Civic hatchback aerodynamics

[basjoos]

So far, I have installed underbody panels, grill blocks, read wheelwell skirts, smooth hubcaps, and caulked all of the seams on the front and sides of the cars. After the caulk dried I used a razor to cut a line on those seams (doors, hoods, gas cap cover) that I need to open.

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20civic/Civic5.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20civic/Civic6.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20civic/Civic4.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20civic/Civic2.jpg

[krousdb]

Dood. you are my hero! Me next! Well maybe not the caulk.

[molecule]

ballsy
what motor you got and whats the mileage gains like

[SVOboy]

JDM D15B and CX tranny.

He's not had it on for a full tank yet either!

[molecule]

is there a reason you didn't cover the whole rear well...?
i guess you probably couldn't get the tire off if you needed to...
hmm

i'm been trying to devise a way...maybe a clip system...
where you would have to lay down and reach way up to install/remove them...

[Bunger]

Well maybe not the caulk.

Maybe if you used clear caulk, and used a piece of ice to smooth it into the cracks, the outcome would be a little cleaner looking.

All these caulk threads are reminding me of the "Caulk" skit that SNL did a little while back. I'm sure you can imagine the premise.

[MetroMPG]

nice, basjoos.

my car is going backward, aerodynamically.

my cardboard grille block that's been on since november is delaminated, the duct tape is in tatters and it's literally about to fall off on the road.

my aborted attempt at "scientifically" evaluating the belly pan hasn't been reproduced yet. and i don't want to put on the permanent version and miss the chance to know exactly what it contributes.

and my wheel skirts are off - though i did borrow the heat gun i'm planning to use to form the 90 degree lip in the plastic to mate to the wheel arch lip.

so why am i futzing around in the forum instead of making stuff...

[MetroMPG]

ps - if ever there was a candidate for a boat tail (i.e. someone unafraid of altering the looks of his car), it's you. you're going to go far!

(on less fuel, of course)

[Matt Timion]

i'm been trying to devise a way...maybe a clip system...
where you would have to lay down and reach way up to install/remove them...

The other day while waking up (you know those half dream / half awake moments?) I actually figured out how to do this.

I'm currently finishing my basement and I picked up a "pocket hole" kit for making strong, simple joints with wood. I used it to build a bookcase, and I'm also going to use it for a few other things.

Essentially the plan is to make a wood positive, or maybe a wood and bondo positive. I'll then make a mold with plaster of paris and THEN i'll make another positive with fiberglass. I'll smooth it out (with some primer and maybe a little bondo too. In 3 or 5 locations on the back of the fiberglass wheel skirt I'm going to put a giant gob of plastic epoxy. When it dries I will use the pocket hole system and drill a few holes that will be angled.

At this point we can drill a few holes in the car using the small half inch "lip" in the wheel well and maybe put those little plastic female screw receivers (usually used for mudflaps) into these holes.

Anyway, it's a lot process, but it should be hella fun when it's done.

[Bunger]

I've used Dzus fasteners in the past for hoods, bumpers, front ends, etc... should be great for what you need.

http://www.kenlowe.com.au/body_hardware.htm

Some of the pictures there will give you an idea of what I'm talking about, I'll see if I can find some better ones.

[Bunger]

http://www.zealautowerks.com/images/dzusanim.gif

They have self sprung versions that are perfect for fibgerglass too, use these and you'll be getting much props from the racer crowd. =)

[Matt Timion]

http://www.zealautowerks.com/images/dzusanim.gif

They have self sprung versions that are perfect for fibgerglass too, use these and you'll be getting much props from the racer crowd. =)

I'm trying to understand exactly how this works and my mind can't grasp it. What does the spring do, and how is it held in place? Will it require me to weld the plate to the body?

[Bunger]

I'm trying to understand exactly how this works and my mind can't grasp it. What does the spring do, and how is it held in place? Will it require me to weld the plate to the body?

You don't have to weld the plate to the body, but most do. You could bolt it on if you wanted to remove it later.

Basically, the button gets riveted to the fiberglass (or whatever) wheel cover. then you attach the backing plate to the car where needed. When you tighten the button, it becomes flush with the car. Very clean and simple. Depending on the strength of your wheel cover, I think 3-4 fasteners would do per side.

[molecule]

excellent

[tomauto]

I can't see the pics...

[basjoos]

Just got back from a trip to Savannah, GA. This is the first long distance trip I have made in my Civic Hatchback since I installed the aero mods. Even while cruising at 75mph on the interstate, I was getting 62MPG. In the past, I would be getting around 44MPG while travelling at these speeds. Since I couldn't do a lot in the way of driving technique (other than a small amount of drafting) to improve mileage on a flat coastal plains interstate, this mileage improvement is purely the result of the aero mods I installed. Its interesting that although everybody is *****ing and moaning about the higher gas prices, this has yet to change their driving behavior and the traffic on I-95 was going just as fast as it always does.

[SVOboy]

Damn, 62 mpg at 75 mph, that's ridonkulous.

[Matt Timion]

Damn, 62 mpg at 75 mph, that's ridonkulous.

Agreed. I'm going to start planning some aero mods as soon as the engine is swapped, which should be VERY soon now.

[thisisntjared]

wow! that is crazy! i wish the pics were still working....

[SVOboy]

Next time they're up I'll have to duplicate host them.

[molecule]

high priority thread...
it should almost be a sticky...
even without pics
i could see this rounding up over 50% of available mpg gains on my car
i found some good stuff in my garage too
ICING
and a sheet of thin/clear plexi

[Compaq888]

Damn, 62 mpg at 75 mph, that's ridonkulous.

DAMN!! :JAWDROP:

[The Toecutter]

you should try to calculate your Cd using the coast down method, after figuring our your rolling resistance and such. I'd be interested in knowing.

I suspect you got your Cd down to around .21-.23 to get those MPG figures.

I'm also trying to figure out a way to mimic the effects of the caulking without a car looking like a rolling sicence project. I'm thinking of using bondo to do it, only smoothing it out. A razor could cut those seems just as well. Done right, you could no doubt paint over such a smooth surface and it would look real slick, as if it came like that from the factory...

[Matt Timion]

you should try to calculate your Cd using the coast down method, after figuring our your rolling resistance and such. I'd be interested in knowing.

I suspect you got your Cd down to around .21-.23 to get those MPG figures.

I'm also trying to figure out a way to mimic the effects of the caulking without a car looking like a rolling sicence project. I'm thinking of using bondo to do it, only smoothing it out. A razor could cut those seems just as well. Done right, you could no doubt paint over such a smooth surface and it would look real slick, as if it came like that from the factory...

I've been wanting to do the same thing. Perhaps it's also possible to sand down the caulk once it has dried.

[basjoos]

I'm not familiar with the coast down method for Cd calculation, how do you do it?

[MetroMPG]

I'm not familiar with the coast down method for Cd calculation, how do you do it?

there's a technique described in the last post in this thread:
http://www.gassavers.org/forum_topic/weight_reduction.html

i haven't tried it. can't say for sure how well it works.

basjoos - again i have to say i'm impressed with the numbers you've achieved. 62 @ 75 is astonishing.

to compare...from another thread...

a simple scangauge trial i did yesterday - MPG at increasing speed intervals, flat road, no wind, warm (60 ish), cruise control, top gear:

69 mpg (US) @ 65 km/h (40.4 mph)
62 mpg (US) @ 75 km/h (46.6 mph)
55 mpg (US) @ 85 km/h (52.8 mph)

i could only get 62 mpg when going nearly 30 mph slower!

sure, there's probably a temperature difference between your recent driving conditions and my observations, but wow! i think i'd be lucky to get 62 mpg in the low 50 mph range when it actually gets hot here!

[tomauto]

I just dont see how more heat could help mpg.

Also, I have a question about the thermostat modication (170 to 192 degree mod) Where does all the mpg improvement come from?

From what I can see, the only way you are gaining anything is from the electric fan not being used as much but crap, why wouldn't you just have the alternator turn on while your coasting?

