Easy Aero Fix? (Modding a pickup?)
 

Would it be possible to take a small truck and turn it into a mpg champ by a few homemade remedy's and an engine swap? The boat tailing part would be really easy since the truck is already divided in half. Some clear plastic and tape would easily make Cd improve dramatically, if you took plastic from the roof to the tailgate, and be much better than a full camper cover over the bed because it has a kammback effect right? you could easily lower it and do easy aeromods but... has this been successful?

Yes, I've been thinking this for a long time. On a lot of trucks, you'd get enough angle to make it meet at the top of the tailgate. On others, you might not.

http://metrompg.com/posts/photos/aer...oyota-trim.jpg

http://www.evworld.com/view.cfm?sect...le&storyid=870

Newton: you've got a class of vehicle in Australia not sold in North America that's ideally suited to this approach: the car-based "ute". (Correct me if I'm wrong.)

http://www.geocities.com/motorcity/p...mages/comm.jpg

Far better than modding a truck, since they're going to be lighter, lower, and will likely have better aerodynamics from the get go, even before the mods.

I wonder why people don't do that more often, especially for the ones who actually need the truck part, they could craft a removable kammback so when they need to load up they can do so easily. And for added ground clearance, you could get airbags *w/ on board air compressor* to raise the vehicle when needed, and lower it for daily use with the flip of a switch.

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.

If you want to better the aero in the bed area: use a tonneau cover and put a 6-8" piece of aluminum extending the roof off the back of the cab and tonneau cover over the tailgate. that should get you up to 2mpg at highway speeds with minimal weight. A truck cap with the extension off the back would also do.

Plug any holes in front, lower truck, add a front air dam, remove trailer hitch and replace rr bumper with roll pan, remove all extra weight. Get smaller mirrors. Use under-drive engine pulleys. tune up the truck. Increase gearing

But aerodynamics > weight, so I challenge that assertion.

In a wind tunnel, you are correct. I thought everyone was looking for real-world application. I don't mean to be a smartass, sorry.

I have worked with many efficiency consultants, aero scientists and powertrain engineers in my field of study. I believe I have a good understanding of the basics. I will admit I am not an expert! I do however like helping out anyone that would like input with the limited knowledge I have. Share the wealth and we are all better for it!

*I don't know if this will post correctly, I am a forum newbie so please cut me some slack!

Sorry to keep beating this to death.

Apples to apples:

Honda Insight:
1,9xx pounds
.25 coefficient of drag
70 mpg EPA (old math)

Toyota Prius:
2,9xx pounds
.26 coefficient of drag
60 mpg EPA (old math)

What's the difference? weight.

Replace all that hybrid crap and motor with a VW 1.9 turbo diesel running bio and it would be hovering closer to the magic 100mpg than either of these.

There are lots of other differences besides weight.

If you compare the 2006 models, both with CVT, using new EPA ratings you get this:

Insight ------- Prius
47 MPG --- 46 MPG

Also the Prius has more frontal area than the Insight.

You do know that force of drag also has a frontal area component? Drag coefficient is only useful to compare shapes.

http://upload.wikimedia.org/math/7/9...37cc9d4d7e.png
CdA = Drag Coefficient * Frontal Area

Insight 5.1 square feet

Prius: 6.045 square feet

mpg difference: 16.6%
CdA difference: 18.5%

The other thing is that if a person is that concerned about fuel economy, he often learns to drive correctly. This means that more chemical energy from fuel is going to push air out of the way (and a little to deform tires, but only a little), and less to heat up brake pads (or the engine/exhaust gas with engine braking, or heat up the battery with inefficient regeneration).

If you eliminate braking, the only factor weight will play is in increasing rolling resistance, which is minimal at most speeds a car will travel in comparison to aero. And note virtually everyone here is decreasing rolling resistance by inflating their tires. 45-60psi would be usual. So aero is an even larger factor.

The "fast back crap" will reduce drag by probably 20-30%. It will add maybe 50kg, at most - or 2% of the weight of a typical truck.

Damnit basjoos, stealing my thunder! :D

That we do!

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.

There are 2 different threads on this exact same subject and I have posted on both.

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.

I think nearly everyone on this forum is on the right track with regard to aero. Because of this I have chosen to center my comments on the weight issue. I don't claim to be an expert.

For the driving most people do, 60% city 40% highway, weight plays a major role in reducing efficiency. In city driving speeds rarely get over 40mph. Most driving involves stop and go. The heavier the car the more energy it takes to get moving. Once the car is moving the role weight plays is reduced and the importance of aero increases.

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).

Reducing weight is one of the easiest and cheapest ways to increase efficiency.

Again, I am not trying to argue or disagree in any way and in fact I completely agree with your comments. I think everyone has something to bring to the table and everyones opinion is worth consideration.

Another comment, not to aero bash, just to inform.

Be careful with the boat tail trick. Many times this will make the car less efficient. Many of the aero scientists I have worked with really push for a 'chopped off' rear end to to help meet the aero requirements. They comment that several cars benefit from this. Examples they use are: Nissan 300 ZX, Honda CRX, Honda Insight, and Toyota Prius.

Again, I am just passing on info and not trying to discredit anyone.

Only factor??? :p

If only the world was flat, my mileage would be so much better...

Increased gravitational potential energy is only wasted if it goes into brake pads, or if your car is going a lot faster on the downslope than you ordinarily would drive. Hills are like perfect batteries for storing energy.

In the ideal world, all traffic lights would be at the crests of hills.

You do realize that if you put a boattail on the rear end of a truck, it starts to look an awful lot like the rear half of a Prius, CRX, Insight... etc? In addition, you can enhance flow separation at the back of the boattail you have just made with a little extra overhang.

