The Amocat- 2005 Tacoma
 

Edit:
To make this thread easier to follow and so that you can bypass my rambling, I decided to post an index up at the front for you to link to completed major projects on the truck. Also I have the original and a recent picture of the truck so you can see the changes that have been made.


Rubber Air Dam:
http://ecomodder.com/forum/showthrea...tml#post454423

Initial Half-Aeroshell Construction:
http://ecomodder.com/forum/showthrea...tml#post473102

Finished Half-Aeroshell:
http://ecomodder.com/forum/showthrea...tml#post480010

HVAC Air Intake Pest Screen:
http://ecomodder.com/forum/showthrea...tml#post481678

Electric Fan Construction/Swap:
http://ecomodder.com/forum/showthrea...tml#post483654

Fender Flare Removal:
http://ecomodder.com/forum/showthrea...tml#post494844

Full Aeroshell:
http://ecomodder.com/forum/showthrea...tml#post511880

Back to the regularly scheduled post:
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Hello all,

Figured it was time to start my own build thread for this truck. Truck is a 2005 Toyota Tacoma Access Cab, 2.7L 4 Cylinder, 5 Speed Manual, 4x4. The truck is my daily driver, which includes long commutes to work, trips hauling construction materials, and driving off road. I engage 4x4 an average of 3 times a day to navigate unpaved roads. My current baseline from my fuel log is 26.7 MPG, based on 23 fill ups.

My first goal is to consistently exceed 30 MPG, while maintaining or improving the truck’s capabilities. I plan on achieving most of this through aerodynamics, as the truck has a factory Cd of Cd 0.394.

Mods that I have already done are: First mod was switching all long term fluids to Amsoil synthetic, including front diff, rear diff, transmission, and transfer case, and changing engine oil to Mobil 1 synthetic. Second mod was changing the tires, went to Michelin LTX M/S2 LT 235/85R16 mounted on factory Toyota 16” alloys. (Note factory was P 245/75R16 on steel wheels.) This nets about 0.5” ground clearance, 4% gearing reduction, and corrects the speedometer to within 1MPH at 55MPH. Going from P rated tires and steel wheels to LT rated tires and alloys only netted a 5lb increase in weight, but it increased the rotational inertia of the wheel tire combo by 15% due to the weight being farther from the center.

The next step for this truck is an aerodynamic bed cover.

Nice to see a build thread for your vehicle. Have you thought about a grill block or air dam?

Wow, fast reply. Those are both on my list, just a little farther down. I am going to do an air dam, but it is part of a bigger project on the front end because I want to make it quickly removable for rough roads/trails. I don't want to do the grill block until after I swap to electric fans, and get a feel for the temperature baseline.

Let’s jump right into the bed cover. I have run through many options on bed covers, and have admired all the great looking aeroshells that members on here have made. Truck has a factory Cd 0.394. I am leaning towards doing a cab wing and tonneau cover combination. That would give me the most flexibility as far as still loading tall things in the back half of the bed that a full aeroshell would not allow. I think it would also retain the best visibility.

I will present my initial plan below, and then I would like your comments on how to make it better and/or easier to construct.

The Tacoma has a 6’-ish bed. The “cab wing” would be built similar to a half aeroshell, and only cover about 3’ worth of bed. What I have to start with is a snugtop xtr bed cover in rough shape I picked up for cheap. It was designed for a 5’ bed, and I am going to hack up into the half cover. You can see from an attached photo, it has a two part window; my plan is to remove the back window and end the cover right after the current fiberglass divider between the windows, forming a 3’ish bedcover. The front window and good visibility will be retained.

Next the roof will get removed, the front most part with the bump up will be removed, and the middle and back of the roof will be reinstalled starting in the front on a curve following the AST-II template in side view. The sides and front of the cover will be left intact. This will form a gap between the top sides of the cover above the windows and the lowered roof. This gap will be prepped and fiberglassed, tying the two together. I have attached a sketch of what I am proposing.

Obvious downsides are little plan taper and the vertical extension on each side of the cover is less than ideal. Upside is ease of construction, and a “more normal” appearance, as you will not see the tapering roof section from the side, only from the back.