I totally dont see a point to the warm air intake. Maybe it is because I live further south. Maybe I am wrong, but doesn't heat hinder any performance? (speed or economy for that matter)

[SVOboy]

I just dont see how more heat could help mpg.

Hot air = less dense = less gas = more throttle opening = same gas but less friction = less gas overall.

Also, I have a question about the thermostat modication (170 to 192 degree mod) Where does all the mpg improvement come from?

Warmer engines are more efficient. Plus honda ecus pull 3% fuel when you hit 195 on ECTs compared to 180.

I totally dont see a point to the warm air intake. Maybe it is because I live further south. Maybe I am wrong, but doesn't heat hinder any performance? (speed or economy for that matter)

It hinders speed, but not economy. OBD2 might be different than obd0/obd1 hondas, but Rick (rh77) saw good increases with a WAI on his obd2 integra.

[MetroMPG]

I just dont see how more heat could help mpg.

other warm ambient benefits:

- less time in open loop (less time spent warming up)
- less tire rolling resistance
- reduced aero drag (less dense air)
- reduced losses to lubricants which are more viscous when cold (bearings, engine oil, transaxle fluid, etc)
- higher tire pressure (if you last filled it when cooler)
- and more i can't rhyme off the top of my head at the moment.

[basjoos]

That is the one nice thing about southern summers. Although they may not be the most comfortable for the driver, those hot and humid conditions give the best FE. When I was getting that 62mpg@75mph, the ambient temp was around 85F with high RH, since a stalled warm front was sitting over the area.

[MetroMPG]

perfect conditions. that's awesome.

i love reading these posts. they inspire me to continue chipping away at my car's aero issues.

i pulled a hubcap off the car tonight and brought it inside to mull over how best to streamline it (cover it fully or just cover the holes). and i worked on my permanent set of side skirts this afternoon as well.

what's up with photobucket? how come your pics disappeared?

[molecule]

maybe thats why we are burning a hole in the ozone layer
warming up earth permanantly to save fuel
its all intentional...of course...

[krousdb]

No time to work on my wheel skirts. Im swamped at work! WHo knows when I will get that done.

[basjoos]

I don't know why the photos stopped appearing, but I'll post then again below.

http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/Civic6.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/Civic5.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/Civic4.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/civic3.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/Civic2.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/Civic1.jpg

[basjoos]

The aero mods resulted in no noticable change at low speeds (below 35mph), but significant changes above 60mph. The increase in drag that I normally start to notice as I get above 65mph is greatly reduced and when I let out the clutch and coast, the speed takes much longer to come down than it used to. The decrease in drag has given me the effect of a horsepower boost at highway speeds and I can now pull hills in 5th at 65mph that I used to have to shift down to 4th to maintain speed on. Wind noise is greatly reduced and road noise is somewhat reduced. All in all, it was a great return on about $50 in parts and most of a day's worth of work on the car. It resulted in an mpg boost at interstate speeds from 44mpg to 62mpg and the mpg's for local driving went from the 54mpg typical for this time of year up into the upper 60's (hopefully into the 70's with some more tweaking and warmer weather). If the car companies were serious about improving mileage, you think they could do this treatment to the new cars they sell.

[tomauto]

I just can't wait to start my own undertray. This seems like almost an obvious thing to do to vehicles. The general public just doesn't realize that it can hurt economy of a vehicle. Maybe it is because they can't see it normally.

How many mounting points did you have on the undertray?

[basjoos]

On the Civic hatch, the exhaust runs down the center tunnel and then cuts over to the right side of the car by the rear wheel. I ran Coroplast down the left side from under the front bumper to the rear of the car, spanning from the the plastic curb at the side of the vehicle (where the lift points are) to the frame at the edge of the center tunnel. On the right side, the Coroplast ran from under the front bumper to just ahead of where the exhaust pipe curves to the right side of the vehicle. Then I spanned the tunnel with roof flashing. I drilled and tapped for 8-32 screws (used screw and fender washer) about every 14" or wherever I could find a suitable attachment point if the frame wasn't available over the the entire span. I ran white duct tape over the seams and screw heads and ran metal foil tape over the seams by the roof flashing. The hardest part was bridging the area under the gas tank, since I obviously couldn't drill into any of the metal there and the exhaust ran through the linkages of the right rear wheel which limited where I could use Coroplast over there. In the engine compartment there is a fairly large opening on either side opening into the front wheel well where the drive shafts attach to the front wheels, so I used these for the radiator air exhausts. Since I took these pics, I've had to open up the grill block some more, so I now have a single center 4" x 4" opening and the smaller opening on the right side. The taped-over opening is for the AC radiator and I'll open it if I need it when it gets hot enough to require use of the AC. Once I determine how much radiator opening I need, I'll replace this grill block with one that I can manually adjust the openings of from inside the car. Look at Krousdb's undertray installation on the Del Sol Aerodynamics thread for additional pointers as I used his installation as a referance when installing my own underbody panels.

[basjoos]

Parts list:
(2) 4'x8' sheets of 4mm thick corrugated plastic (Coroplast)
(1) 20"x 10' roll of aluminum roof flashing
(1) box of 8-32x 3/4" panhead screws
(1) box 3/4" fender washers
(1) roll of white duct tape
(1) roll of heat resistant foil tape
(4) 14' pizza pans (for flat hub caps)
(2) tubes of caulk

Tools required:
Enough jack stands or blocks to suspend your car high enough to work under with all 4 wheels removed (be careful!).
Cordless drill
Drill and tap for 8-32 threads
Box cutter for cutting Coroplast
Tin snips for cutting flashing
Screwdrivers, etc.

[molecule]

my dude was the first to ever say anything about plugging up the front of my car...
i passed it off...i should have listened...

[tomauto]

My Dude

?????

[Compaq888]

damn, the pics are just too crazy. I've been meanining to block off my fog light area just don't have any time or money now.

[thisisntjared]

My Dude

?????
uh yea-->????? also....

[tomauto]

Are you talking about a friend?

[fredvx]

Where do find the corrogated plastic?

[Silveredwings]

Damn, 62 mpg at 75 mph, that's ridonkulous.

As my son would say, "that's Hunormous!"

[basjoos]

For corrugated plastic, contact your local plastics supply house, as they usually have the best prices. Failing that, contact a local sign making company and ask if they can sell you whole sheets of corrugated plastic, but they will usually charge a lot more for the plastic than the supply house.

[blacktone]

I want to see this real bad but the pictures went down!

[Matt Timion]

I want to see this real bad but the pictures went down!

Just fixed a few of them :)

[Mighty Mira]

Man, that's cool as hell!

I'd love to know the difference the caulking makes. Another possibility would be to use aluminum sheeting over the hot bits (exhaust) in the undertray.

Pizza trays rule.

[Matt Timion]

Man, that's cool as hell!

I'd love to know the difference the caulking makes. Another possibility would be to use aluminum sheeting over the hot bits (exhaust) in the undertray.

Pizza trays rule.

I think I'm going to do the pizza tray think sometime soon... unless I can find smooth hubcaps somewhere for 13 inch wheels.

[basjoos]

On Sunday I discovered another advantage of having complete underbody panelling. I was driving through Asheville, NC just after a Thunderstorm had dumped a bunch of rain on the road. I didn't see the deep pool of water on the road ahead and hit it at 55MPH. Got through it after about 3 seconds of zero visibility through the windshield due to flying water, but with only a 4" by 4" opening in the grill and the underbody panels, very little of that water was able to get into my engine compartment and try to flood the engine.

