Honda Insight Under-body Smoothing Panels (custom belly pan / undertray)
 

After purchasing a used 2000 Honda Insight, several things came to mind when attempting to change the oil:

1) Before the oil could be drained, several panels had to come off.
2) The existing panels were rather flimsy, and might move easily in the wind
3) Getting the panels back on in cold weather, was shall we say, 'interesting' with cold fingers.

That made it obvious that something would be done when warm weather came in Wisconsin.

In May of 2009, 1) the motorcycle was brought out of winters hibernation to get back and forth from work, and 2) the Insight was jacked up to determine how new panels could be implemented. After accessing what hard points were available, construction was started on the mounting system.

http://ecomodder.com/forum/attachmen...1&d=1256090440

http://ecomodder.com/forum/attachmen...1&d=1256090440

Hard mounting points for the support rail were embedded into components on the car.
http://ecomodder.com/forum/attachmen...1&d=1256090440

http://ecomodder.com/forum/attachmen...1&d=1256090440

Making a curved surface, requires many smaller blocks glued together.
http://ecomodder.com/forum/attachmen...1&d=1256090440

Here you can see the blocks filed down to a smoother shape.
http://ecomodder.com/forum/attachmen...1&d=1256090440

Here's a close-up shot of the blocks.
http://ecomodder.com/forum/attachmen...1&d=1256090440

You can see the many small blocks that are added together, to make the overall shape.

http://ecomodder.com/forum/attachmen...1&d=1256090440

http://ecomodder.com/forum/attachmen...1&d=1256090440

This shot shows the panel about one foot in front of the second catalytic converter. In the foreground in an access hole for changing the oil filter.
http://ecomodder.com/forum/attachmen...1&d=1256090440

A detail shot showing the hard mount points and embedded wood blocks that act as stress relievers to the relatively soft foam.
http://ecomodder.com/forum/attachmen...1&d=1256090498

Now you can see the panel extending rear-ward towards a new hard mount point. Also, in the middle of this picture is the access hole for the oil drain. There is a fumoto oil drain valve mounted there to aid in easy oil changes.
http://ecomodder.com/forum/attachmen...1&d=1256090498

Fresh blocks of foam are being glued in this picture and extend to where the drivers side panel will be started later. The drivers panel was missing when I bought the car this spring.
http://ecomodder.com/forum/attachmen...1&d=1256090498

This shot shows the start of an inverted airfoil, covering the underside of the suspension arm.
http://ecomodder.com/forum/attachmen...1&d=1256090498

Start of the inverted wing shape on the drivers side.
http://ecomodder.com/forum/attachmen...1&d=1256090498

This shot shows just how complicated the shape is on the back side of the panel. You can imagine the hours it took to shape all of this.
http://ecomodder.com/forum/attachmen...1&d=1256090498

A close-up of the contour shape of the back side of the panel.
http://ecomodder.com/forum/attachmen...1&d=1256090498

This is the same area after smoothing out the area. This will allow the glass cloth an easier time of adhering to the complex shape. More shaping is yet be done, however. The foam needs to be very smooth before glassing.
http://ecomodder.com/forum/attachmen...1&d=1256090498

Now the back side of the panel is starting to take shape!!
http://ecomodder.com/forum/attachmen...1&d=1256090498

This area is a little thin and weak, so another layer of foam is added for strength.
http://ecomodder.com/forum/attachmen...1&d=1256090552

Here is the shape smoothed down so the glass cloth will transition the shape easily.
http://ecomodder.com/forum/attachmen...1&d=1256090552

The is the blocked-out area of the suspension airfoil.
http://ecomodder.com/forum/attachmen...1&d=1256090552

After shaping with a rasp file, here is what the shape looks like.
http://ecomodder.com/forum/attachmen...1&d=1256090552

Here's an edge view of the airfoil.
http://ecomodder.com/forum/attachmen...1&d=1256090552

Airfoil almost finished now.
http://ecomodder.com/forum/attachmen...1&d=1256090552

Panel is back on the car now, and the wheel well area being filled in. This accomplished two things:

1) Support for this portion of the panel.
2) Keep snow from being packed under the panel in this area.