I am unsure on the best way to address the tonneau cover, as presently the template AST-II does not touch the back of the tailgate when overlaid. Also any half tonneau would need to be quickly removed and stowed. Options are to install a half tonneau at present elevation, raise it up to touch the template, or extend it back to touch the template.

Edit: The template looks off in the front, but it will be correct when I replace my front shocks and raise it up a bit, plus I am accounting for additional dead load in the back of the truck.

Since you off-road, you'll need to account fer frame/bed flex so the shell doesn't impact the cab. On my aero cap journey, I made some gap covers that slide over the cab and cap. I ended up incorporating the covers into my aero cap. ;)

Can't wait to see how you progress! :D

box detail
 

Does the Taco have holes in the rail tops? If so,you could attach stanchions in those,then attach the tonneau to the stanchions.Air Force button-release lock pins would be ideal.Fast!
If you blistered the tonneau you could loft the upper surface up close to the AST.Without it,or some kind of spoiler,the air may overshoot the tailgate area completely.
http://i1271.photobucket.com/albums/...ohead2/206.jpg

Given your materials and goals, that looks like a reasonable approach.

How about a full tonneau that overhangs the tailgate; but has a sliding track with roller bearings, like a high-end cabinet drawer; so it unlocks, pulls back and locks to make a half-tonneau/Bonneville spoiler?

Simple first mod, use pipe lagging to fill in the gap between the cab and bed.

BamZipPow,
Since I am reusing the front part of the original shell, I believe it will hold the shell about an inch or so away from the back of the truck, so that should allow sufficient room for flexing side to side. I saw what you did in one thread with the flexible baseboard as gap filler and would like to do something similar.

Aerohead,
No holes in the bed rail tops unfortunately, but it has a factory track on the inside of the bed that I can mount a bracket to. That bracket could hold a quick release. I would like to not inhibit visibility too much in the back, so I don’t think a blister would work for me. Since the tonneau needs to touch the template in the back it needs to go rearward, up, or both.

Freebeard,
Thanks for the encouragement on the cap design. I hadn’t thought of a sliding track, that is a good idea, but I don’t want to go to a full tonneau for bed utility reasons.

Oldtamiyaphile,
Yeah, I have done pipe insulation as a gap filler on one of my other trucks, need to cut pieces for this one.

What I am thinking now is I could do two tonneau pieces flush and have one just in front of the tailgate covering the last part of the bed and one sticking out just over a foot behind the tailgate to touch the template, but then I have the overhang to contend with. Alternatively I could do just the piece in front of the tailgate if I raised it up about 5” and leaving it open below I could still see above and below it, so visibility wouldn’t be that bad. Either way they would be hinged or quick released so that I could transition to a fully open bed in the back as necessary.

Nice!

I have found that a tonneau cover, by itself, effectively did nothing for aero on my Dakota. Looking at the template overlay, it would appear to be because the airflow over the Dakota does not come near the tailgate.

You might want to experiment with the cab wing by itself, first. Then, once you demonstrate an improvement in aero with the cab wing, you can experiment with a partial tonneau.

Thought I would update this thread with my progress. I took some measurements of the truck and the cap. I stripped all the unnecessary windows, liner, and hardware off of the cap. I then chopped the majority of the roof section off of the cap. I still need to chop the front bump-up off, just ran out of time. Also the side cuts are not finished; I will trim those to make one straight line. I ran into one snag, as the roof section was doubled and reinforced. I was expecting it to just be a single sheet of fiberglass that I could coax into a gentle curve. I will either have to remove the reinforcement or just use another material for the roof. Anyway, here are some shots of the progress, ignore the dust from the sawzall.

A little more progress, figured I would update. I got the rest of the camper shell trimmed to size. I put the shell on the truck and traced a cut line, following the contour of the existing slope of the roof. You can tell from the photo I need to do some sanding. I got a new side photo of the truck from a distance, and did the requisite AST-2 overlay.