[basjoos]

I added an extension to my rear wheel skirt to extend the skirt down to the bottom of the car. The extension is a piece of coroplast that fits on over the existing rear sheep skirt. It is held on with velcro on top, magnetic strips along the parts that overlap the metal body of the car and with two screws at the bottom. There is a piece of aluminum bar incorporated into the bottom that is bent to provide tire clearance at the bottom. Also added a coroplast side skirt between the wheels on both sides and wheel spoilers on all 4 wheels. The spoilers were made from a piece of aluminum angle with a coroplast extension added to it. I initially made the side skirts and spoilers on the long side, noted where they dragged as I negotiated my usual roads, and then trimmed them down to where they now rarely drag on the road. Its too early to tell what effect these mods are having on my mileage other than the car coasts a bit better than it did before. The main effect I have noticed is that there is a lot less dust on my rear window after driving on gravel roads than before.

http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/CivicC.jpg
Front wheel spoiler
http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/CivicCb.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/70MPG%20Honda%20civic/CivicCa.jpg

[krousdb]

Radical! Doesn't look too dorky either. I will be doing the wheel spoilers. Yours look just like what is on my Prius. Such a simple mod to do. I dont know why I havent done that yet.

Well actuallty I do. I need to pass inspection first. Then I will worry about mods. BTW, my 72 MPG trip to work today had no belly pan. MIght be able to squeeze out a few more mpgs once I get the aero mods back on.

[Mighty Mira]

Cool deflectors! Your car is an inspiration.

[The Toecutter]

You're doing what the auto industry claims to be impossible. I salute you.

I can't wait for you to experiment with this car as much as you can. Then when you ever get a newer car, you can do these same mods, only make them look professional and not like a rolling science project. Imagine shoehorning a diesel in there, and getting the same or better performance, but 80-100 mpg without codfishing and without gentle driving.

[zpiloto]

Nice job. Something to think about, when I did my side skirts I flaired the back end out about 3" with a spacer which negates the need for the rear deflector. Course your's look better than mine. Like the black paint I'll put that on my list.

[krousdb]

Can someone explain the benefits of the skirt that runs between the wheelwells?

[Mighty Mira]

Can someone explain the benefits of the skirt that runs between the wheelwells?
If the wind is nearly parallel to the path of the car (or dead calm), then the air only gets moved out of the way once, out of the way of the first wheel. Now that I understand the effects of crosswinds, I am reluctant to try side skirts, because they will slow you down with a crosswind.

[ZugyNA]

xx

[ZugyNA]

That is the one nice thing about southern summers. Although they may not be the most comfortable for the driver, those hot and humid conditions give the best FE. When I was getting that 62mpg@75mph, the ambient temp was around 85F with high RH, since a stalled warm front was sitting over the area.


If you are interested in the effects of ambient temp, altitude, and humidity on HP:

http://wahiduddin.net/calc/calc_hp_dp.htm

[basjoos]

The side skirts are suppose to keep the air flow running smooth and parallel under the car and reduce the amount of turbulence toward the back of the vehicle. I haven't run into any noticable crosswinds yet, but haven't noticed any changes in the car's behavior to the bow waves coming off passing semi's. The next step in the project are front wheel well skirts.

[Mighty Mira]

The side skirts are suppose to keep the air flow running smooth and parallel under the car and reduce the amount of turbulence toward the back of the vehicle. I haven't run into any noticable crosswinds yet, but haven't noticed any changes in the car's behavior to the bow waves coming off passing semi's. The next step in the project are front wheel well skirts.
I am certainly looking forward to that attempt. Your car is an inspiration to all of us.

[MetroMPG]

Agreed - I love your take no prisoners approach here, Basjoos.

Now, those front wheel skirts... can you say whether you're going to attempt the full meal deal, or some variation on gap-fillers between the bodywork and tires? And if it's the full meal deal, what approach to permit clearance for steering?

[basjoos]

I plan to do a full cover using 4 low-clearance conveyer rollers (1/2" x 6") spaced so they only contact the edge of the tire and push the cover outward during low speed turns. It will remain closed during high speed lane changes, etc. It will be hinged at the top with a piano hinge and with springs at the bottom to hold it shut when the tires aren't pushing it open. I hope to fabricate it from a steel sheet, but if my metal skills aren't up to the challenge, I'll make the cover from a framework of aluminum bar stock covered with coroplast.

[mrlegoman]

Pics are not working. Can you post them again?

[basjoos]

<IMG style="; WIDTH: expression(this.width > 800 ? 800: true); max-width: 800px" alt="" src="http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/Civic7.jpg" border=0>

<IMG style="; WIDTH: expression(this.width > 800 ? 800: true); max-width: 800px" alt="" src="http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicCS.jpg" border=0>

<IMG style="; WIDTH: expression(this.width > 800 ? 800: true); max-width: 800px" alt="" src="http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicCbS.jpg" border=0>

<IMG style="; WIDTH: expression(this.width > 800 ? 800: true); max-width: 800px" alt="" src="http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicCaS.jpg" border=0>

[civicminded]

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicCbS.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicCS.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicCaS.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/Civic7.jpg

[JanGeo]

Do we know for certain that the front wheel wells are a source of drag being open.
Are they letting air out from under the car?
Do they need to be fully enclosed?
How about smooth hubcaps and smaller openings around the tires to the fender instead of enclosing them entirely.

[MetroMPG]

Enclosed arches are best. Seems only logical. See the Ford Prove V prototype & any number of one-off Bonneville high-speed designs.

Next best is smooth wheel covers and tight tire-arch tolerances: the Prius has noticably smaller than "normal" tire-arch gaps).

A radiused shape at the "aft" end of the arch bodywork permits air exiting the wheel well to transition better to the sides when the arch is left "open": see the honda Insight, VW 1 Liter prototype.

[ZugyNA]

Has anyone thought of using one of those snow saucers to cover a wheel well?

Or maybe an old satellite dish of some type?

Maybe a hard type tire cover as on an RV?

[MetroMPG]

Do we know for certain that the front wheel wells are a source of drag being open.

FYI: Just found this (again):

From: Reducing Drag Forces in Future Vehicles
Project in the course Road Vehicle and Aerodynamic Design, MTF 235 (http://www.tfd.chalmers.se/%7Elelo/rvad/reports/rva2002_gr10_drag-reducing.pdf) (PDF)


A source of large amount of drag force is the complex flow in the wheelhouses. Covering the wheelhouses may stabilize the flow in those areas and reduce drag very significantly. However, styling and functional issues (front turning wheels) often make it hard to implement this solution.

[basjoos]

I got the 3-piece boat tail built and installed. Installed the first two pieces on thursday and drove through the weekend with it. At 28F, the car coasted as well as it used to at 90F and at 50F it coasted much better than it did at 90F. The boat tail has caused the greatest improvement in coasting ability of any single aero mode that I have installed so far. With the 2 pieces installed, I can still use the back hatch. This monday I built and installed the 3rd part (tail cone) of the boat tail, but with all of the rain today it was impossible to tell if it made any difference. The boat tail is made of an auminum bar frame covered with coroplast (bottom) and clear vinyl (upper portion). The clear vinyl makes it possible for me to see out the back and so I didn't need to relocate the tail lights and license plate. I used the Questair Venture tail cone as a model for the shape of my boat tail and did a quick run with taped yarn to test the air flow over the parts that I can see through the rear window (attached air flow all of the way to the tip). Lets see if I can get these picture to work.

2 piece boat tail
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBoate.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBoatd.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBoatc.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBoatb.jpg


3 piece boat tail
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBoataa.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBoatbb.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBoatcc.jpg

Questair Venture
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/Venture_s_th.jpg

[Matt Timion]

that thing is AWESOME!

[MetroMPG]

basjoos, you rock. :)

[zpiloto]

That's fantastic.:thumbup: :cool: I can't wait to see what kind of results you get with that. Somebody donate a SuperMID to basjoos.:D

[MetroMPG]

I noticed also the lack of passenger seat ;)

[thisisntjared]

<--awaits results. thats crazy

[MetroMPG]

this stuff makes me wish my car wasn't in such good shape. It would be fun to get out the drill and not worry about it.

[budomove]

basjoos, I would love to see a flapping tailfin on the back...no seriously that setup is sweet, and i am jealous!

[onegammyleg]

If you think that looks good , how about this ....

http://lovlig-streetrace.dk/billeder_film/ugly_car_styling_01/36.jpg

[Compaq888]

I wish I had 2 cars. One for daily driving(interior gutted, no PS, weight reduction, Scangauge 2, aero mods) and another car to take dates, go to movies with friends and etc.