I've never heard of a boat tail making a car less efficient. It's just that the advantage is proportional the the area where the boat tail shape terminates. In other words, since the lines on the usual car result in flow separation over the entire back half, having a sloped back end so that the flow doesn't separate over the entire rear profile is an improvement. The Prius would probably be more efficient w/ more of a boat tail, but the improvements would decline asymmetrically compared to the increase in length and drop in usable area.

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.
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.
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.

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.


http://metrompg.com/posts/photos/aer...oyota-trim.jpg

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.

Differentpointofview,

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

Brett

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.

That's a sweet picture!

I was very successful in gaining a few mpg in my previous vehicle.
http://i4.photobucket.com/albums/y10...98fORIGNAL.jpg
http://i4.photobucket.com/albums/y10...T/MVC-273S.jpg

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..

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.

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..
http://i4.photobucket.com/albums/y10...LET/engine.jpg

p.s.

got a picture of a "boat tail" ?

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

I beg to differ about the "fast back crap." Mine works nicely.

Weight is important but if you intend to use a pickup as a pickup, it becomes a special case.

Trucks are for hauling stuff. Trucks should be evaluated like aircraft - loaded to max gross. If that is the case, you can remove weight from the truck but you don't remove any weight from the vehicle. You just add more payload capacity.

True that! Makes me angry at the people who use their trucks like a car. Use it like a truck!!! Instead of spending money to lower it, just buy a beater geo or honda, or toyota!!!

I'd say it's usually cheaper to run one truck as a car than to run two vehicles. Besides, my truck's fuel ratings according to www.fueleconomy.gov are nearly the same as your jeep's. My city rating is 1 mpg better infact! :D

I use my truck like a car when i'm not using it like a truck..

Do you use your SUV like a car when your not hauling around people?

You could be getting twice the mileage with a mid size sedan that can do the same thing your 2wd Jeep is doing.

Its not cost efficient to own 2 vehicles unless absolutly nessesary,
then your paying insurance for 2 vehicles, and ones just sitting..


Now if you had a large F150 gas 4x4 that you used to haul stuff, a economical car would definatly be a good deal..

I'm getting a consistant 29mph in my truck and it definatly gets used as a truck when needed..
http://i4.photobucket.com/albums/y10...k/P1020191.jpg

I just hit the switch to let all the air out of the rear helper bags to scare a cat in the parking lot lol. thats why its sitting getteo..
http://i4.photobucket.com/albums/y10...a/P1030627.jpg
http://i4.photobucket.com/albums/y10...a/P1030626.jpg
http://i4.photobucket.com/albums/y10...k/P1030885.jpg

Howabout you, are you using your SUV to its fullest to and from soccer practices ;) j/k

yea, I blew a shock ealier this year using it like a jeep should be used. an suv or truck that never sees mud should never be owned.

And when I said truck, I meant both SUV's and trucks, most people around here call suv's trucks anyway since their big and tow stuff. When I got my Jeep it just sorta happened. it was cheap, and I needed a car to go to school. I just actually use it more than just commuting.

Yea, but your getting 20 or less mpg and I'm getting now 22's. Chris D. is doing best though at 34% over EPA.

Just wondering, but do you have any picks of it caked in mud?

Depends on the costs really. For me, comparing my pickup@1,000 miles and 27mpg to my VW@9,000 miles getting twice the mileage shows a cost difference of more than $500. Since insurance on the extra vehicle is only ~$300+/year, it's clearly cheaper to have another more efficient vehicle for my needs. And, since I only need the pickup periodically, I don't have to pay for coverage year round, maybe just for four months out of the year when I use it, so now I'm saving over $700 thanks to having a vehicle that's twice as efficient.

being that your ZJ is nothing more than a 2wd open diff, all your destin for is the occasional muddy puddle hopping, and thats hardly usefull..

I take my truck to alot of places most 2wd vehicles shouldn't go..
But lets not make this a pissing match..
Your Dakota (I mean Cherokee) is more than useful.. :thumbup:
http://i4.photobucket.com/albums/y10...w/Image016.jpg
http://i4.photobucket.com/albums/y10.../dirttaCO2.jpg
http://i4.photobucket.com/albums/y10...058Fmodded.jpg
http://i4.photobucket.com/albums/y10...1030378md2.jpg
http://i4.photobucket.com/albums/y10...t/MVC-825F.jpg
http://i4.photobucket.com/albums/y10...sdoffroad2.jpg

:thumbup:

lets see your muddy pictures then, your turn ;)

True. I've got to start figuring out how to mod this beast of mine. I've got a canopy on it... I'm thinking this summer I should see if I can make a tonneau cover like Chris has, they seem to be the best option to make the back of a truck more aero. By the way... Thanks Chris for putting up stuff like that! There's not a whole lot on ecomodders for DIY mods specifically for trucks. I think that would be a neat project, although I've never worked with fiberglass.

Roflwaffle, That's cool you can get part-year insurance. I haven't come across any insurance companies that do that around here. Although I haven't searched that hard. I should look into that... I was thinking about getting my motorcycle license and buying a little bike for getting around during the summer.

It's kind of a pain, since my company requires that the money be held until the end of the term if I decide I don't want to use the whole six months, but I'd rather have ~$100 in a few months than end up paying all that for a vehicle I'm not using. I think brokerage places like e-youknowwhat-surance and similar would be better since they're a month at a time even if they're a bit more expensive and not as trusted.

I just read about some stuff on the internet in reguards to
fiberglass and went for it, hit or miss its a win win learning situation.

try chopping that canopy up in a fastback style setup.
Bondo has started something thats quite good..

aero shells for trucks..:thumbup:
the stuff with the Tundra and F150 are his, the rest is just sorta thrown in there..
http://s4.photobucket.com/albums/y10...ma/AeroTopper/