After much study, I believe I have decided to make a cardboard form in the shape that I want for the roof, and then layer fiberglass over the form, to make the cap one solid fiberglass piece when I am completed. This is a little more difficult than I really wanted, but the easier/simpler ideas aren’t turning out as I had hoped.

http://ecomodder.com/forum/attachmen...9&d=1410349044

http://ecomodder.com/forum/attachmen...0&d=1410349044

http://ecomodder.com/forum/attachmen...1&d=1410349044

http://ecomodder.com/forum/attachmen...2&d=1410349044

Simple usually does not turn out to be simple, does it? ;)

Thanks for the updates. Thanks especially for the picture of the aero overlay on top of the truck. I have the same body shape (2012 Access Cab) and now I can stop wondering how much I'd improve fuel economy with a bed cover. :(

It needs plan taper, so you might keep cutting. If you could remove those plastic windows and use an electrical heating tape to put a diagonal crease in it, and notch the fiberglass to bend it for the increased tumblehome then pull the lower corners in a bit — then it would conform to The Template.

Alternatively, cut the top of the window at 22° and put as much compound curve into the new construction as you can. Instead of fiberglassing over cardboard (unless it's an egg-crate there's lots of opportunity for grief) think about buying preformed fiberglass panels and just glassing the joins. Use thin H-channel to capture the edges, drill holes and sew it together first.

IMHO, of course.

wdb -- That doesn't look bad. Two fiberglass rods in an X and some vinyl-coated fabric for a boattail erected on the tailgate. Why not?

Wdb,
You should probably take my aero template overlay with a grain of salt, because my truck is not 100% stock. I have 235/85R16 tires, so with an approximate 1” increase in diameter my truck is 0.5” taller than stock. I also have Bilstein 5100 shocks raising the front of the truck 1.75”. Lastly I only have the 3 spring leaf pack in the back (2 leaf + overload), so if you have the 4 spring (3 spring + overload) your back end may sit up higher empty.

Freebeard,
Thank you for your input, I hear you loud and clear. I have extensively deliberated the lack of significant plan taper in my plan, as well as the two side vertical “wings” that will be created at the back as the top tapers and the sides don’t. This is obviously far from ideal. Unfortunately, the windows in the cap are actually glass, not plastic, so I don’t have a way to cut them. I want to try to maintain visibility, so I want some kind of windows. I am really trying to avoid taking the cap all the way down to a base and starting over, but to correctly apply the template, I realize that is what I would have to do.

What I don’t have a good feel for though is how much worse will my less than ideal implementation be than a true cab extension half template. For example, rule of thumb “internet” data is a regular cab height camper top is good for 5% to 10% drag reduction, and that has no taper whatsoever. Similarly, regular bed covers are usually attributed around 5% drag reduction. These are both obviously far from ideal. An aero shell is often credited with 10% to 20% potential drag reduction.

I am assuming a mongrel shell, with no plan taper, is somewhere between the regular camper top and the aero shell, but we all know about assumptions... And then since it is only a half mongrel shell….

Good thoughts on the construction technique though, do you know of a source of fiberglass sheets? I may re-look at my old roof to see if I can remove the reinforcement without destroying the top panel.

Those pieces of (probably tempered) glass aren't doing you any favors. Get a piece of acrylic and cut it on the diagonal.

Once you settle on the overall form, the final Cd figure will depend on the details — i.e., the radius of the edge. A hard edge is worst. The rule of engineer's thumb is radius equals 4% of overall width, or less than 4" minimum.

The sheet acrylic can be cold rolled (I'm pretty sure) so roll the hypotenuse and leave a flat triangular tab to fit in the lower front corner. Then rely on fiberglass to fill in the gaps.

I'd have to Google for a supplier, here:

https://www.google.com/search?q=fiberglass+sheet++stock

It looks like it's called fiberplate.

Sorry for the long post, I type a lot.

Well, after gathering all the parts, over the weekend I finally put together an air dam on the Amocat. I used rubber hay baler/ conveyor belt, two pieces of aluminum flat bar, stainless steel nuts and bolts, and blue Loctite for assembly. Two 5/16 nuts and bolts hold the aluminum sub frame to the truck frame. I am considering this version 1.0, as it is not perfect and I can already see several tweaks that I need to make.

The conveyor belt is 7” tall, but only 4”-5” of it are hanging below the existing truck frame where I mounted it, and the remainder is blocking the front of the truck frame and the upper gap between the bumper and truck frame. The bottom of the air dam is basically at the same height as the low point on the truck, the bottom of the independent front suspension skid plate about 12”-18” behind where the air dam is mounted. The air dam is designed to stand up to abuse and being drug off-road.