[cfg83]

MetroMPG -

I noticed also the lack of passenger seat ;)

This should be a number one weight reduction item. If you have a garage to store it (no long haul to put it somewhere) and a quick-release rail system, removing it for the weekly commute would be very convenient. My Saturn uses 4 heavy bolts to connect the seat, so I would have to retrofit a slider system. I have removed the seat for moving in the past and I like the roomy feel of the interior without the seat, so it's a definite plus.

The sliders already exist for after-market seats :

http://www.safedrives.com/prodimages/momo/seats/Sliders_lg.jpg

Does the Fit have removable rear seats?

CarloSW2

[basjoos]

So far (at 210miles) my gas gause is much higher than it would normally be with this many miles on the tank, despite 120 miles of driving in rain and wet roads. The tail end of a 2 mile long coast on my way home from work really drove home the overall improvements that the aero mods have made to my car's coasting ability. At the point on the road where my car's speed would normally have dropped down to 35mph in its pre-aero days, I am now doing 50mph and I can roll on for another quarter mile down the road before I have to restart the engine.

[MetroMPG]

Eagerly looking forward to your next fill-up basjoos.

[The Toecutter]

Man, if only our cars had such a boattail built into them.

Te auto industry clainms going aero would reduce storage space, but that clearly is a crock of ****. Your design could have easily been incorporated to double usable trunk space while perhaps improving FE by 15%.

If you get 80-85 mpg highway, I will not be surprised.

[kickflipjr]

basjoos you are hardcore. I hope you see a big gain.

[theclencher]

I like what basjoos is doing for sure, but if the long term average from that boattail alone goes from 70 to 80-85 I would be surprised.

Time will tell.

[onegammyleg]

Your design could have easily been incorporated to double usable trunk space while perhaps improving FE by 15%.


Yeah , you could easily fit a body in there now , err , I mean , all your shopping :o

[thisisntjared]

i think it could even be more streamlined, the plastic behind the extends from the side windows should be angled in closer. that mid frame should be like a trapezoid instead of being a rectangle. i bet he will get great gains, but its amazing that there is still more!

[MetroMPG]

Your design could have easily been incorporated to double usable trunk space while perhaps improving FE by 15%.

If you get 80-85 mpg highway, I will not be surprised.

My tiny kardboard Kammback (I know it's not technically a Kammback :rolleyes:) netted a 2.3% gain @ 55 mph. I can't estimate what basjoos' full tail will yield, but it's going to be way more than that.

http://www.metrompg.com/posts/photos/aero-boattail-rear-s.jpg (http://www.metrompg.com/posts/boat-tail-prototype.htm)

[basjoos]

i think it could even be more streamlined, the plastic behind the extends from the side windows should be angled in closer. that mid frame should be like a trapezoid instead of being a rectangle. i bet he will get great gains, but its amazing that there is still more!

If I went with a 1 piece boattail and gave up the ability to access the hatch, I would have angled the midframe in more. But I had to keep the midframe broad enough to allow room for the lower mini-tailgate to open out.

I got 68mpg from this tank dispite 120 miles of driving in the rain. Normally at these temps and with this amount of wet road driving, I would have seen mileage in the low 60's. I've noticed the biggest effects of the boattail in high speed coasts. In 35 to 45mph coasts, there is a decent improvement over the pre-boattail performence, but in coasts where my speed peaks at 60 to 70mph there is a large difference in how far I end up coasting and rate at which my speed drops.

[Silveredwings]

Wow, that's a beautiful thing. Tell me, do you get any flutter of the clear vinyl at any particular speed?

Very inspiring. :thumbup:

[ZugyNA]

COOOOOOOOOOOOOOOOOOOOOOL.

The REALLY BIG question?

Could you get the same results from mounting a WING as with the VW?

[basjoos]

So far I have had it up to 75mph without any vinyl flutter.

A wing wouldn't be as good as a boattail. With the boattail, I don't leave any eddy turbulence behind me (its interesting driving down a leaf covered road and seeing very few leaves disturbed). The wing on the Beetle helps to mitigate some of the terrible aerodynamices of the Beetle's design, but it still leaves a big eddy behind it.

[onegammyleg]

but it still leaves a big eddy behind it.

Eddy ?
http://friends.timway.com/photos/Eddielwy/fat%20kid12.jpg

[theclencher]

No, silly! http://www.travelblogs.com/andrew/dohuk_eddie_munster.jpg

[onegammyleg]

ahh ,,the Munsters , ya just gotta luvem ! :D

[Silveredwings]

What an elegant design.

So far I have had it up to 75mph without any vinyl flutter.

A wing wouldn't be as good as a boattail. With the boattail, I don't leave any eddy turbulence behind me (its interesting driving down a leaf covered road and seeing very few leaves disturbed). The wing on the Beetle helps to mitigate some of the terrible aerodynamices of the Beetle's design, but it still leaves a big eddy behind it.

I see, that's great. I agree about the wing; you may be able to redirect the air to minimize separation but at the cost of induced drag on the wing and interference drag at the wing's pillars unless you designed complex fillets (http://en.wikipedia.org/wiki/Fillet_%28mechanics%29).

[MetroMPG]

its interesting driving down a leaf covered road and seeing very few leaves disturbed)

What a neat observation.

[FormulaTwo]

Very nice
I don't think I have had the chance to comment on this yet.
I would love to do this to my car, but I am not that far into it yet.
It really does not look bad at all. I have airtabs on the way.
I feel like it will be forth the money to test htem out, since they are only like $2.50 each.

Maybe eventually as i slowly get more hardcore about FE i will end up with a similar setup to what you have.

[basjoos]

Installed front wheel well skirts. The skirt is a made of an aluminum bar frame covered with coroplast and hinged at the top with piano hinge. There is enough tire clearance inside the skirt for normal on-road turns (lane changes, curvy roads, etc), but when I have to make a sharper turn, the tire rolls against a low profile (1/2"x6") conveyer roller that pushes the skirt out while I am making the sharp turn. Two springs at the bottom pull the skirt back in when the tire straightens out.

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBa.jpg

Front wheel well skirt
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBb.jpg

Wheels in full left turn position.
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBc.jpg

View of inside showing conveyer rollers.
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBd.jpg

[MetroMPG]

It's quite a handsome profile overall, if I do say so.

[Silveredwings]

That's ingenious.

[MetroMPG]

If ever there was someone who NEEDED a MID/SG...

It kills me that measuring the results of all this work is only as accurate as tank by tank testing. I'd love to know better controlled results. Maybe that's just me though. :o

[thisisntjared]

ah i understand the shape now. the fact that the hatch and tailgate are still accessable is amazing!

the front skirts are crazy!! hahaha

[SVOboy]

I'm spurred again to win the MID to give it to basjoos.

Actually. Basjoos, do you want to have mine on semi-permanent loan? I'm not really using it and I could send it to you for december to june when I won't even see my car. Please say yes.

[basjoos]

SVOboy,...yes. I'd be interested in the semi-permanent loan of your MID assuming I can figure out how to install it. I usually begin seeing summer heat and humidity by mid-May, so I should be able be see how far above 100mpg I can go in the car with the current (and additionally planned) mods installed by next spring.

[krousdb]

Basjoos,
I can help you install it. I live just south of Raliegh and work in Fayetteville NC. I'm sure that we cross paths sometimes.

[The Toecutter]

I got 68mpg from this tank dispite 120 miles of driving in the rain. Normally at these temps and with this amount of wet road driving, I would have seen mileage in the low 60's.

How low in the 60s?

68 mpg/60 mpg = 1.133

13.3% gain possible, but probably around 10%. That's not bad at all.



Those front skirts are insane. You're well on your way to a 100 mpg car. Now you need a diesel for it, and a huge tank for some freakish cruising range.

[basjoos]

[QUOTE=The Toecutter]How low in the 60s?

Would have expected about 62 to 63mpg.

[The Toecutter]

So worst case, that gave you about an 8% improvement. That is pretty damn good. I earlier made the error of assuming the boattail was optimized and had the proper angle. Even still, this is very impressive.