The car is primary transportation in the winter.
http://ecomodder.com/forum/attachmen...1&d=1256090552

Adding yet more blocks.
http://ecomodder.com/forum/attachmen...1&d=1256090552

This area is almost filled-in now.
http://ecomodder.com/forum/attachmen...1&d=1256090552

Hey, just about done. A pair of wood blocks are used to hold the two portions of the panel together in this area.
http://ecomodder.com/forum/attachmen...1&d=1256090552

And the same thing on the front side of the wheel-well.
http://ecomodder.com/forum/attachmen...1&d=1256090619

A backside view of the almost complete panel. Notice all the hard-mount locations. This is ensure that snow does not pack behind the panel in cold weather.
http://ecomodder.com/forum/attachmen...1&d=1256090619

This shot shows the geometric layout of the panel's backside.
http://ecomodder.com/forum/attachmen...1&d=1256090619

You can see the embedded wood blocks, to allow attaching to the car.
http://ecomodder.com/forum/attachmen...1&d=1256090619

Here's the panel flipped over and just about smoothed out. If this were a car body panel, the entire surface would be glazed, sanded, primed, and painted. This process would take about one more month to get smooth for exterior body panels.

The project has taken six weeks at this point.
http://ecomodder.com/forum/attachmen...1&d=1256090619

A detail shot of the oil filter access panel, and oil drain hole.
http://ecomodder.com/forum/attachmen...1&d=1256090619

And the recently fiberglassed wheel well supports.
http://ecomodder.com/forum/attachmen...1&d=1256090619

And the front side.
http://ecomodder.com/forum/attachmen...1&d=1256090619

This shot shows the tight fit of the panel on the car body.
http://ecomodder.com/forum/attachmen...1&d=1256090619

Jim.

:thumbup:Fannnntastic, it must have taken a zillion man hours.
I can't wait for the mpg testing!

panels
 

Your attention to detail is what will make or break the performance of a bellypan.I'm very impressed! Did you add the Dzus fastener weld plates? or is that something Honda already used? Those 1/4-turn fasteners are a great way to go.Thanks for sharing the thread.

It took all summer to make the engine and drivers side panels, which would be about 2-1/2 months.

As for MPG, I seem to be getting about 7 mpg more than before. Average is about 81 with 60F temps, and this is over a full tank of gas.

Next spring, I would like to perform Cd generating coast down numbers using a hand-held GPS device that sets on the dash.

Jim.

aerohead,

Thanks for input. I have read many of your various threads on 'aero' issues, and find many of your comments very interesting. In fact, besides reading about the aerocivic, I find the aerodynamics area the most interesting part of EcoModder.

As for the fasteners, I used various fasteners in different areas. Since the panels are not likely to be removed very often, most are fastened with course wall-board screws. These fasteners are either screwed into the aluminum under body rails or into custom made wood substructures that are epoxied in place. A few of the fasteners are machine screws.

Jim.

Thanks for letting us see what you did over the summer! It's making the gears in my head turn for building a hybrid foam/fibreglass/metal tray in sections for my car.


I'm curious, though, about some of the unmentioned details of your build.

Did you glass over the top/inside surface of your tray?
Did you coat or prep the rest of your wood you mounted on the car to secure the tray?

I know the foam used would be impervious to water/slush/snow, but all the wood used, is another story entirely.

This is really nice work - thank you for posting this. Exciting!

just cross posting this picassa link from insightcentral

Picasa Web Albums - jsmosher - Air-Smoothing... :)

I nominate this for the Mod of the Month!

(I installed CoolIris so I could use it on the Picassa page...)