Initial impressions are that it is definitely doing something, but I don’t know if it is appreciably lowering drag at this point. It is really hard to tell since I installed it right at a cold snap, and the next tank had some off-road driving on it. I did a short fill this morning just to try to get a feel for any changes in fuel economy, but my results are within measurement error. Two noticeable effects were significantly lower lift on the truck and significantly lower wind noise from the front tires. The truck definitely felt more planted in turns. I think it is also forcing more air through the radiator/engine compartment.

There are some issues with this design that I am aware of, as follows:
The very center and the two sides have some curvature, but the remaining section is very flat. It would be better if the whole thing had a gentle curve. This was a compromise I made for easy mounting, and to not interfere with the existing tow/tie down loop.
The two sides stick out to far. I built the aluminum subframe out of two 72” pieces, and didn’t want to cut them down until I had it built and installed, so the air dam ended up flush with the outer edge of the tire. Knowing the air is traveling at an angle at that point, the air dam should end before the edge of the tire. Right now, I believe I am throwing the air too far around the side of the truck.
The lower edge is flat/sharp. It would be best to have some amount of lip here to hold the air, and some amount of radius to smooth the transition point.

So here are changes I intend to apply for version 1.2 of the air dam:
Use washers or spacers towards the center to increase the slope on the two flat parts of the air dam. I am going to be limited by my tow hook, but I can get some more slant to it than what I have now. A full curve imposes mounting, tow hook, and off road issues, so that will have to wait for version 2.0.
Bend a sharper turn on the outer edges of the aluminum to tuck it up more towards the center and end the air dam sooner. This should keep the air from overshooting the tire.
Rivet some rubber hose on the bottom to create a lip and radius, while still maintaining durability and flexibility. I need to test some sample pieces first.
Reading Hucho’s book, and looking at posts on this site, I am considering making the air dam shorter in the center, and leaving it the existing height near the edges.

So give it to me straight, what are your thoughts and opinions?

In other news, I cut the windows out of my camper top, and I have sketched out some designs for a full aeroshell camper top. Once I get my air dam tuned up where I want it, I will probably begin working on this in earnest. I also got my ultragauge mounted, still need to mess with the gauges I want to appear and learn the truck’s baseline.



http://ecomodder.com/forum/attachmen...0&d=1415191505

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I think it looks pretty good. I'd probably paint the aluminum personally. Other than that, I think it would be better if it were farther forward. I understand that interferes with the tow hooks though. Lots of OEMs put their dams back farther like you did though, so there still must be some benefit.

It's looking good so far.

I like conveyor belting as a material, but I've only ever used it in conveyors. Is the edge finished or cut? What widths were available to you?

The bump in the center may stiffen the lower edge more than a smoother curve would. When you re-curve the outer ends would be a be good time to add triangular filler pieces.

I think you're on the right track with the camper shell. Are you still going to form it from cardboard? How would that work?

Daox,
I definitely agree, the aluminum needs painted. I am going to wait until I am happy with the performance so that I don’t mess the paint up adjusting it. Luckily since my truck is a base model flat black will help it blend right in. I had seriously considered putting the dam on the bottom of the front bumper, but in addition to the tow hooks I was afraid it would get damaged easier off-road.

Freebeard,
The edge is “semi-finished”, i.e. it isn’t ragged or anything. It cuts pretty clean with a sharp knife. I bought the belt at tractor supply, there was only one size available there, 7” wide 15’ long.

Yes, the bump is there for stiffness reasons, without a significant curve side to side the wind would blow the bottom edge up under the truck.

Good idea, I will add filler pieces to my V1.2 to do list.

I am torn on how to build the camper shell, I go back and forth on making a removable form from cardboard and tape, and later removing it leaving the fiberglass skin. The other option is to make a permanent form out of XPS foam, and fiberglass it on all sides, making a solid structure, similar to a fiberglass surf board. I have the materials to do either. I think the foam would be stronger with less fiberglass, so lighter for equal strength. I think the foam would also be harder to build, but I am not sure. The cardboard/tape/junk form buildup sounds fairly simple.

