nissan kingcab aerocap
 

here is the WIP of the aerocap im making for my nissan pick up.

it is made out of a solid wooden frame and covered with thin 3mm mdf panels.
i designed the plans by making a 3d model using google sketchup, it really helps alot when you have plans of wich you know they are 100% correct, as it is rounded from every side it would be impossible to draw accurate plans by hand.

as the surface is not 100% smooth i decided to smooth it out using plaster, time will tell if that was a good idea.

next is to sand the surface smooth and then cover it with something to make it solid and watertight. i was thinking of fiberglass sheets covered with epoxy resin. the problem is that i have lots of fiberglass, but can't find any epoxy or polyester resins over here in belgium.
all i could find was 1.5 liter of epoxy resin for making walls watertight, not sure if that will work and i doubt it is enough (ive done a small test today on a peice of mdf, will see tomorrow if it works)
any suggestions are welcome!

another problem is that i had to leave the vehicle outside for 1 night with the wooden frame on it, i had covered it with a plastic seal anchored with heavy stuff, but there was a heavy storm that night and in the morning the wood was soked. the result is that the wood has expanded and i cannot lift the cap off the bed anymore as long as it's wet, because it is fixed with 4 long bolts and the wood has expanded so they are impossible to remove atm.

since i took those pics this moring, i have already filled all the holes in the front of the vehicle with metal sheets, except for the grill.

by removing the mud flaps, the roof lights and by adding an aluminium bed cover, i have already gone from 10 to 8.7 liter/100 km

Nice work!

very sweet.

done!

http://ecomodder.com/forum/attachmen...1&d=1234082660

after 3 weeks of hard spare-time work, frustration and sweat, i can finally say it is done!
im verry happy with the result, even though up to the last second before putting it on the pick-up i was almost sure it would fail.

construction:

-first i measured the the whole rear of the truck and made a model of it in the 3d program "sketchup". then drawing a perfectly rounded shape on it was relatively easy. then i made some sort of wireframe and turned those into 3d wooden beams. then all i had to do was draw down and measure each part and just make it for real with wood.
each day i made the plans for some of the parts and built them, all this was relatively easy and fun and took about 3 days with a few hours a day.

-then i assembled all the parts and found out i miscalculated 6 small beams, that i rapidly remade. the structure is quite large and assembly was tricky at some points but it all went fine in the end.

-then i placed the whole on the bed and started sanding it smooth, a verry effective tool was my electric "planer"?

- then i cut out thin MDF wood sheets to fit each part and screwed them on, the bending ability of these sheets was stressed to the absolute maximum in some parts, but they held.

-then i realised that especially the sides were verry un-even, as the panels would bump inward at some points. so i filled those bumps up with regular plaster.

-then i sanded sanded and sanded again for a smooth result, and then i brush painted it with a primer for the polyester. result:

http://ecomodder.com/forum/attachmen...1&d=1234082660

-inmediately after that i began mixing the polyester resin and cutting out the fiberglass sheets. i did square meter by square meter, but i tell you it was a nightmare, all the fibers kept clogging onto the brush as soon as i touched the surface. it was only at the last two square M's that i found a technique that sort of worked. i swored never again to use polyester in my life.

http://ecomodder.com/forum/attachmen...1&d=1234082660

-once that was dry i started smoothing it out and sanding it, i used pretty much every tool one can immagine. the most effective for cleaing up the fibergladd gloggs was to scrape the surface with a handsaw, and the smooth it up with the metal grinder and a special sanding disk.

-the result was truly horrible, with craters, bumps, airbells everywhere where there had not been enough resin. so i filled all that up with universal filler. the result of that was acceptable, but not smooth enough to my taste so i repainted over that the polyester primer that was left, and made the huge mistake of painting over some epoxy resin i had bought by mistake. probabaly because it was freezing, it did not dry even after 24 hours, so i had to wash it off with water (wich went realtively easy though)

-then i could finally start painting, first sprayed 2 layers of white primer after each layer i sanded the surface softly again. and then 3 thin layers of black glossy paint.

even then i was sure it would look to bad to be used and i was certain it would fail because it was not 100% even and there were lots of bad spots. but to my big surprise it looks really good once on the vehicle!
http://ecomodder.com/forum/attachmen...1&d=1234082660

http://ecomodder.com/forum/attachmen...1&d=1234082660

edit FYI, the total cost was under € 150, the most expensive part was the polyester resin, fiberglass, primer and hardener for 5 sq meters. that alone costed € 70.
then come all the paints, filler, plaster and wood. altough i bought way to much of those and now i have lots of left overs for future projects.
the price is still acceptable i think in regards to the fact that this is probabaly the most viewable and effective eco-mod to do for a pick-up

first findings: the first noticable results were kind of unexpected :D

-the first is the priceless looks on the faces of most men and mostly other 4x4 drivers that i pass by. and i admit that i really love the looks the aerocap gives to my vehicle. instead of being another bland pick-up, it now looks like a classy sports vehicle (even though these pics don't really do it justice.)