Hi Christopher,

Both the top and bottom side of the foam board is glassed over. This is known as typical 'composite construction'. The foam board by itself is not very strong, but very light. A layer of glass cloth impregnated with resin is itself is not very good in compression, but very good in tension.

When the two are added together however, now you have a very light, yet strong structure. Plywood is another composite structure of sorts. It utilizes various layers of grained wood to make a structure that is stronger than the base wood would be without the cross-grain structure.

All of the wood supports mounted to the car have been epoxied to keep the water out. The only weak area is were the wood screws hold the panels onto the car. Water can seep into those areas. Only time will tell how this holds up.

I do have a motorcycle fairing with 115,000 miles that is constructed in a similar manner and still looks good, but it is not mounted underneath a car body either. However, the fairing still gets rained on just like the car, since I typically ride it rain or shine when it's warmer, such as this summer when working on the smoothing panels.

Jim.

Hi Neil,

I read your entire thread, and learned a few more techniques that I can look into next year, when the weather gets warmer.

I thought the foam under the hood seam to keep air out was a nice touch.

Keep up the good work, and keep posting your progress as it makes for interesting reading.

Jim.

Guess you'll find out how it'll fair until you run with it on 'til spring is back again. :)

I noticed too, with silverinsight2's mention of your Picasa web folder, there's more pictures there than were shown off here, showing yet additional fairings. LOTS of work went into this, and if you are getting your additional 7mpg, at least you've something tangible to show for it.

I'll have to look at my underbody pictures I took the summer before, and plot and scheme how I'll attach similar fairings. Fairings and living in the snow belt have kept a few of us a bit wary of going too aggressive with smoothing out down below -- because of concerns about snow and ice packing, or how it could pack more sand/salt crud used to melt it in on the underside where we'd prefer it not to be.

Please be sure to update how it performs after winter's through.

Hi Christopher,

I plan on adding more pictures of the other panels to this thread, so those who are interested, do not have to look at the other posting on Google.

You are right, in that the snow, and it's affect on the panels is a concern. More specifically, those hard, crusty, pieces of hard ice that drop off the cars could *really* cause a problem with these panels. The panels are plenty strong for high air speeds, but no match for a carefully placed 'snow crusty'.

I also have to make a fender-well snow guard for the rear wheels, to keep snow from packing in that area, similar to the front. With the weather getting colder, it may be a bit tough, but we will give it a try.

Jim.

--- Drivers Side Smoothing Panel ---

Wood strips are fiberglassed and attached to the underside of the car.
http://ecomodder.com/forum/attachmen...1&d=1256520408

Foam blocks are glued to the wood sub-structure.
http://ecomodder.com/forum/attachmen...1&d=1256520408

More blocks are glued in between the edges of the wood pieces.
http://ecomodder.com/forum/attachmen...1&d=1256520408

The entire shape is almost roughed in.
http://ecomodder.com/forum/attachmen...1&d=1256520408

Now that the structure is strong enough to support it's own weight, it is taken off the car.
http://ecomodder.com/forum/attachmen...1&d=1256520408

The rough edges of the blocks are tapered and smoothed in preparation of adding glass cloth.
http://ecomodder.com/forum/attachmen...1&d=1256520408

Back on the 'smooth' side of the panel, more foam is added to fill-in a low spot.
http://ecomodder.com/forum/attachmen...1&d=1256520408

After much blending of the foam, glass is added and wetted out with resin.
http://ecomodder.com/forum/attachmen...1&d=1256520408

Now the wood, foam, and glass can be seen in this picture.
http://ecomodder.com/forum/attachmen...1&d=1256520408

This is the 'smooth' side of the panel after glassing and adding a small amount of glazing.
http://ecomodder.com/forum/attachmen...1&d=1256520408

And another view of the smooth side of the panel.
http://ecomodder.com/forum/attachmen...1&d=1256520424

The panel mounted on the car.
http://ecomodder.com/forum/attachmen...1&d=1256520424

Jim.