Man, I wish I knew how to do metalwork. I'd gladly make the rear end of my Triumph GT6 tapered like that. Done right, it would enhance the car's aesthetic appeal, instead of detract from it.

It's a dream of mine to have the one of the most vulgar cars on the road, and for it to be ecologically sound relative to almost everything else out there.

If your Civic were an EV, it would do 150 miles range at 60 mph on 1,500 pounds of today's 25 Wh/kg sealed lead acid batteries.

[basjoos]

Here are some photos of the current configuration of my car. Mods installed so far, listed from greatest of least effect on improving the coasting ability of my car: boattail, nosepiece, underbody panelling, grill block, front and rear whell well skirt, wheel spoilers, side spoilers, smooth hub caps, gap sealing.

Photos circling the car from front to back.
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero1.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero11.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero10.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero9.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero6.jpg

Closeups:
Front wheel spoiler
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero12.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero13.jpg
Side skirt
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero14.jpg
Front wheel well skirt and wheel spoiler
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero19.jpg
Rear wheel well skirt and wheel spoiler
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero16.jpg
Boattail
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero18.jpg
View of underside from back of car.
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero7.jpg
View of underside from front of car.
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero8.jpg

[MetroMPG]

I'd love to hear some of the comments/reactions you've had from friends/strangers. Not that it matters, but it would be interesting.

[basjoos]

I've had several people ask me if it was an electric car after an ICE-off coast into a parking lot. Others have asked me what all the stuff on the car was for. Only one person has asked me if the stuff on the car was to improve mileage. And I have had plenty of slowdowns and staring on the part of people passing me on the highway. One guy in a van passed, me, slowed way down so that I passed him, then he passed me, then about a mile up the road, he was parked on the side of the road and took pictures as I drove by.

[MetroMPG]

Funny. And to think I was self-conscious of the rear wheel skirts for a while.

Thanks for posting the pics - they're awesome. That's the kind of stuff that goes down as Internet legend, you know :) Well, in certain circles.

[repete86]

Wow, that boat tail is impressive. How did you build it?

[onegammyleg]

I think I will wait untill my Swift (metro) is worth 50 bucks before i do changes like that.

[red91sit]

Yes, I know you can't judge aero by looking at it... but unless that pointier nose is somehow directing more air away from a "dirty" undercarriage I don't see how it can be improving aero. Generally, as long as the airflow going around the front end remains attached along the sides the bluntness or pointyness of it doesn't really affect drag in the 0 degree yaw condition. In fact I wonder if the increases in "frontal area" due to the added length of nose and tail when the car is yawed serve to increase Cd in crosswinds?

Interesting points, something to consider is he has a smooth undercarriage on his eg already.

[basjoos]

Wow, that boat tail is impressive. How did you build it?

The boattail is made of an aluminum bar (1/4"x1") frame bolted together (drilled and tapped) and covered with clear vinyl on top and coroplast on the bottom. This construction is quick to go together and requires only a few tools (drill, tap, hacksaw, box cutter, screwdriver).

[basjoos]

I think I will wait untill my Swift (metro) is worth 50 bucks before i do changes like that.

So how much is a 17 year old car (1992) with 683,971 km on it worth anyway?

[SVOboy]

Send me a PM about the MID so that I don't forget about it, I should be able to loan it to you after winter break, which will be ending around the beginning of january.

[basjoos]

Yes, I know you can't judge aero by looking at it... but unless that pointier nose is somehow directing more air away from a "dirty" undercarriage I don't see how it can be improving aero. Generally, as long as the airflow going around the front end remains attached along the sides the bluntness or pointyness of it doesn't really affect drag in the 0 degree yaw condition. In fact I wonder if the increases in "frontal area" due to the added length of nose and tail when the car is yawed serve to increase Cd in crosswinds?

The great effect of that nosepiece surprised me too. I had installed it in preparation for my next mod (Re-scuplting the profile of the hood/windshield area) and didn't expect it to have the effect that it did. The only cause I can think of is that most cars have deliberately designed into them a high pressure area on the nose to help funnel air into the radiator openings. The pointier nose reduces the size of that high pressure area, and by placing the point low, diverts some of the air over the car that used to go under it.

[thisisntjared]

The great effect of that nosepiece surprised me too. I had installed it in preparation for my next mod (Re-scuplting the profile of the hood/windshield area) and didn't expect it to have the effect that it did. The only cause I can think of is that most cars have deliberately designed into them a high pressure area on the nose to help funnel air into the radiator openings. The pointier nose reduces the size of that high pressure area, and by placing the point low, diverts some of the air over the car that used to go under it.yea i was going to say cross winds usually dont get passed 40mph and are thus not a great concern. cutting that high pressure system in front of the bumper should help a great deal...

also, i think you are correct in the assumption that the auto makers create the high pressure area to aid in cooling.

[Peakster]

Holy smokes! This is the first time I read this full thread. Basjoos, your aerodynamic modifications are INCREDIBLE! I'm definitely going to at least try wheel spoilers on my car after being inspired by you!

Just one year ago, I was driving a 1985 Pontiac Fiero with a Cd of 0.37 and that number shot to 0.41 when the headlights were popped up!

[Frank]

What inspiring work! Keep it up and thanks for posting!

[basjoos]

I've noticed that the nosepiece has made a change in the A-pillar vortex. When driving in the rain, the behavior of the water drops on the side window shows me the location of the drag-inducing vortex produced by the A-pillar. It forms a comma-shaped line of stationary water drops about 2/3 of the way up the glass where the bottom of the vortex beats upward against the glass, keeping the drops suspended and not letting them run down the glass. Since I added the nosepiece, this comma-shaped line of water has shifted upward and is now located 4/5ths of the way up the glass, which I believe if indicative of a smaller-sized vortex and hence less drag.

When I gassed up today, a guy asked me if my car was an experimental hybrid.

[onegammyleg]

So how much is a 17 year old car (1992) with 683,971 km on it worth anyway?

almost as much as a Big Mac ide figure :D

[Frank]

Something you may want to try sometime is to install larger diameter tires. This is an easy way to change effective gearing which will load the engine more for a given road speed. Lower RPM at a given load usually requires more throttle which means less pumping losses which means higher engine efficiency. Or something like that. Your efficiency improvements have reduced engine load; there might be more to have...

[basjoos]

My tires are one size over stock, mainly due to limited availability of my car's stock tire size. One problem with going to a larger tire size is that it also increases the ground clearance, which tend to increase drag as more air goes under the car.

[basjoos]

As I have progressively aero modded this car, its coasting ability has steadiliy improved. To the point to where I now drive it considerably different than I have driven any other car. Since any moderate downhill grade now produces a steady accelleration, any slight downhill is now a steady speed coast, and it takes a long time to lose speed when coasting on a flat grade; in any kind of slightly rolling terrain, I find myself spending a good chunk of my driving time in ICE-off coasting mode.

[basjoos]

I finally found and installed a good interior rear view mirror on the left and right sides of my car. I also cut off the rear view mirror mount on the side of my car and finished it off smooth. The interior mirrors work fine for rear view vision and also allows me to get closer to the mailbox to pickup mail since I don't have an exterior mirror to risk hitting the box with.

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/Mirror.jpg

[SVOboy]

How much and where from!?

[basjoos]

$1.89 each from Wal-mart. I attached it to the door with a strip of velcro.

[thisisntjared]

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/Mirror.jpg
any notable change? i remember seeing that it doesnt really do much in another thread a year ago, but on your car the change would make more of an impact since theres so many other mods done.

do you guys know which side will pass inspection with the mirror missing?

[basjoos]

Since the state just got hit with a massive cold snap, there has been too much of a termperature change for me to know how much effect it had on the mileage. The mirror isn't missing, its just been relocated to the other side of the window glass. Fortunately, South Carolina stopped doing annual automobile inspections back in the early nineties, so I don't have that B.S. to worry around.