-the second more serious result was also somewhat of a surprise, i never thought before that my pick up was noisy or shaky on the highway. but it now feels like driving a car, you really notice after the first KM how silent and stable it now is.

-and the most serious finding is that i can now coast down 8-10 times longer than before. the highway exit i take to go home is at the bottom of a valley, after a 2-3 km downward slope. before i could only coast down in 200-300 meter jumps and had to accelerate again to keep speed. but with the cap i can coast down for the full 2000 meters, take the exit and arrive at the national road with enough speed that i need to brake quite hard on the engine!

i will report the fuel economy as soon as i can give reliable numbers


btw, i have also shut down all the gaps in the front (the grill one is just for testing now) without any effect on engine temp, though it is cold outside.

i also started making a wheel cover prototype, it is just set in place by hand and is not really attached. but it is made of metal and is quite heavy, so im too scared that if these came loose they could kill, so i abandone the idea for now untill maybe i can make plastic ones.

http://ecomodder.com/forum/attachmen...1&d=1234085358

next on my list was making a front airdam, but i had an accident last week (i rammed i VW fox in the side after it ignored a stop and threw itself in front of me. the car is damaged to the side, and my left front bumper is pushed back 2 centimeters. so ill wait for what the insurances will do before touching the front) a good example of how hypermiling can save money in other ways ;) as i was respecting the speed limit on a road where most cars go over. thats how i nearly have any damage. btw, the lady driving the vw, had her license since january 09 ... :p

so i think i will now start making covers over the gaps around the wheel well
http://ecomodder.com/forum/attachmen...1&d=1234085358

Great work!!
One question though.. Does the loss of visibility through the rear screen bother you?

That looks great!

It almost looks like a canvas cover, like a military vehicle would have over the back of a truck, except black.

Good luck on the insurance stuff, maybe you can get some extra money out of it to help cover the cost of the cap :D

thank you guys!

i feared the reduced visibility would be a problem, especially since 2-seated pick-ups have the best all round visibility you can get.
and before finishing it i was already thinking of buying a rear view camera or at least parking sensors. but im not sure anymore if i really need that. i can still back it up at night through the gate as fast as i could before.

i even thought of making some sort of rear-view periscope through the roof, it is techincally possible :D

with the insurance stuff, who knows they will buy me a new bumper, the chrome one has light dents on it and is pushed back somewhat, it's hardly noticable on the pictures. but if i also get a new black plastic one, i could use the old one to experiment with an airdam/splitter ;)

That looks really good on the truck. Good Job!

:thumbup:

Nice work!

I wouldn't put too much hope in the air-dam idea however. Since your truck is so high, it's not really going to do much to prevent air from going underneath without a significant increase in frontal area. I think you would see cleaner airflow with belly-panning.

that said, a lot suv's i see have signifficant airdams at the bottom.. usuallt spit in a wheel dam section and some sort of semi bellypan...

any little improvement is a good think... might not show up on the fuel charts in a big way, but all bits add up

Have you done any tuft testing of the new cap? I would be curious to see what that looks like.

Looks good.

Next iteration: A lid.

how do you mean a lid?

i don't think i can do any tuft testing myself, but it's certainly something to look for in the future when i may be doing modifications that are less certain to work compared to all the other more obvious changes.
but today the higway was completely soaked, and i watched the watercloud created at the rear verry carefully. at first point it looks less large than before, and it seems like the water is kicked up, and when it reaches the height of the cap it stops. while before it used to go much higher. i also noticed the cloud seems less turbulent, it sort of keeps the same shape while before it used to be verry unstable. this is all verry promising, and just the smoother feeling you get while driving is great.

another thing i noticed with the watercloud is that it seems to start behind the rear wheel, where it strangely jumps out to the side about half a meter away from the side.

i noticed that the frontally incoming air hits all 4 tires above their centerline, wich means that the top layer (wich i suppose is more dense) gets directed over the tire and has to travel through the well. so i think that making triangular air diverters in front of the tires to lead the air to the sides of the tires will greatly help along with wheel flaps and rim caps.

Can you still use the bed cargo space?

A lid is a section of the cap that is hinged in front and allows access to the bed for bulkier items.

Your rig has the same problem mine has - carrying anything taller than the height of the tailgate is a real problem. In my case the tail gate height is 24 inches and I cannot easily gey anything bigger than that in it.