My plan on the camper shell is a two piece hinged or hatchback design, so part of the roof would be removable for carrying tall objects. I also want windows in the back and sides. All of that adds significant complexity to any design. I have some concept sketches, I will probably upload a design in a few days.

I like the lip! Location-wise it is where the folks at GM put it on the upcoming Colorado; interestingly, some pictures show that truck with the lip and some show it without.

http://image.motortrend.com/f/roadte...-z71-front.jpg

http://www.blogcdn.com/slideshows/im...71-005-a-1.jpg

Sometimes they just want a good approach angle. The truck's up so high it probably wouldn't hurt to push it forward. Maybe scoot it a half inch at a time and see when it scrapes...

Anyway, the build quality looks pretty good :thumbup: and I'm interested to see how that aero cap comes along.

Wdb,
The older information and older pictures of the Colorado from about six months ago (when I was seriously considering waiting for one) didn’t have the air dam on the Z71 models, just the base, work truck, and LT. Now it appears they have the air dam on all the models, probably for on road stability reasons. If you look on their website though you can still see some of the older photos up of the Z71s without them.

Sven7,
I looked long and hard about moving it to right under the front bumper cover. Since mine is rubber, it doesn't matter at all if the dam scrapes or drags, but since I actually offroad the truck a bit, I didn't want to risk dragging the aluminum subframe, since that could potentially damage the truck or puncture a tire if it came off. I could mount if more forward, but it would complicate the mounting significantly.

If I didn't offroad and want the clearance, the X-runner Tacoma has some interesting aerodynamic lower molding pieces on the front bumper, sides, and back that I would probably try to retrofit. Toyota has the 2WD Pre-Runner access cab at CD 0.394, but the 2WD X-Runner access cab at CD 0.357. So there are factory toyota bolt on fairings available that could reduce CD by 0.037. Nothing to sneeze at.

Well, I only got part of my V1.2 list done, so I am labeling this as V1.1 for now. I was able to reshape the outer radii into a tighter arc, and trimmed about one inch off of each end. This should keep the air from drastically overshooting the tire, but I don’t know for sure that I didn’t overcorrect and bend it too far.

Looking again at how close my tow hook is to my aluminum air dam frame, I was unable to increase the slope in the two flatter parts of the middle towards the side, so that idea was a no go for now. Further examining Hucho’s book and the many charts it contains, I decided to cut out the center middle of the air dam, 1” tall by 28”sloping to 34” wide.

Inspecting other charts in the book that had heights of air dams and placements front to back, my far back placement of the air dam appears to have some but not overwhelming impact on the available reduction in drag coefficient, but clearly had implications on available reductions in front lift coefficients. Honestly it’s already better than stock, so I think I can live with that for now.

Examining the charts in the book further, a front lip on the air dam was shown in the book with positive results, so I began testing attaching some pieces of rubber fuel hose to a scrap of conveyor belt to act as a lip when I ran out of time to work. I quickly re-bolted the air dam on, a let than five minute job.

Anyway, here are some pictures of V1.1 as I reinstalled last night. Based on some “coast down hill” type tests this morning, V1.1 appears to have slightly lower drag than V1.0, but there are way too many variables to know for sure right now.

http://ecomodder.com/forum/attachmen...6&d=1415363755

http://ecomodder.com/forum/attachmen...7&d=1415363755

http://ecomodder.com/forum/attachmen...8&d=1415363755

http://ecomodder.com/forum/attachmen...9&d=1415363755

http://ecomodder.com/forum/attachmen...0&d=1415363755

Good improvements. The notch in the lower edge is good because unpaved roads tend to have a high center. I regularly re-grade my friends driveway.

Insomnia struck again, so I got up early and put the tube lip on my airdam. I ended up drilling holes through the rubber tube, putting a rivet though the inside of the tube through the conveyor belt. I used a washer on the back side to expand the rivet into, so it wouldn't just pull through the conveyor belt. Made a pretty solid connection, and the fasteners semi-hidden from view.

I need to put something over the end of the tube to hide the gaping hole for cosmetic reasons. It is also getting about time to take it off and paint the aluminum. I am about ready to call this project "good enough for now" and start working on the bed cover.

