An all-electric car with 200 hp and 183 ft-lbs of torque, doing 0-60 in 3.6 seconds since all 183 ft-lbs of torque are available from 0 rpm... oh and a 110 lb 10k rpm engine...

*drool*

http://www.forbes.com/technology/200...l_1021vow.html

I do wonder the costs of charging an electric car vs paying for gasoline at the pump though... anyone know? This is where a hybrid would be really convenient... best of both worlds...

 

Looks pretty interesting but I hope they get alot cheaper.

I've got to disagree with the article in that I don't think the torque peaking at 0 has much, if anything, to do with its good accel numbers. Its the amount(peak) torque/horsepower compared to its low weight that makes it that fast.

 

It'd depend on how efficient their battery/power delivery system is, but let's try it anyway because I'm bored (I'll give them the benefit of the doubt and assume it's 100% efficient). Sorry to have to do this in metric units, but English units would make it even more confusing (for me at least):

So, the energy content of gas is 44,000 kJ/kg. Its density is something like 690 kg/m^3 = .69 kg/L. So that's:

(44,000 * .69) [kJ/kg * kg/L] = 30360 kJ/L

Air density is 1.2929 kg/m^3 = 0.00129 kg/L. I'll assume that the fuel volume is negligible compared to that of air (liquids are much more dense than gases). So, to fill up our 2.4 liter engine, we need:

(2.4 * 0.00129) [L * kg/L] = 0.0003096 kg of air/fuel mixture. (I know I should start using a scientific notation, but I think it'll confuse people)

If you're running at an equivalence ratio of 1 (neither rich, nor lean), then your air/fuel ratio (mass) is 14.6:1. So there's:

(0.0003096 / 14.6) [kg/1] = 0.0000212 kg

of fuel used to fill up 4 cylinders. Now, there's only 1 intake stroke per crank revolution (on a 4-cyl), so that last number should be divided by 4 because it represents 4 intake strokes worth of fuel. So that's 0.000005301 kg per revolution. Let's say we're running at 3000 RPM. We're using:

(0.000005301 * 3000) [kg/rev * rev/min] = 0.0159 kg of fuel per minute.

And I just realized that I should have left that in Liters :P....so that's:

(0.0159 / .69) [(kg/min) / (kg/L)] = 0.02305 [L/min]

I'm not sure what gas prices are per liter, so I'll convert to gallons real quick....

(0.02305 * 0.2642) [(L/min) * (gallon/L)] = 0.005675 gallon/min

I'll assume premium gas costs $2/gallon:

(0.005675 * 2) [(gallon/min) * ($/gallon)] = 0.0113 $/min.

WHEW! So it costs 1.13 cents per minute gas-wise (it's actually less, cars run lean most of the time) to operate your TSX. Let's try the electric thing.

The only way I can think of to do this is to take the electric car's power and convert to kilowatts.

(200 / 1.341) [HP / (HP/kW)] = 149.14 kW

I'm doing this because electricity is paid for in kW-hours. So let's put it at 3000 RPM just like the gas engine. Then power should be:

149.14 * 3000/5000 = 89.49 kW (the power curve should be exactly linear since the torque curve is exactly flat -- power becomes a function only of RPM).

I haven't looked at this in a long time, but I think electricity costs something like 3-4 cents per kW-hour (if people disagree, let me know and I'll change it). I'll use 3.5. Let's make it kW-min:

(0.035 * 1/60) [$/kW-h * h/min] = 0.000583 $/kW-min

Then we can take that and multiply by the power we're using with the electric motor:

(89.49 * 0.000583) [kW * $/kW-min] = 0.05217 $/min.

I hope I haven't bored you away! We're just getting to the fun part. Let's compare:
2.4L TSX ;; This electric car
1.13 cents/min ;; 5.22 cents/min

I told you I was bored! I admit that this calculation is VERY, VERY simplified and I've made a bunch of assumptions. But it's not more than an order of magnitude off. And even giving that to the electric straight out, which is a BIG gift (so it'd be 1.13 c/min vs. 0.522 c/min) it's still only half as cheap to run the electric car. My point (I think) is that gas is REALLY, REALLY cheap in the US. So it's hard to fight with it on an energy content basis.

I'd like to know what their calculation is for a "70mpg equivalent". "Zero emissions" is definitely false. I guess they think that the power in an electric socket is generated by the electricity fairy. Wrong. It's usually generated by that coal-burning power plant down the street. So there's still emissions as a result of driving this car. They've just been moved to a more central location. I hate it when people ignore this. It makes IC look bad...

