets about 42mpg, that idea didn't look too promising, lol.

However, I did run the numbers for a diesel generator and got something like 70mpg. Woah!

Diesel seems to be where it's at for fuel efficiency! (Diesel gets 20% more energy per gallon, and diesel engines seem to be something like 70-100% more efficient than gasoline engines for some reason. Possibly direct injection technology?)

So, realizing that simply running an electric car on a gas generator didn't exactly improve fuel efficiency, I thought that I'd actually have to redesign the car in order to improve fuel efficiency.

Well, there's the new 84mpg Elio coming out. Looks like it has half the frontal area and a pretty slick drag coefficient from the looks of it, so it seems like the perfect vehicle to use as a starting point. I figure if I used a high efficiency hub motor (90+% efficiency), and then ran a 30% efficient diesel generator that powered the motor (I'd probably build the generator myself since the cheapest 5000w diesel generators I could find cost about $1500 more than than the cost of a namebrand ~6000watt/7.5hp diesel motor, lol), I could probably get somewhere between 200-300 mpg at speeds of 55mph since the wh/mi would be around 50wh/mi. (One could drive faster if desired, but one would get noticeably decreased fuel economy since energy expenditure, and thus fuel consumption, is roughly square to velocity.)

So, what do you guys think? Got any ways to improve the mpgs? I'm trying to squeeze the best possible MPGs I can out of a highway vehicle because the idea of going on a cross-country roadtrip on $150 of gas sounds incredibly appealing. Or, if one were to primarily use batteries, which wouldn't cost /that/ much (Relatively speaking), one could do it on (10000mi*50wh/mi=500kwh*($.1/kwh)=$50) $50 of electricity. With the gas bill as of today being somewhere north of $1000 for such a trip, and how staycations are reaching an all-time high, lol, I'd say there's room for such a vehicle.

Here's the elio car:

 

[Dauntless]

I assume since the diesel doesn't burn as hot there isn't as much fuel evaporation for cooling, therefore greater efficiency. Another biggie experimented with is water mixed in alcohol, which does the evaporating and carrying out heat while the alcohol does the burning.

CrazyJerry has suffered near stardom with his diesel. http://endless-sphere.com/forums/viewtopic.php?f=34&t=59217

 

[Ykick]

Diesel fuel is more energy dense.

Diesel engines also more efficient since it operates using varying air/fuel mixture. Gasoline engines are pretty much stuck with stoichiometric air fuel ratio of 14.7 parts air to 1 part fuel over the entire RPM load range. Diesel engine can use AFR as high as 100:1 at idle and vary greatly since there's no throttle butterfly. The compression ratio is very high but the fuel injector system and upper end is constantly lubricated with fresh fuel oil. The engines can last for longer service life than gasoline.

 

[arkmundi]

I committed some time ago to the idea. Partly because I'm a member of Coop Power, which has a majority share in Northeast Biodiesel, which will go into production mode this year (yea!) I've already shelled out $2K for a 5KW generator. I'm going with the double duty concept, of power both for a home off-grid system and motive power. When time & cash allow, I'll get a used VW Beetle, tear out the motor, do a full electric convert and stash the generator in one or the other compartments. The car will power my home someday, maybe. Solar PV/Wind/Biodiesel.

 

[riba2233]

As far as I know, diesel is more efficient because it burns hotter than the gasoline Dauntless. But it has a my eff of about 35%, while gasoline has about 25%.

If you want to further increase your efficiency, maybe full electric? 8)

 

[Ykick]

btw, anybody thinking about using those single cylinder Diesel generators, good luck with that! My dad had one for about 2 minutes - OMG the vibration is/was something from a disaster movie, LOL.... It was downright comical. I dunno where you could mount one of those things and have it not shake anything/everything to pieces? Maybe in a field on soft turf?

Anybody hip to "rolling coal"? Google it, crazy cracker shit....

[youtube]cbAhfThNoco[/youtube]

 

[Punx0r]

Diesel engines are somewhat more efficient than petrol, due to the higher compression ratio, reduction in pumping losses due to the elimination of a throttle and, I believe, reduced engine speed, resulting it lower frictional losses. Most of the disparity in MPG is due to the fact diesel contains more energy and is more dense, so when measuring by volume you get more of it!