Holy crap. Are you going to bring this to the green grand prix next year? This could give this year's winners a run for their money. Going to boat tail this? You're pretty much going all out already....

Very nice work. Kudos.

Hi Wonderboy,

Where is the green grand prix?

I was at Hybrid Fest in Madison last summer. Of course the car was in the garage, and I rode the motorcycle, which currently barely gets the same mileage as the Insight.

When the weather gets warm next summer, I doubt the motorcycles 79 mpg best will be able to keep up with the car.

I think the Grand Prix guys can kick the snot out of my 'normal' driving style, since I rarely pulse and glide. However, 43 mph seems to be my favorite speed for driving to work on old country roads.:)

As for boat-tailing; yes I can see the day coming when I would try something like that! It goes without saying that six months would be reserved for sanding/glazing/priming/painting the fiberglass to get that 'smooth' finish.

Jim.

Just found this thread. WOW. Impressive work, Jim!

EDIT: the GGP is in Watkins Glen, NY.

Thanks Metro!!

There are a few more pictures to post soon.

Jim.

very impressive indeed. what did you use the GREAT STUFF FOAM for?

What are you using to glue the foam pieces of the puzzle together?

Hi k.civic,

The Great Stuff foam has a limited use for my foam/fiberglass projects, since it's density is too low, and it can only be used to fill shallow areas, since it needs air contact to setup properly. The sunlight also causes it to change shape for what seems like several weeks as it stabilizes.

The foam was used to keep wheel well water out of the outside body panels on the rear wheel area. The Insight has the 'flare' that helps the air flow around the rear tire, and the plastic panel that provides this shape is hollow, and likes to collect water and debris.

I first put some large foam blocks in that area, to take up most of the volume, then filled in the remainder using the Great Stuff foam.

Jim.

Hi Metro,

My favorite glue for holding things together is ordinary Elmers Wood Glue. And the favorite thing to hold blocks together until the glue dries, are long plaster board screws that you get from the hardware store.

For tiny pieces of foam glued together, I use sewing pins to hold things.

When using Elmers Wood Glue, one thing to consider is when the glue gets wet, it starts to reverse the gluing process, and the glue gets soft again. Because of this, the foam needs to be coated with something to keep water away from the glue, like epoxy resin or latex paint. Anything that will not attack the foam and also seals the glued surface will work.

Jim.

On some ways, the rear panels by the gas tank were harder to make than the front engine panel. This picture shows a shot from the rear of the car looking forward at several mounting points that were added.
http://ecomodder.com/forum/attachmen...1&d=1257735883

Several more mounting points are shown here. The extreme left of the picture shows the area where foam blocks were added to flare in front of the rear tire, and where Great Stuff Foam was used to fill in the small gaps.

You can also see how much the thickness of the driver side panel varies. The panel wants to be as thick as possible for high bending strength, but not protrude down into the air stream under the car.
http://ecomodder.com/forum/attachmen...1&d=1257735847


Here's another picture of the wood blocks used to stabilize the panel under the car.
http://ecomodder.com/forum/attachmen...1&d=1257735847

This mount was added after the panel was almost complete in shape. The author just wanted to have slightly better mounting support in this area.
http://ecomodder.com/forum/attachmen...1&d=1257735847

This pictures shows both panels in various states of completion.
http://ecomodder.com/forum/attachmen...1&d=1257735847

Here weights are used to hold the layers of foam tightly together until the glue dries.
http://ecomodder.com/forum/attachmen...1&d=1257735847

Now you can see the extra thickness from gluing large foam pieces to increase the thickness in various areas.
http://ecomodder.com/forum/attachmen...1&d=1257735847

Various instruments are used to trim the foam thickness where needed.
http://ecomodder.com/forum/attachmen...1&d=1257735847

About two weeks later, and after adding several coats of light-weight spackling, you get a glimpse of just how much sanding dust one can make when smoothing things out.
http://ecomodder.com/forum/attachmen...1&d=1257735847