[Silveredwings]

Your car is looking more like an aircraft all the time. :thumbup:

[basjoos]

Here's my last major aero mod, second windshield covering the area from the front of the hood to the top of the windshield. This should get rid of the "A" pillar vortexes. I also added an outer side skirt so I have one side skirt parallel to the iinner edge of the tires and another side skirt parallel to the outer edge of the tires.

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero20.jpg

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/aero21.jpg

[zpiloto]

That's awsome! Have you had any probems with law enforcement? What's left to do on the car now?

[Silveredwings]

That's just sick. And when I say sick, I mean 'cool' way outside the box.

[thisisntjared]

AMAZING!!!! just when i thought that there was not any more to do!! where is the scangauge???? i want to see that these mods work well!!
That's just sick. And when I say sick, I mean 'cool' way outside the box.
punn intended?

zpiloto is right, whats left for aero?

[Silveredwings]

zpiloto is right, whats left for aero?
There have been other radical attempts to do the teardrop thing:
Paul Lewis' Fascination cars:
http://www.jacksonville.com/autos/stories/071505.shtml
1937 Airomobile:
http://mywebpages.comcast.net/airomobile/hemmings.htm
Bucky's Dymaxion car:
http://en.wikipedia.org/wiki/Dymaxion_car

[basjoos]

So far, I haven't had any problems with law enforcement. The main other project I want to do is to add a manually adjusted air intake to the nosepiece/grill block so I can tailor the amount of cooling air needed to the amount of cooling actually required. Cooling isn't a problem this time of year, but in the summer, it would be nice to be able to close off the air intake when driving at night or other times when the temps are low.

The second windshield added about 4mph to my terminal velocity on the "calibrated" downhills on my drive. I drove through some light rain and didn't even notice it on the vinyl other than the occasional drop running back along the vinyl. Most of th rain (and bugs) follows the smooth airflow over the vehicle. And best of all, no evidence of the "A" pillar vortex based on the behavior of the water droplets on the front side windows.

[red91sit]

I can't wiat to see your next gas mileage log!!!!

Your a big inspiration to me (uhmm yeah now i fell like a girl, thanks a lot)

[The Toecutter]

God damn, this thing probably gets like 80-85 mpg at 60-65 mph now...

[basjoos]

Fun experiments! :thumbup: I wonder what the Cd is now?

Phil Knox looked at the photos of my car and estimated the Cd to be around 0.16.

[MetroMPG]

As far as I'm concerned, your car and Phil's truck are the benchmarks of the DIY aero-modding crowd.

[Silveredwings]

Phil Knox looked at the photos of my car and estimated the Cd to be around 0.16.
It is pretty amazing. I think you may be at the point where further aero improvements will require smoothing the fairings to reduce the parasitic surface friction.

[Frank]

Very impressive! Way to go!

[CO ZX2]

Hello from Colorado. I have been parked in a snowdrift for the best part of the last month. Hope you can do better than that. Anxiously awaiting your test results. I have a question: I spotted a VX on ebay. Can you decipher the serial# and tell me if it matches for a vx. Thanks CO ZX2
http://www.autocheck.com/?siteID=204&vin=2hgeh2372ph543439

[basjoos]

I don't have a VX (mine is a CX with the engine from a DX), but that VIN looks like a VX to me.

The following site has a good rundown of the Honda VIN:

http://members.lycos.nl/hendrik/honda/vin.htm

2HGEH2372PH543439

2=Canada
H=Honda
G=Passenger Car, Built in USA/Canada
EH2=Civic 3 Door, 1.5L
3=3 Door Hatchback, Manual
7=VX Civic
2=check digit
P=model year 1993
H=Alliston, Canada
543439=production sequence number

[CO ZX2]

Thanks, basjoos for the serial# info. Appreciate it. Is it wintertime in NC?

[basjoos]

If by "wintertime", you mean the presence of frost, yes we have had a lot of below freezing nights in Nov and Dec. If by the presence of snow, I haven't had any here yet this winter in SC, but the Asheville, NC area where I work had a number of under 2" deep snowfalls. But lately, the temps have been in the 60's days, 40's nights, the frogs are singing up a storm in the ponds around the house and I am leaving the windows open at night. Feels like April.

[CO ZX2]

If by "wintertime", you mean the presence of frost, yes we have had a lot of below freezing nights in Nov and Dec. If by the presence of snow, I haven't had any here yet this winter in SC, but the Asheville, NC area where I work had a number of under 2" deep snowfalls. But lately, the temps have been in the 60's days, 40's nights, the frogs are singing up a storm in the ponds around the house and I am leaving the windows open at night. Feels like April.
Do you ever go frog hunting? When I was a kid in Virginia I went with my granddad and uncle a few times. At night with homemade gigs. We ate 'em, not too bad.

You are gettin' after it with the gas mileage. Good job. Read about your encounter with the fuzz. Happy he didn't haul you away. Now he will have something to tell his grandkids.

I've wondered where you park your car when you're in town and at work. Even with the mild mods that I have, when I go to the grocery store or Home Depot, sometimes there are people standing around the car looking and talking. I can imagine your plight.

[SVOboy]

Have you ever considered taking the plunge and getting a VX? Or perhaps just the drivetrain? I wonder if the CX engine would perform better with all the aero mods because of reduced load...Hmm.

[red91sit]

That's funny- I was thinking of starting a thread with that topic. My harlequin car with campaign sign rear skirts, blocked-off grille and custom round sealed beam lights for some reason attracts an inordinate amount of attention! The teens and 20-somethings seem to love it the most, doing double and triple takes, pointing, smiling, laughing... :eek:

Must get pictures! BTW- E-85's freaking awesome.

[brelandt]

That's funny- I was thinking of starting a thread with that topic. My harlequin car with campaign sign rear skirts, blocked-off grille and custom round sealed beam lights for some reason attracts an inordinate amount of attention! The teens and 20-somethings seem to love it the most, doing double and triple takes, pointing, smiling, laughing... :eek:


Dude start one, really. since I'm new to this and live in Redneck land I HAVE to hear what everyone else goes thru in and around their hometown.

So far mine just looks like I live in a ditch with no future. just wait and see if I start areo modding the thing out?

[basjoos]

CO ZX2
I have never gone frog hunting, but have no problems with eating frogs (as long as it isn't the poisonous pickerel frog).

Since my car is my daily driver, I park it wherever I need to go and have had people come up and ask me about it ("Is it an electric car?", "Is it a hybrid?", etc). But I do try to position it in the parking lot where it is less likely for someone to back into the boattail.

SVOboy
At various times I have considered getting a VX, but never got around to it since I am getting such good mileage out of this one and stock VX's are hard to find. When the engine and/or transmission wear out on my CX, I'll consider replacing them with a VX ICE and tranny. With the aero mods installed, the CX engine would perform the same at slow speed and would perform better at higher speeds than the vehicle with stock aero. Compared with the original CX motor, the DX motor currently installed has slightly less torque at low RPM's and much more power at high RPM's. Provided I keep the RPM's below 3000, there was no change in mileage as a result of the engine swap. So I have more available power for those occasional times when I need it combined with no drop in overall FE.

[basjoos]

After the discussion with the nice cop, I relocated my licence plate to a location in the dirty air just behind my muffler where it is readable from behind, but should do minimal additional damage to my car's aerodynamics.

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/License1.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/License2.jpg

[basjoos]

I finally finished installing a complete set of taillights (lights, brakes, direction) in the tip of the boattail.

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicBoatf.jpg

[red91sit]

why not put your license plate up in the boat tail tip as well?

[Silveredwings]

I think it has to be outside the plastic, so he's located it as much out of the slipstream as possible to remain legal (prob had to locate a light for it too).

[kwtorbe]

I've used Dzus fasteners in the past for hoods, bumpers, front ends, etc... should be great for what you need.

Reading this forum this is exactly what I was thinking. I installed a fiberglass 6-pack hood on my '70 cuda using Dzus clips. They work great and you can get them from your local race store.

[BeeUU]

Great work, kicks the #$%#$ out of anything I have done. I will have to use your photos to soften my wife's response to future areo mods on my car.