OK. Discuss!

PS. Other engineers, feel free to flame me but please don't give me a hard time because of my significant figures. I never did understand that concept....

 

I have to applaud your attempt at comparing, and since I don't know anything about electricity, I'll assume you're right, until someone proves you wrong. But anyway, props on the detailed explanation.

 

I am software engineer, so this is the only thing I can give you ....

 

First of all, GOD DAMNIT Clutch, I'm not even going to attempt reading your post. So I'll just say this

:phatyo:

rzee, your still a whore

 

My systems analysis prof always taught me that the parts were user requirements!

 

Hey, I am an (software) engineer! so I am allowed to whore this thread. Stop being a , you !!!!

j/k

 

Something's wrong, at 60 mph your TSX will burn almost 2 gallons of gas in 1 hour, or roughly $4/60 minutes = 6.7 cents per minute.

What did I miss?

EDIT: Maybe that assumption of 100% efficiency, quite a leap for an internal combustion engine...

 

That assumption was for the batteries in the electric... but you're right (I think). Hold on....

Edit: No, that should be a good number. Here's what you missed: I'm not looking at the work output at all, so efficiency (work out/heating value of gas) doesn't come into play. I'm just talking about running the engine at a given speed, so all I have to calculate is fuel consumption (what the original question was about) regardless of what work/power I get out of it.

Edit again: When you're travelling on the highway, then the work/power output you get is important. And to get the required amount of power, you have to overcome all the inefficiencies. So, some extra fuel is wasted overcoming: combustion inefficiency, mechanical (friction) inefficiency, heat losses, exhaust blowdown losses, transmission losses, rolling resistance (deformation of the tires), air resistance, etc., etc. Most of the same would apply to the electric as well (obviously not combustion and exhaust inefficiency). This was a true back-of-the-envelope calculation, and doing all that stuff would take a long time. I just did this on my break between classes. Anyway, I think this is the difference we're seeing (because your 2 gal/hour at 60mph is correct). And actually, that sounds about right b/c the overall efficiency of a gas engine running at 60 is ~25%. And (forgive me)

6.7 [cents] * .25 = 1.675 ~ 1.13.

Anyway, all I was trying to point out is that an electric car is not THAT much cheaper than a gas engine. If you're still not happy, give the electric that factor of 10 that I offered it. It's still only a little less than half as cheap to run.

 

Nice!

That's what I feel like everytime I have to program in C....

 

Rzee, that was TOO funny!!

Post of the month!

 

OK you guys, let's not confuse electric cars with hybrids. Electric cars have to lug around a trunkful of big, heavy batteries. The latest hybrids get their electricity from regenerative braking, and the juice is stored in a much smaller set of batteries than an electric car's. The upshot is, hybrids are lighter than electrics, and much more efficient than gasoline-powered cars, and don't need to be plugged in at night.

http://www.hondacars.com/models/engi...e=Civic+Hybrid

 

Fair enough, but this analysis is based on today's supplies.

We will run out of oil (just a matter of time, in fact some claim that world oil production potential is already near peak and will decline soon -- note the word potential before you jump on this), while there are prospects for almost unlimited electrical power at some point in the not too distant future if we can manage to harness fusion, etc.

 

IMA works. I save so much money per week it's not even funny. I would normally commute in with my Integra GSR (which requires 91 (I use 93 because that's what we have here)) octane but now I commute in with the Civic Hybrid which uses 87 octane gas (so i save a few bucks there on just octane level). Here is the kicker, my fiance who drives our Hybrid works down the street from me so we can commute in together. So instead of paying for gas on both cars, we just buy for one. I now fill up my GSR once every 2 month or so. While getting 50 mpg with the hybrid.

 

Most definitely. In fact, I'm betting that our petroleum reserves will be gone in my lifetime (I'm 23). Fusion will be really cool (and from what I've read, we're pretty close), but I still say there is no substitute for internal combustion in a personal vehicle. I don't really care if it's ten times cheaper to run an electric vehicle, I just don't want to drive one. Did you ever ride in a power wheels car as a kid? That's what it's like.

So, yes we will run out of oil to burn, but there's LOTS of other things we can burn. So the obvious solution (to me anyway) is to burn something else! Like ethanol (which can be made from corn). Or if we get on this "Hydrogen Economy" (yeah right), you BURN THE FREAKIN' HYDROGEN instead of pumping it into a fuel cell (electric) vehicle.

Combusto Vivat Semper!