Whoops!! The sanding went a little too far towards the left and right most areas of this picture!! On the right side, more spackling is added, and on the left, another piece of foam.
http://ecomodder.com/forum/attachmen...1&d=1257735880

It's hard to tell in this photo, but the entire back side of the panel has been painted with Latex based paint. The panel has already seen life on the car, and through several very rainy days.
http://ecomodder.com/forum/attachmen...1&d=1257735880

Here is the reverse side after fiber-glassing.
http://ecomodder.com/forum/attachmen...1&d=1257735880

Both rear panels side by side. You can barely make out the layer of wood in the thinnest area of the panel, which is about 1/4 inch thick. The wood is heavier than foam, but gives needed support in this area.
http://ecomodder.com/forum/attachmen...1&d=1257735880

You can clearly see a portion of the accumulated road dirt in this shot. So far the panel has seen several weeks of rainy fall weather.
http://ecomodder.com/forum/attachmen...1&d=1257735880

Here is a shot of the panels mounted on the car.
http://ecomodder.com/forum/attachmen...1&d=1257735880

Another shot of the gas tank panels. You can see the cutouts for the exhaust pipe and rear brake cables. There is about a 1.0 inch gap on either side of the tail pipe in this area. There have been no signs of foam overheating is this area. Foam starts to degrade at about 250F or so, and it looks great in this area, so the tail pipe runs cooler than that here.

Of course my driving may have something to do with this, as my typical speed on the way to work is usually 45mph or so.
http://ecomodder.com/forum/attachmen...1&d=1257738814

http://ecomodder.com/forum/attachmen...1&d=1257738814

Jim.

Thanks for the glue tips. I continue to be mightily impressed.

Any plans to add your car to the garage? (If only so it appears under your username to give all your posts some context.)

Hi Metro,

Actually, the *glue tips* regarding the use of Elmers Glue can go even farther, if done correctly. Take a look at the motorcycle fairing below...

http://ecomodder.com/forum/attachmen...1&d=1257908565

Now take a guess on what type of *epoxy* is used to hold the glass to the foam core. Polyester resin? No. How about more expensive Epoxy resin? Sorry. Try again.

How about Elmers Glue!! Yes!!

All the glass added to this fairing, both inside and out was all added by soaking the cloth with Elmers Wood Glue. Obviously, it could not be vacuum bagged when the glue is setting up, but hey, it's a whole lot cheaper than other options.

As for longevity, this fairing has been on this same motorcycle for the last 15 years, and besides some scratches here and there, looks really good after 115,000 miles, through rain and shine.

Metro, you might want to try this approach on your boat tail project. The only caution is to make sure that all water can not come in contact with the glue, and this is easily done by *encapsulating* the glue with glazing putty to smooth out the rough edges, then later, spraying with primer and finally painting and clear coating. Sounds easy, doesn't it?

I hope this encourages you or others to give it a try.

P.S. I used West System epoxy resin exclusively on the Honda Insight under-body panels, since there is a higher risk of rocks and other debris *chipping* the outer surface of the structure. This could easily put the Elmers glue at risk, since the panels can not be viewed and monitored easily due to their location.

Jim.

Hmmm, awesome, will you do my under body too?

LOL.

If only it were that easy!!.

It's funny too, cause if you add up the cost of the supplies, like the foam board, and glue to hold the foam, it costs less than $100 for all the panels.

The big ticket items are the cloth at about $50 and the resin at ouch, $100.

If someone wanted to be *really* thrifty, they could...

1) Buy foam board
2) Purchase loose weave nylon fabric, similar to a 'breathable' wind breaker
3) Get about one gallon of Elmer's Wood Glue
4) Pickup some small pieces of wood, and attach to underbody at strategic locations
5) Using nothing more than a hacksaw blade, 1/2 round 1" wide rasp file, 60 grit sand paper glued to a foam block, and start cutting out foam pieces and...
6) Glue together
7) Shape and smooth, then *glue* the nylon fabric on the outside of the foam board shape

You mentioned somewhere that you've insulated your catalytic converter to keep underhood temps down. What kind of insulation did you use?