Any thoughts, suggestions, or ideas are welcome though.


http://ecomodder.com/forum/attachmen...2&d=1415456913

http://ecomodder.com/forum/attachmen...3&d=1415456913

http://ecomodder.com/forum/attachmen...4&d=1415456913

http://ecomodder.com/forum/attachmen...5&d=1415456913

Expanding foam would work to plug up the ends of the tubing... ;)

Well, I removed the air dam, got the aluminum painted flat black, let it dry to the touch, and got it reinstalled yesterday.

http://ecomodder.com/forum/attachmen...7&d=1415619957

http://ecomodder.com/forum/attachmen...8&d=1415619957

http://ecomodder.com/forum/attachmen...9&d=1415619957

Looks good to me. :thumbup:

What's the reason for the tube lip?

Probably fer reinforcement... ;)

Sven and BamZipPow,

Support did have something to do with it, but a forward projecting flat lip (splitter) on the bottom of an air dam was shown in Hucho’s book in one example as achieving a slight reduction in drag. I am assuming because it is helping to contain the increased pressure from flowing under the dam and instead directing it around the side.

This tube acts like a lip, only with a radius in the leading edge. This also mimics a design I have seen on some OEM air dams that have a radiused bulge near the bottom, as well as some OEM designs for a front splitter that lead with a radiused edge. It also gives the air going around the car and under the dam a small radius to follow, which I would think would be better than a square edge.

But at the end of the day I don’t have a wind tunnel so this is just guess and check based on what I have seen and read from those who do.

Have you driven with it long enough to form any opinions yet? Any MPG differences, driving experience, wind/road noise, blahblahblah? Enquiring fellow Taco owners want to know! ;)

Wdb,

Good questions, I’ll address the MPG first. I have not done ABA, but I have been watching my fuel log intently to discern a FE difference. Unfortunately, my timing could not have been worse, as I installed the air dam right as the temperature dropped dramatically. Also my fuel log contains some tricky data, as most of the time I fill my truck with 87 Octane 90 Gasoline 10% Ethanol, but occasionally I get access to some 93 Octane 100% Gasoline, so many of the peaks on my FE graph are associated with that. Many of the dips on my FE graph are due to unusually large amounts of offroad driving.

Looking back through my fuel data, to avoid the 100% gas and offroad outliers, I will use six tanks from October 2nd through October 18th (next tank had 100% gas) as the baseline, and six tanks from November 5th (first tank with it installed) through 13th (today) as the test data. Note the temperature has dropped 20 degrees, from having morning lows in the 50s and 60s down to lows in the 30s and 40s. Also some of those tanks had V1.0 not V1.2 of the air dam.

In October, traveling 1812.928 miles using 70.015 gallons is 25.893 MPG. In November traveling 1114.568 miles using 42.633 gallons is 26.143 MPG. So the air dam is showing a roughly 1% increase which is within measurement noise, but given the 20 degree temperature drop, I don’t think the results are too shabby. So basically I like it, but let’s face it I am biased to it.

As for wind/road noise, there is a noticeable reduction in wind noise coming from air hitting the tires up front. The Tacoma’s had stock tire air deflectors which did ok when traveling straight, but the second I would cut my wheel very far, the noise would greatly increase. That has all but gone away. Note I am running 235/85R16 (32”) tires on stock wheels and have the front shocks raised up 1.75” so your results may vary.

For driving experience, the truck certainly feels more planted around turns, but that may just be my brain extrapolating a reduction in noise to better handling. According to popular literature, the truck should be experiencing reduced front axle lift, which is equivalent to increased downforce, and the handling isn’t all in my head. Anyway I feel better about taking the same turns at the same speeds.

In other news, I am refining my aero shell design, so that will get posted when I get something worth posting.

Well, I don’t know that I have an idea worth posting yet, but I started last night gluing pieces of foam together to make my aero shell. I cut a few wooden 2x4s into the gentle arch shape I needed for the top section, laid plywood over that, and started layering on ½” XPS foam using gorilla glue to hold them together. I then stacked weight on the assembly to hold the foam tight together, since the glue should expand as it dries. After it dries, the foam should hold the arched shape when removed from the form.

Also, the cold weather has killed my MPG. My last tank was my worst ever. Definitely need to check my tire pressures when I get home today, I am sure they are at least a little low due to the temperature swing.

