The Easy Leg: Vehicle Efficiency

[dcb]

Originally Posted by mcrews

...corvette

what is intesting is both of these cars were as light as possible and were FAST.
Key words: Light and fast. as a byproduct, the also got good mpg.
...

Lets try to get our terminology straight, 1985 mpg specs for a corvette is combined 17mpg, THAT IS NOT GOOD MPG!!!!

I mean if you were moving 2 tons of cargo over asphalt or 50 people it might be good, but were talking two people and maybe a handbag

[natefish]

Originally Posted by mcrews

But my point is that the 85 engines were not optimally effecient. That is the problem with the whole article.
85 was not some magical moment in mpg nervana.

I don't think the point is to go back to those engines per se, I think the point is to use modern engines, in modern cars, but reduce the HP so that it would be roughly the same HP/weight ratio of the 1985 cars...or even just reduce HP back a bit.

[bgd73]

the 1985 number is carburators. it is a fantastically twisted fairy tale about injection.

I lived through it. My carbed 90hp subaru is somebody elses 180 today..injections sucking in more fuel than ever...and funny enough within 200 pounds in real weight. it is grotesque to think how stupid they got with real automobiles. they even lie and lie and lie...
The heads up for me was having a 300hp v8 in the 10s at a quarter.. all of a sudden, the numbers in hp started increasing..and not doing a damn bit of difference. Wo. somebody is going mobster about fuel injection...it happened in the early 1990s.

The only place I saw hold true about power increases and staying the same fuel mileage is my dads rigs.. from 290- 550+..all 5-7 mpg...and of course, that is showing its true colors with the new v8 diesels by ford and gm.

cars are a hacked retarded midget wizard of oz fantasy in comparison.

[dcb]

I've been through it too, and maybe I misunderstand the fuel injection comments, but I only see benefits to electronic fuel injection in comparison to carbs.

They tried to give the carburetor feedback about how far off the mark it was, and tried to work around newly created problems with gobs of vacuum lines, but it was still guesswork and clunky.

Enter fuel injection. Suddenly it is easy to troubleshoot, just check for a signal, and if that looks right pop out the injector and point it in a glass and see what it does and how much it squirts. No flowbench or mojo required. No fudging with accelerator pumps or automatic chokes or other hacks of endearment.

Suddenly the cars are meeting emission requirements that were not practical with a carb that now resembled a potato trying to have kids. No eyes watering as you wade through huge numbers of unburnt hydrocarbons. Heck, even an occasional clear day in LA.

Now having refined the fuel delivery algorithms, direct injection is commonplace, and the throttle losses for gasoline even does not look necessary for much longer.

Mixture monitoring and control is one of the things computers are pretty good at. Yah, it gets abused by the cry and push for more power, but like most problems, that is a human phenomenon.

What am I missing bgd? have I misinterpreted your position or do you detest fuel injection on (current) technical grounds?

[autoteach]

I agree about keeping safety equipment, what I was saying was that we could not reduce the vehicle weight to early 80's weight for our subcompact market. those vehicles were seriously light (thinking japanese here).

Here is my thoughts on FI, it IS the only way for fuel efficiency. Forget the weight that it bears, HCCI engines will give you FE like you never have seen before. Just get that into a 1L or 1.5L engine and on a compact car, manual (no automanual, too heavy). For every pound you drop off the car in components, you drop weight in components. What I mean about that is lighter wheels need lighter springs, lighter car needs lighter springs. Lighter car and springs=lighter torsion bars, mounts, ball joints. Lighter seats, lighter suspension. Lighter bodywork, lighter carpet, electronics, cooling system (4 reduce engine size), reduce reduce reduce reduce

If the pattern is reduction, it is a self fulfilling prophecy. Go figure.

[mcrews]

Unfortunately, as I tried to make clear earlier, you cant "just drop this or that" wala!!!

The companies have a dollar amount that has to pay the cost to produce a unit(not manufactureing costs). let's say it's $5000 a unit. That covers the rent, the insurance, the electricity, the marketing, pension plans, etc. There are no actual car parts in that $$$.
Then they have to create a car. If we build a very light and simple car that cost 7,000 in material, then we have to mark that up so the manufacturer makes money add 1000.
Now it needs a sticker price so the dealer can make money add 2000. That is a 15,000 car. I can promis you that you would not buy this car. It would be noisy, uncomfortable, lack any real response......
THe A2 is listed at 22,000. Audi is probably not making any money at the price. That is
true for most car makers. THe low end of their model lines barely breakeven.

It is not like the manufactures DONT want to build the ideal car. But there is more than 1/2 the price that is sitting on the design table to start with.

I mentioned my 2002 Infiniti Q45. It has an aluninuum body, suspesion parts etc. At $60,000 Infiniti never made any money on the Q45 brand.

I don't mean to belabor the point, but it's not that the ideas arent there. THe business model is very broken.

[jamesqf]

Originally Posted by mcrews

THe low end of their model lines barely breakeven.

But there's the problem: equating "light and simple" with the low end of the product line. Consider the opposite approach, in which Lotus builds the light and simple Elise and sells it at $48K.

Or to take the CRX as a base, Honda sells the Fit at $15-20K MSRP. Suppose they started with the basic Fit platform, and built the lighter, quicker next-gen CRX on it. Wouldn't there be people willing to pay a $5-10K premium over the basic Fit for one?

[comptiger5000]

To get good MPG, you don't have to cut HP. However, you have to have a well-designed, efficient engine that scales to load well.

If we take generators as an example, we can see the advantage of diesel over gas in a huge way. For example, we have generator A (gas), and generator B (diesel), which are both capable of producing the same power, both turn a constant 1800 RPM, and both use 2 gallons per hour at full load.

However, we see the difference in the part load consumption, where something resembling this occurs:

Generator A

No load - 0.6 gph
1/4 load - 1.0 gph
1/2 load - 1.3 gph
3/4 load - 1.7 gph
Full load - 2.0 gph

Generator B

No load - 0.4 gph
1/4 load - 0.7 gph
1/2 load - 1.1 gph
3/4 load - 1.6 gph
Full load - 2.0 gph

Basically, some engines, diesels in particular, scale fuel consumption more linearly with load. The gas engine uses 50% of it's full load fuel consumption at 1/4 load. The diesel reaches 50% of full load consumption just before 1/2 load, using only 35% of its full load consumption at 1/4 load, which is much more efficient, and a much more linear usage curve.

The more linear the usage curve of an engine, the less it hurts FE to run an overpowered engine at light load, allowing a car to go fast when needed, but still return good mpg in gentle driving.

My Jeep, for example, has a very non-linear consumption curve. I actually get worse mpg if I accelerate gently around town. If I get on it harder, and let it shift around 2200 or so, allowing me to get off the gas sooner, it can make the difference between 11.5 and 12.5 mpg with otherwise identical driving in the city. Of course, this doesn't work with other cars in front of me downtown, as they typically crawl up to speed so slowly the tranny shifts at 1500 - 1600 and I'm barely touching the gas at all.