What we have is not truly a cap but a static fairing.

http://i77.photobucket.com/albums/j5...tt_vorne_1.jpg
http://i77.photobucket.com/albums/j5...t-mustang1.jpg
http://ecomodder.com/forum/attachmen...1&d=1234085358
http://i77.photobucket.com/albums/j5...ael_knight.jpg

haha good pics :D if one can aeromod a vehicle and make it look cool aswell, it can only help our cause! ill add a red beamlight to the hood, it already talks to me like nightrider when i use a gps ;)

now i understand the lid part, yeah i was thinking of making it lift-able from the rear, but my cap is too heavy for that. and making a self-baring polyester-only cap without all the wood underneath to solidify it, would at least triple the cost.
i know my cap is not ideal, theres lots of things i would have done better if i was rich and had a whole team working for me. but this is the best compromise for me.
you can still put anything in it as long as it's not higher than the tailgate, wich for me is good enough in 98% of the trips i do. we only occasionally carry larger things like tractor tires or seed bags. but the cap can be removed in 2 persons in less than 3 minutes.

I wonder what david hasselhoffs cd is.

he looks sleek enough in the picture but i think frontal area could be significantly reduced with a new haircut.

Great work, Sepp. Looking forward to a report on fuel economy.

Were you keeping detailed records before the mods?

i don't have a scangauge or anything, but when i had my rooflights i never was able to reach 700 km with one 65-70 liter tank. wich meanth i was doing 9.2 to 10 l/100 km.

after removing the rooflights i was able to reach 800 km per tank (theoretically, as i had to refill each time before the tank was nearly empty) but the amount left given by the gauge told me i could have reached 800 km.
wich meanth between 8.12 and 8.75 l/100 .

now i have only done about 150 km since i have the cap on, but by the eye i can see a difference on the gauge. as it is split in 4 quarters i always do 200km per line. and now even though only 150 of the 200 km of the third quarter was done with the cap on, i did 220 km before reaching the line. wich can give a vague estimation that now i could be around 7 to 7.5 l/100km! that would be great! lets hope reality is not to far away from that!

btw the EPA for that vehicle is 10.7 l/100 km, so i would be 33% under

ps, most of the miles i do are of the worst kind, several times a day i drive between our two farms, wich are separated by only 2 km, so the engine never gets hot. and when i take the highway (wich is at 500 m of where i live) to go get my GF, it goes up verry steeply for about 2 km, and the engine temp needle usually only starts moving up once im 2/3 rd up the hill.
and to make it worse, my dad drives it aswell and he aint no hypermiler at all

Hey, SnugTop has an aero canopy! Ironic as it may seem, its for the Hummer!!! LOL!!

http://www.snugtop.com/products/imag...e%20Dealer.jpg

Well, at least there is hope for the rest of the world if the Hummer folks have one.

Hi Sepp;
Great job! I just found this thread - wish I'd had a chance to give you some tips on handling the fiberglass. It really can be a lot easier. I'd have unrolled full-width cloth across the wood, and for polyester, really heated up the wood. Then, I'd pour a puddle of resin on the middle, and quickly squeegee it out to the edges. By using unwaxed resin, you get a tacky surface that will bond well to a coat of Gel-Coat over that. The final coat has wax mixed in to keep air off the surface and allow a full cure.
The Gel-Coat is easy to sand, polish, and patch as you go for a perfect finish. If you can't arrange to spray it on, a coat with a notched trowel, followed by a coat with a regular trowel might work a lot better than brushing it on.
Epoxy is excellent for waterproofing to eliminate swelling, provided it is a continuous coating. I often keep leftover, mixed epoxy in the freezer to use for touchups - if it is properly mixed, you just have to heat it up and wait for hardening. It does not have a sudden transition like polyester.
For truck caps in general, I keep hoping to see a side-hinged unit made of lightweight Coroplast.

Looks great :)

Rear-view cameras for cheap are available from China: DealExtreme: Driving Aids (Page 2)

Nice work! I bet you could find a rear view camera cheap online somewhere.....

haha, looks like I pressed submit after you clicked onto the page ;)

luckily that cap is being cancelled by that kayak

:p

http://www.snugtop.com/products/imag...e%20Dealer.jpg

I like that one^ Can't wait to get started on mine.

Looks like mine. I did one for my '98 Dakota. Went from 18 to 22mpg but the computer soon learned and screwed me! I took it off. Next time, a slight redesign and build from better materials.

First off welcome to the site.

Second off, your computer will learn of your aerocap the instant you start moving. It knows this because your vehicle moves easier through the air. If your mileage dropped after the fact I can assure you that it was not the computer making changes, it was other variables.