Miles-per-kg would reduce the disparity and miles-per-KWh would reduce it further, down to something like 10-20% difference IIRC.

Also, diesel generators are optimised for fuel efficiency. Petrol ones are generally designed to be cheap and light.

 

[Dauntless]

So whenever I read a comparison of the combustion temperature of diesel and gasoline, it's always something like 590c for the diesel and 710c for gasoline. I've never heard of diesel burning hotter. I've heard many explanations of problems based on gasoline burning hotter, such as why gas and diesel mixed destroys a diesel engine but not a gas engine.

Dang, all that info on the kubota D750 engine, the list of various sizes of used ones for sale, etc., all gone because the window vanished instead of posting. Don't really want to look it up again, I was just leaving the house. . . .

But the engines used for the 100mpg cars are the engines from tractors, tillers, boats, not little generator engines.

I'd say for converting, you want a newer car that will still have such parts as brake calipers, electrical modules, etc. available, not something 25-30 years old. Chevy Aveo might start at $1,500 and the engine and AC have resale value. Go bigger than the 17hp engine that struggles to get the 1,200 pound builds to freeway speeds when you convert a car that'll be over 2,000 pounds, even if the mpg has to drop some.

Or you build something that might weigh 700 pounds when you're done and put the 13hp engine in there, maybe top 150mpg. http://www.rqriley.com/u-car.html

Oops, they're waiting for me.

 

[Punx0r]

Accidentally post!

 

[The fingers]

Synthetic crankcase oil and ultra low-sulpher diesel fuel have helped make today's "clean" cars popular. Less stink, less smoke, less noise, fast, and better fuel economy.

 

[John in CR]

I say gut the Elio to dump the ICE and make it pure electric. That's the route to true efficiency, because electric motors are so much more efficient. Aerodynamic gains apply to both, though with so much less heat to reject an electric can more easily be made slippery through the air. Fuel is roughly the same price per unit of energy. Though once your vehicle body has significant surface area, you can't discount the amount of free fuel you can get from the sun, especially with solar panels now so cheap. Maybe you'd be lucky to pick up 1kwh in a day while in motion, but the simple combination of a long lunch stop with fold out solar panels angled to directly face the sun can drastically increase that. If a plug is convenient and cheap or free, go ahead and connect the modest power on board charger even at the same time you're catching some sun. The combination can significantly increase daily range and/or decrease required pack size.

Regarding the vehicle, if your goal is ultimate efficiency, then there's no argument that the teardrop is the most aero shape. That pushes us toward 2 wheels up front, but I take issue with the wheel width required up front unless it's a leaner, and I don't think the issues of leaning the wheels that steer have been completely solved. Wheels out wide like the Elio has to be a big hit to aerodynamics. OTOH a leaning delta is simple, and I'm confident that the very narrow track possible could make it ultimately more aerodynamic than the widely spaced front of tadpoles like the Elio. I have to believe that rounded motorcycle type tires will have less rolling resistance too. Deltas have less traction in front, and if that wheel breaks loose it's trouble. To help offset the risk of losing steering if the front wheel loses traction, I'd include a hubmotor up front as one of the drive motors. I wouldn't run it at high power, so no extra motor cooling is required, just enough to assist with positive torque up front and still be able to pull the front around for some steering control in all conditions. Using a motor to pull the front around instead of just pushing from the rear is simply better.

Going with a 2 wheeler plus landing gear like the Monotracer is a viable option to really take aero to the limits, but I'll stick with the simplicity of a leaning delta instead.

 

[Russell]

I tell ya if they actually can sell the Elio for $6800 we will be seeing a lot of them on the roads. Heck that's the down payment I made on my present car. That's a thousand bucks less than a Stealth Fighter E-bike (that's the cheaper Stealth E-bike). People will buy them for second cars, for kids cars and yeah for modifying.



-R

 

[Dauntless]

The way you build up a high mpg diesel at home is to discover that one of these used engines is powerful enough to do the job.

http://orangecounty.craigslist.org/boa/4678779855.html