Conveyer is such a neat idea. I scoured the junkyard to find a good fit my 74 wagoneer, but not a single air dam was in a good shape, ended up buying one on-line that match my width, and need to figure out the best way to attach it.
The hose at the bottom is good too, the same idea is present on OEM civic crx from the 80's.

The other try was the underbelly pan on the 85 Grand wagoneer, seen here during install, I used the bungee around the block...


https://lh6.googleusercontent.com/-i...106_162203.jpg

I used a drip pan fastened to the frame under the transmission and transfer case and covered a bit of the cat, great idea, but not so good when it is over 90F, the cat slowly warmed up the gas tank , and in the afternoon with temp in the near 100, the gas was so hot that the electric fuel pump could not draw gas due the restricted air flow under the carriage, pull over and chill out in the middle of Utah beetween Green River and Wellington... on the way back to SF....

But as you mentioned at the beginning the biggest improvement was the synthetic oil for the rear differential which netted a good 2 to 3 mpg, so from 12.5 to almost 15 and even 16 cruising on the highway 80 going East or West over a few tank refill.

As an update, I have gone back and forth fifty times on exactly how to do my aeroshell, which frustrates me to the point of ignoring it. I have finally decided on a path forward, which is to use as much as I can from the original shell I chopped up to put together a 1/3 shell right behind the cab. This uses the original pieces of the shell from the front, back, and roof trimmed down to size. This will also cover only the part of the bed that my toolbox currently occupies, and gives me enough room to easily access it. I got the pieces all cut out, but I need to change some lengths to make the cover follow my template overlay (AST-2). Anyway I posted up a mockup picture showing the modified front and back, the roof section bridges the two but I don’t have a picture of it yet.

The long term plan is to build a cover to cover the rest of the bed and hinge it off of this cover, but I need to just get something built and done so I am not focusing on this at all until the first part is installed and done.

Hey Windy,
Sorry I never saw your post until now. I can't take credit for the conveyor idea, I borrowed that from others on this site. The drip pan you used is a neat idea, hopefully you have resolved the gas tank heating issue. (I had a similar issue on my old car.)

Continued to work on my partial shell mock up. I changed the angle (steeper) and height (shorter) of my back piece to raise the back corner to hit on an AST-2 overlay. I cut the old roof section out some more to match and got the front, back, and roof all temporarily bolted together. After some tweaking and adjusting, I threw the mock up on the truck to double check the overlay.

Ignore how bad the overlay pictures are, it was dark out and I had to really wack out the camera settings to make the shell show up against the background. Also the camera was too close to the truck so the perspective was off.

The rough shape seems to basically follow AST-2, so I am decently happy with the results. The cab to shell transition could be smoother as it looks to be a fairly abrupt 6.5 degree change.

Next steps are:
Adjusting the side window openings to be larger.
Fiberglassing these three pieces together to remove the bolts.
Making something to transition between the window sides pieces and the roof.
Getting a more distant side picture of the shell.

http://ecomodder.com/forum/attachmen...3&d=1427480040

http://ecomodder.com/forum/attachmen...4&d=1427480040

http://ecomodder.com/forum/attachmen...5&d=1427480112

http://ecomodder.com/forum/attachmen...6&d=1427480112

Looks interesting to say the least! It may just be me but it looks as though yYour design study validates the flying buttresses on some Chevy pickups, and the Honda Ridgeline.

Did a little more on this over the weekend. I got a more distant side photo in good light where you can actually see the shell. Did the requisite AST-2 overlay and it looks like the back of my shell is a little low and the front a tad high. I attached the overlay photo.

I removed a bit more material from the front, maybe dropped it 3/8” to ½”-ish. I also cut some more material out around the windows. I was getting it mocked up to make the back part steeper to raise the back up around an inch when I ran out of time. I also found another piece of the original shell that I may be able to adapt into the window to roof transition piece. If all goes well, I hope to get a final mockup done and maybe start the fiberglass patching next weekend.

Well, I got my initial fiberglass patching done over the weekend and it has set up nicely. This was my first time using epoxy resin with fiberglass, it seems sturdy. The remaining tasks to do on this project are:

1. Make a curved transition from the top to the sides and finish making a lip for the side windows out of fiberglass.

2. Prep and paint the shell.

3. Install some acrylic/lexan windows.