The stamped aluminium heat shields are falling off my cat. I want to upgrade them to something with more insulation than stock, because I plan to enclose the engine bay. However, unlike Lil' Red, my Zombie will be climbing hills at 75mph in 3rd gear.

Thanks for the additional glue tips!

Did you also paint that motorbike fairing yourself? It's pretty darned shiny. (Having seen your attention to detail in the belly pan, I wouldn't be surprised.)

That really looks nice and healthy, keep up the good work, what are the MPG numbers?

And the question on everyones mind is ........

When you finish this thing, are you going to make a mold of it so you can sell it ???

If I had an Insight, I would pay good money for a 'pan like you have produced.

Very, very professional.
Well done !

Hi Robert,

The cat is surrounded with fiber glass batting. The same stuff that is used for thermal insulation in houses. Obviously, there is no paper backing, just the glass, which has a melt point of about 2000°F. Steel melts around 2500°F or so and starts to glow dull red about 1500°F or so.

So the glass *should* be able to take the heat from the cat.

Jim.

Hi Metro,

I painted the three colors in fast drying lacquer, so the bugs would not have time to stick to the fresh paint.

My brother shot the two-part clear coat in his garage, and guess what... there were flys stuck to it after the paint dried. LOL.

Jim.

Hi discovery,

My best MPG from the motorcycle is 80 mpg at 45 mph. I've been eco-milling the bike since the spring of 2007.

Typical mileage is from 70 to 75 mpg or so. I ride rain or shine when the weather is above 40°F or so, especially when working on the Insight.

Hi Cd,

I didn't have plans to make any parts that big and the custom mounts to the car could make it harder to sell. Especially those on the back by the gas tank area.

However, I can certainly see the day coming when I would want to make a boat tail for the car.

Jim.

Here's encouragement for those thinking of under-body panels, and mixing this up with winter driving. :)

Several weeks back we got about 3 inches of soft, powdery snow at night. Normally this would not be a problem to drive through, but the winds were gusting to 30 mph or so...

On the way home it was already dark, and I turned down an old country road... and suddenly realized the drifted snow is at least six inches deep and the Insight only has 5 inches of clearance, and stock tires. :(

In the really deep stuff, the car felt like it 'floated' over the snow and did not seem to 'grab' the snow like the old Cavalier did in the same scenario.

Fortunately, the snow was not hard packed, or the situation might have been different.

Knock on wood, but so far, so good.

Jim.

I've done the same thing in my VX with the under pan. I actually lifted the wheels off the ground though.

Your Insight has 5" of ground clearance while at rest, but remember that there are a few inches of upward and downward travel available as well. Sounds like you were still catching traction with the wheels on the ground and the snow was lifting some bulk of the car of the suspension.
Been there with the hard pack and ended up ripping off half my under pan. good thing I could jsut throw a new sheet of Coroplast back on when I got home. :thumbup:

http://www.insightcentral.net/_images/sidedims.jpg

5.9 inches;)

I've been watching your fuel log, and wondering how you managed to prevent your gas mileage from falling with the onset of winter. Summer tires in the winter, eh? You're crazy. ;)

Btw, the Blizzak MZ-03 will hurt your gas mileage, but they're competent on snow and ice, unlike the Potenza RE92's.

Hi Robert,

Snow tires haven't been on any of my cars for about 25 years or so.

Sure there might be a few days when they could be useful, but probably less than 1% of time. If the weather is really bad, then the 55 mph highway is pressed into service, since they are typically better maintained than the old back roads.

As for keeping the gas consumption low, my travel speed tends to slow down this time of year for two reasons:

1) The roads tend to be more slippery
2) They buckle up so bad in Wisconsin, I really don't want to beat up the car's suspension over those nasty bumps.

That tends to keep the gas mileage higher. :)

Jim.