Thanks for leading the way basjoos.

[itjstagame]

If the wind is nearly parallel to the path of the car (or dead calm), then the air only gets moved out of the way once, out of the way of the first wheel. Now that I understand the effects of crosswinds, I am reluctant to try side skirts, because they will slow you down with a crosswind.

I didn't realize the side skirts were only for the movement of air around the tire, if so, wouldn't it be better to just expand on the wheel spoiler concept? That is, have a spoiler in front of the tire to move air down and around the tire better than just hitting the wall of rubber, and have the same thing afterward to help the air join better instead of just having a massive negative pressure region behind the tire (same concept as the tail on a smaller scale).

Also awesome project, I can't wait to get a daily commuter beater to do this to. Does anyone have any good sites to look up local laws? Because some of these mods seem quite over the top and I'm not sure how much of a stickler NYS is.

[Bill in Houston]

That is, have a spoiler in front of the tire to move air down and around the tire better than just hitting the wall of rubber, and have the same thing afterward to help the air join better instead of just having a massive negative pressure region behind the tire (same concept as the tail on a smaller scale).I think that the difficulty comes in trying to allow the "wheel spoiler" to move up and down with the suspension, and turn from side to side.

[basjoos]

Some people were asking questions recently about installing grill blocks on 92-95 Civics. I've had this grill block installed since last Nov, and it hasn't shown any signs of overheating dispite 105F summer temps here in SC and steep climbs up into the NC mountains. The grill block is a rounded nosepiece that replaces the flat surfaces of the original grill/bumper and I use the slot at the front of the hood as my air intake. The radiator in this car sticks a few inches above the lip of the hood opening with a gap in front of it, so the air enters the hood slot, hits the top of the radiator and curls down into the space between the front of the radiator and the original grill openings. I removed the rubber gasket that normally seals the slot at the front of the hood and caulked the part of the hood slot that sits in front of the AC radiator (which doesn't stick up). Air for the AC radiator runs down through some widened holes in the area around the hood release. This mod caused a noticable improvement in coasting (this was in my pre-SuperMID days so I have no hard and fast numbers) and cut the size of the A pillar rain swirl vortex to 1/3 of its original size (= less aero drag). Since this radiator intake is invisible to most people's eye, I've gotten more questions as to whether my car is an electric vehicle since I installed it (often asked after I coast silently, ICE-off, to a stop).

http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/GrillSlot.jpg

[basjoos]

The boattail I built last fall on my 92 Civic was so effective, FE-wise, that I decided to make it a permanent addition to my car, replacing the Coroplast and clear vinyl boattail with one made of aluminum sheet and Lexan. I recycled most of the original aluminum bar framework in the new boattail and the new boatttail has the same proportions as the old one. Used pop rivets to mount most of the aluminum sheet. I extended the car's cargo area into the boattail, so now with the back seats down, I have 6-1/2 feet of load floor (4-1/2" of cargo space behind the back seats when I'm carrying 4 people). I also installed a functioning hatch (the stock hatch was covered by the original boattail).

I had the Civic off the road for over a week while installing the mods, during which time I drove our Honda Odyssey and Ford F150. When I first took the modified Civic out for a drive after a week's worth of getting used to driving "normal" vehicles, I was impressed by how differently it drove than your typical vehicle. Most cars slow down fairly quickly when the power is cut, especially at highway speeds, but the aerocivic only very slowly loses speed when power is cut. It makes a normal car feel like driving around with the parking brake lightly engaged.

As time allows, I plan to replace the coroplast on the front wheel skirts and nosepiece with Al sheet. The underpanelling, side skirts and wheel spoilers will remain as coroplast since coroplast's flexibility allows it to better withstand contact with road debris than the rigid aluminum.

Following are steps in the construction process:
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild1.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild3.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild4.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild7.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild8.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild10.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild13.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild11.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild15.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild16.jpg
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/BoatRebuild17.jpg

[AmmoCatcher]

How'd you get the Lexan to bend without breaking/crazing? I'm wanting to do something similar with my del Sol and haven't got the nerve up to do it yet. :rolleyes:

[jwxr7]

that looks really good :thumbup: . Space age looking, and kind of airstream travel trailer crossed with airplane before paint. That makes me want to upgrade to a full boatail soon :D . Does your middle upper brake light still shine thru good? I know in michigan that could get a car pulled over. We don't need any more excuses to get pulled over.

[SVOboy]

Wow! That's amazing dude! I can't wait to see what you do when you replace the rest of the stuff.

:thumbup:

[Danronian]

Wow. Looks like it was really planned out. It came together nicely this time around.

[Nerds laugh at me]

I wish I had the balls to do something like this.
Basjoos -I'm really impressed !


I wanted to ask about your grill setup. You say that the engine takes in air from the hood slot since you removed some of the weatherstrip there.
Other than removing the weatherstriping, did you raise the radiator or do any other sort of mods? What does the temperature guage read ?
Thanks a lot for sharing the info.

I also wanted to ask what advantage that adding the spike nose has to the car.
I notice that there are plenty of cars that not only have blunt front ends - but almost a brick like shape to the front end ( the Ford Fusion that was posted here that has a .21 Cd, the Opel G90 at .22 Cd ( and both of these cars have no boat tail or wheel covers) as well as the new Cadillacs.
At subsonic speeds, from what I have read a rounded front end is more efficient.
Just asking ( educate me ;-) ! )

I read that a steep windshield is just for looks once it passes a 45 * angle.
This info was from the guy that did the aerodynamics on the EV1.
So what advantage did the extended winshield have ?

Thanks !
I appreciate your hard work and any info you share with us !

[basjoos]

How'd you get the Lexan to bend without breaking/crazing? I'm wanting to do something similar with my del Sol and haven't got the nerve up to do it yet. :rolleyes:

You can bend Lexan with a metal brake. I used 1/8" Lexan, which is easy enough to bend into place with the application of some body english and then secure with screws.

[basjoos]

that looks really good :thumbup: . . Does your middle upper brake light still shine thru good? I know in michigan that could get a car pulled over. We don't need any more excuses to get pulled over.

No problem seeing the middle brake light.

[thisisntjared]

i love it! keep it up. it looks a lot better now!

[basjoos]

[QUOTE=Nerds laugh at me;74126]
I wanted to ask about your grill setup. You say that the engine takes in air from the hood slot since you removed some of the weatherstrip there.
Other than removing the weatherstriping, did you raise the radiator or do any other sort of mods? What does the temperature guage read ?
Thanks a lot for sharing the info.

I also wanted to ask what advantage that adding the spike nose has to the car.
I notice that there are plenty of cars that not only have blunt front ends - but almost a brick like shape to the front end ( the Ford Fusion that was posted here that has a .21 Cd, the Opel G90 at .22 Cd ( and both of these cars have no boat tail or wheel covers) as well as the new Cadillacs.
At subsonic speeds, from what I have read a rounded front end is more efficient.
Just asking ( educate me ;-) ! )

I read that a steep windshield is just for looks once it passes a 45 * angle.
This info was from the guy that did the aerodynamics on the EV1.
So what advantage did the extended winshield have ?
QUOTE]

The radiator is in its stock position. The top of the radiator sticks up above the level of the hood slot and scoops the incoming air down in front of it so it can pass through the rest of the radiator. I've never never had any overheating problems with the current setup dispite this summer's 103F highs. The temp needle has never climbed above its usual location of the gauge, which it did with some of my earlier experiments at grill blocking.

All I know is that when I added the nosepiece, it coasted better and it reduced the size of the A pillar vortex by about half. This was in my pre-SuperMID days, so I don't have an exact MPG figure for it. I based its shape on that of modern aircraft noses, none of which are brick shaped, and all of whose Cd is well below that 0.20 figure that the car designers are aiming at.

The extended windshield eliminated the A pillar vortex completely and also the high pressure zone at the base of the stock windshield. This high pressure is what pushes air through your air vents when the fan isn't running and some performance cars have a raised hood open to the base of the windshield that uses this high pressure air for engine intake air. I based the shape of my extended windshield on the windshields of modern composite aircraft, such as the Cirrus SR20. I plan to re-glaze the extended windshield with Lexan and then do some tests with and without it.

