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Old 01-06-2008, 10:49 PM   #21 (permalink)
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Originally Posted by Smoky View Post
I think everyone may be misinterpreting my comments. I am not trying to start any arguments I just want to assist in finding more ways to make everyones vehicle more efficient.
I'm just trying to help you out with forum forum etiquette here, so don't take offense. It would help without the appeals to nameless authorities to justify your arguments. If you are going to assert something, be prepared that someone will argue the point if they know it's not right. People here may be hobbyists but we take it seriously.

I know MetroMPG has bought at least one book on aerodynamics. Trebuchet works on HPVs while studying engineering (mechanical?). I'm an electrical engineer, and I've built a fuel economy simulator in my spare time that gets very good agreement with real world values. We've all spent man months in our spare time, researching fuel economy using search engines primarily. At the very least, I know I have and basjoos has, it is evident in his designs, and he has been thinking about this since the first fuel scare back in the 1970s. This particular site may be new, but we have discussed things together for over a year now.

Perhaps the difference in our approach to that of the automotive industry (which it appears you hail from) is that we expect that fuel prices will rise exponentially in our lifetime. 100%, 200%, 500%, 1000% increased real prices are not unreasonable expectations given human population growth rates.

Saving 5% in that environment is just not going to cut it.

Instead of asking the question "What can we do to make our current vehicles more efficient, given the driving styles of the average consumer?", we are asking the question "What is actually required to get from A to B with a bare minimum of fuel? Can we do that by modifying our driving behavior and vehicles? If so, how?"

The changes required are radical but effective, and not that difficult once you know how.
Quote:
I agree that aero is important. I do address frontal area in my other posts. In the auto industry we are under enormous pressure to reduce frontal area, reduce drag and weight.
If there is enormous pressure to reduce frontal area, drag and weight, then the pressure from the marketing department to make stylistically obsolescent cars in order to generate more profit for shareholders must be mind bogglingly gargantuan - on the order of that needed to create diamonds from coal.

If there wasn't, every car would be shaped like the prius or better. The knowledge of how to make an aerodynamic car existed back in the 1920s and 1930s.
Quote:
If weight is not a factor then F1 cars would not be using expensive and exotic materials. They will spend millions to save 1 gram of wieght. You can go to any entry level race series and see how they make their cars more efficient. They take out the weight. Aero is important but they are doing pretty much what you all advocate here (and I agree with).
F1 cars are about how to get across a distance composed of a number of curves in the shortest time possible, while staying within a set of rules. Fuel economy is about how to get from point A to point B while minimizing fuel consumption. Two very different things.

If you are trying to take lessons from competition, you would be better to focus your attention on things like the PAC-Car II, solar cars, HPVs, etc.

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Old 01-10-2008, 11:41 PM   #22 (permalink)
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That fast back crap won't help a bit, it will only add weight. A pickup truck already gets that effect by the turbulant air behind the cab with no extra weight.
Sorry, I have to correct that one, it doesn't completely create that effect, it causes air to go over the turbulent air, or "air bubble" but doesn't lessen the air wall that is behind the truck. the point is to cause the air to flow down the said "fastback" and create the smallest air trail behind you as possible. if it's traveling over the "air bubble" it's working more like those covers that make the truck look more like an SUV than a truck. Therefore you have a large trail of air behind you like my suv would make, but this would create a sedan effect, making only a small trail of swirling air behind you as tall as the tailgate is, instead of as tall as the roof line.

If you made that Boat tail, what would you make it out of? would be the question. Some would choose Coroplast, some would go with fiber glass. In any event, I think that it being a truck, with basically a wall for a window that even though you add 50kg's, you'll save about 80+ if your like me and drive about 85% Highway, 15% city. That's a lot. Look up Basjoos's aerocivic.

I know your just trying to say that, for most people who drive more in the city, it will actually hurt them more than help, but the ecomodders who will craft one themselves drive more on the highway, which is why they are doing this. The ecomodders who drive in the city will slim and trim down their vehicles.




Not trying to bag on ya or anything, but if you look at the cover, it's definitely not made from a metal, but more of a plastic or fiberglass application. For this guy, it saved him money, for the guy who lived deep in the city, will cost him money. That's why they're either DIY or Aftermarket covers (the non fastback ones that are square and turn a regular truck into an SUV) because if they were standard, it wouldn't help everyone. the ones that it WOULD help, buy them to do so.

I get what your saying. And it's a good point.
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Last edited by DifferentPointofView; 01-10-2008 at 11:51 PM..
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Old 01-11-2008, 10:32 PM   #23 (permalink)
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Differentpointofview,

Here is a little smoke visualization in the wind tunnel to back you up.

Brett
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Old 01-18-2008, 12:58 PM   #24 (permalink)
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It so happens, I have here in front of me the log of my pickup. It includes readings before and after the cap was installed.

The cap is a roofline-height model, so it doesn't stick up in the wind. It also isn't especially heavy, about 150-200 lbs. I can install it by myself.

Before cap: best mileage = 28 mpg. Avg mileage ~ 27.
After cap: best mileage = 37.4mpg. Avg mileage ~ 30.
Cap off for several months a few years ago:
Best mileage: 28.5mpg. Avg mileage ~27.75mpg.

All of these are in excess of the EPA's pie-in-the-sky estimates.

I don't drive especially fast, but people aren't shaking their fists at my dawdling little truck, either. Most of my driving is highway, the vast majority of it unloaded, in all weather.

In October, on its 20th birthday, the truck delivered 29.54 mpg. I wasn't even trying to beat the EPA, it just happened.
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Old 01-18-2008, 04:09 PM   #25 (permalink)
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Quote:
Originally Posted by bondo View Post
Differentpointofview,

Here is a little smoke visualization in the wind tunnel to back you up.

Brett
That's a sweet picture!
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Old 01-24-2008, 04:46 AM   #26 (permalink)
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I was very successful in gaining a few mpg in my previous vehicle.



The wheels were a impulse buy, had I have known about the affordable lightwheight wheels I have my my current vehicle I would have stuck with a 15x6.5 (11.5lbs each)

Its the only truck type vehicle I've ever had where driving with the tailgate down actually helped its fuel milage..

I once got almost 45mpg (all highway) after removing the spare, spare holder, tailgate, tonneau cover and rear bumper as an experiment.. I think it weighed in at 2190 with a half a tank of gas when I took it to sac raceway and weighed it..

I'd love to get another one of these and add a modern drivetrain to it say, something out of a Celica GTS.. power and mpg when I wanted it..
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Old 01-24-2008, 06:50 AM   #27 (permalink)
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That is an awesome little truck, I forgot about those. And was that with wide tires. Did that have a VW type engine if so a diesel would fit.
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Old 01-24-2008, 06:55 AM   #28 (permalink)
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it wore 235-40-17 on 17x8.5 wheels all around..

it had the Chrysler 2.2 in it..
The earlier 2 door coupe car version had the Peugeot or VW engines in em.

I kept the engine bone stock with 305K orignal (excluding 1 head gasket)
I sorta had to keep the engine stock because of the autoX class it was in..
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Old 01-24-2008, 07:43 AM   #29 (permalink)
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p.s.

got a picture of a "boat tail" ?
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Old 01-24-2008, 09:12 AM   #30 (permalink)
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When people here are talking about a boat tail, they generally mean the rear of a vehicle that tapers down from the top & up from the bottom (profile view) and in from the sides (plan view).

Phil Knox's truck is an example (post #22, above). basjoos' car is a more extreme example: http://forum.ecomodder.com/showthread.php?t=290

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