You mean you have one of these?...
Knight Rider GPS by Mio - Let K.I.T.T. give you directions!

http://images.listenernetwork.com/in...c30a1b17ad.jpg

Well, actually I have done many things to improive mpg's. Some worked, some didn't and after a few starts, none did! period.
It's OBDII
Dominant
Big
Oil

spelled backwards!

hello again, the first complete tank i did with the cap on felt rather disappointing. i calculated that my consumption was of 9.2 liters, wich is still an improvement compared to the 10 plus liters i averaged before. but obviously alot less than my early over-optimistic estimation that i was doing around 7 liters.
but! the trips i did with that tank were unusually mpg-unfriendly compared to what i do normally. verry few highway and lots of verry small trips. i even hauled a bathtub around in the back with the cap removed...
now im halfway through my second tank, and i have also decided to pump up the tires to right under the maximum of 40 psi. and there is a difference already on the gauge and on the feeling. and the fact that it's getting milder ouside is helping also.
ill report the consumption as soon as the tank is empty again.

ps, i have a question for those with a scangauge.

what is the most efficient way for me to go pick up my girlfriend?
the shortest way wich i always take is 1 km on road and 8 km on highway, and the other way without highway would be 11-12 km on road mostly limited to 50 kmh.
with keeping in mind that im driving a pick-up, i ususally cruise at 80-90 kmh on highway. and that my gears are rather short so im basically always in 5th from 40 to 130 km/h

basically is it best to cruise for 10 minutes with the engine mostly at a high rpm (2500), or to drive on smaller roads for 13-15 minutes with the engine mostly around 1300 rpm? knowing you oftenly need to slow down, turn stop etc...

since i have no scangauge i can't tell!
thank you

Sepp, I am very impressed. I recently bought a Nissan Frontier and after seeing your thread here, I am considering making my own cap. I don't have much free time to work on it, or experience, but my father has built several wood/fiberglass canoes...

Have you found any good options for the wheel covers? And what did you use to cover your grill. That looks very clean.

Keep up the good work!

Short-term MPG tests give too much scope for distorting factors (i.e. head and crosswinds, traffic, rain or snow).

A quick snap shot is of VERY limited value.

Do an A-B-A test with each leg about four tankfuls. A shorty test could be distorted by how you fill the tank.

I cannot believe an aerocap failed to improve mileage in a valid test.

Oh, one more question for you Sepp, do you notice your truck over-heating at all once you blocked up all of the grill? I am thinking of doing the same for my truck but it is a work truck that hauls trailers and loads of stone and mulch. I am worried about overheating problems, which is why I am thinking of making whatever I try out to cover the grill easy to add or remove in case the truck would be working hard on a hot day.

@ goodoak, the front grill cover was just a temporary cardboard peice cut out to fit in the opening and covered with black masking tape to make it watertight and discrete.
meanwhile my dad couldn't help ripping it off because some garagist said it was bad for the engine (i could have strangled him)
i never saw an increase in temperature, and not even the engine warming up faster (wich i hoped it actually would do, but it didn't) fact is that the engine still gets more than enough fresh air to keep cool, you don't need a direct frontal air supply. but i suggest you build something temporarely and see if your temp changes.
i have not found any acceptable method for getting wheel covers to hold on my rims yet unfortunately.

and im glad to hear you want to make a cap, im actually thinking of making a new one. i suspect that the cap i have now is too heavy and may actually increase my consumption at slow speeds below 50 km/h where its just more dead weight. and that the end-curb may be to steep downward so at speeds over 80-90 km/h the airflow detaches. im not 100% sure but i feel it happening once i go over 90 km/h.
the cap i made is just too solid, you can walk on it and i think it weighs around 60 kg (120 pounds?)

i would like to make a new one wich would be as light as possible with much thinner wooden beams, wich would not go down so low and would have plexi-glass windows. and also wich would allow the above part to be opened or even removed to haul large objects in the back.
i don't know yet with what material i will cover it, i saw that aluminium sheets are available in verry thin thicknesses and are cheaper than the thinnest metal sheets. im not planning on using fiberglass and polyester anymore, too expensive and hard to manipulate and can't be recycled. while a wood-aluminium combination is fully recyclable.

about the consumption with my current cap, the last 2200 km i averaged a verry nice 8.3 liters, wich is 2.4 liters under its EPA!

Without more immediate information, it's difficult to tell what your best option is, but it may be a wash. The 50kmh route is probably going to deliver your best fuel mileage, but you might wind up using just as much fuel by covering a greater distance. Without instant feedback on your fuel economy performance though, it's really tough to say whether one is better than the other in terms of actual fuel use.

Love the cap. I need to make one like that.