[Nerds laugh at me]

Thanks basjoos !
Looks like your experiments are helping us all !
Much appreciated !
I need those happy face icons so you guys read my comments in the right tone.
When I said that stuff about the winshield angle and nose cone ( as well as some other comments I have made in the past ) I was in an inquisitive tone.
I'd like everyones opinion. I'm just asking because I see a lot of conflicting stuff.
Here is some Photoshop doodles. I hope you don't mind me drawing all over your car.
What would look better in my opinion would be to black out certain areas using flat black paint. Gloss would show the dents toowell and run - as well as look cheap. Flat( matte) would have a more professional look to it.
You could do it with spray cans and if you wet sanded it afterwards with superfine grit wet-dry sandpaper, it would get rid of the spray can look that makes a car look awful.
As far as those air deflectors n the sides and on the top, they would help shape the cars profile to something more ... racy but would be fully functional.
In fact, MetroMPG added some on his test with wheel covers and they increased the MPG percentage quite a bit !
I have planned to have these on my car for years, but have just chickened out - and besides iwas not sure if 'squeezing the air into a smaller wake would work .
Apparently it does !!
As far as the fins on the top, they would help to cut the phallic look of the back end and ..yup they too would be functinal by pinching the air into a smaller wake as well as channeling the air like a vertical stabilizer on an aircraft.
Also they look racy. Many Top fuel funny cars have these ( although inbetween the vertical stabililizers is a wing to create downforce - something you could omit.
The arrow in the image points to a car called 'Blowfish' that Hot Rod built to run at Bonneville. Note the tail.
Let me know what you think !

Something I have been wanting to ask you from the start of all of this ..of all the things on a car that are not needed, why do you still have your radio antenna out in the breeze ??
I removed mine and only noted a slight difference in reception. I pushed it down into the antenna hole and had it make contact with the metalbody - acting as a huge antenna itself.
Strangely enough even the tiny wire that serves as an antenna has a small effect on your ,Cd ( Besides there is the base which stick up about a quarter inch. Why not flatten that sucker out ?

[Nerds laugh at me]

Duh might help if I added the pictures http://farm2.static.flickr.com/1228/1449647481_a338b1fc55_o.jpg

http://farm2.static.flickr.com/1218/1450506388_a9716f065a_o.jpg

[McPatrick]

That is simply awsome! If this starts looking any more professional you can start selling aftermarket kits for Civic Hatchbacks :)

Do you detect any difference in mpg between the old and new boat tail?

[brucepick]

Basjoos, you're an inspiration to us all!
Your work shows what CAN be done if the designers would just DO IT.

Count me as another one here wishing I had the um, cajones, to do a real boattail and nose treatment. A moderate nose job is currently in the works for Sven. Not an extended nose, but it should be better than the current one. I'll share pics when I get it in place.

[TomO]

I really like the new tail! I wish I had teh space in the garage to do that myself. But where I live, a civic sitting outside is as good as stolen. :(

[MetroMPG]

Another thumbs-up job, basjoos. Nice work.

[basjoos]

Something I have been wanting to ask you from the start of all of this ..of all the things on a car that are not needed, why do you still have your radio antenna out in the breeze ??
I removed mine and only noted a slight difference in reception. I pushed it down into the antenna hole and had it make contact with the metalbody - acting as a huge antenna itself.
Strangely enough even the tiny wire that serves as an antenna has a small effect on your ,Cd ( Besides there is the base which stick up about a quarter inch. Why not flatten that sucker out ?

The antenna has gotten frozen (rusted?) in the extended position dispite an application of Kroil to try to free it up. I live in a rural area, so I need every bit of reception I can get. Eventually I plan to do something (internal antenna, possibly in the Lexan hatch), but its low on the list of priorities for now.

A vertical stabilizer on an airplane is there to keep it pointed into the wind. I don't really want my car to try to start pointing into the wind every time I hit a strong crosswind.

[basjoos]

Do you detect any difference in mpg between the old and new boat tail?

Both boattails have the same shape, so there shouldn't be any change in mpg. I haven't noticed any change on the SuperMID or in the car's coasting performance.

[McPatrick]

Ok, just wondered because you have taken the back hatch out and even though the new boattail might be somewhat heavier I figured you still lost some wait on the whole 'ensemble'.

[basjoos]

I did some minor tweaking to my car's aero. Did away with the last vestige of flat surface on the back of my car, the back side of the muffler. I made an aluminum fairing that blends into the bottom of the boattail.
Stock muffler
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/MufflerStock.jpg
Faired muffler
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/MufflerFairing.jpg
Pic of my car
http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/CivicView.jpg

[thisisntjared]

hmm i dont know if i agree with the last bit. its good to have a small low pressure zone behind the muffler to help draw out exhaust gasses...

i agree something should be done to make it better than the way it was and i bet what you have is an improvement, but i think there has to be a better solution.

[trebuchet03]

I did some minor tweaking to my car's aero. Did away with the last vestige of flat surface on the back of my car, the back side of the muffler.

If you make the exit like a flat nozzle -- you'll add a littler energy to the diffuser's boundary layer -- in theory, make it stick a little longer :thumbup:

[Mighty Mira]

Hi basjoos,

I thought I'd say hello from a long absent spell on the forum. Work recently required me to make a lengthy commute and I had a look to see what progress you had made. I was amazed at what you have created! Well done!

My only questions are in regards to the underside of the boattail - have you tested with and without? With mpg meter or tuft testing? I'm not sure that an angle as extreme as that of the top will work (which it appears like it is, correct me if I'm wrong), because the air filling into the gap on the bottom must come from only the sides, as the bottom is road and not a whole atmospheres worth of air. Which is why you see that most solar cars have a flat bottom.

BTW I had some time off recently and resolved to do a bunch of mods because my confidence was such that most of them would work, I can always pull them off later and test them one by one, once I have a supermid or such. I'm most of the way there - full aluminium undertray, grille blocking, front deflectors, partial boattail (extends back 1 metre from the top), left external mirror removed, rear skirts. Pictures to follow soon.

Like you I am noticing the difference in maintaining speed on coasts, increase in terminal velocity on particular hills, increased apparent power at higher speeds, lower throttle required to maintain speed. And I'm also noticing that I'll be about 100km past where I used to have to fill up.

My car also probably generates more conversation and stares than your average Ferrari. I gather this is the case for you too.

[Hateful]

Not sure how far I'm going to take the aerodynamics on my Cavalier, but I'm sure it will be a lot more than if I hadn't seen this site and the work Basjoos has done.No shortage of imagination here I see. Of Course if I payed 50K for a prius I'd be a little slow about mods too. ( shock therapy is a little out dated anyway:) )

[thisisntjared]

Not sure how far I'm going to take the aerodynamics on my Cavalier, but I'm sure it will be a lot more than if I hadn't seen this site and the work Basjoos has done.No shortage of imagination here I see. Of Course if I payed 50K for a prius I'd be a little slow about mods too. ( shock therapy is a little out dated anyway:) )50k for a prius????

[basjoos]

Hi basjoos,

My only questions are in regards to the underside of the boattail - have you tested with and without? With mpg meter or tuft testing? I'm not sure that an angle as extreme as that of the top will work (which it appears like it is, correct me if I'm wrong), because the air filling into the gap on the bottom must come from only the sides, as the bottom is road and not a whole atmospheres worth of air. Which is why you see that most solar cars have a flat bottom.

Like you I am noticing the difference in maintaining speed on coasts, increase in terminal velocity on particular hills, increased apparent power at higher speeds, lower throttle required to maintain speed. And I'm also noticing that I'll be about 100km past where I used to have to fill up.

My car also probably generates more conversation and stares than your average Ferrari. I gather this is the case for you too.

I went with a sharper than optimum angle on the bottom of the boattail for 2 reasons. I have a steep driveway entry angle and didn't want to drag the boattail bottom when entering it. Secondly I didn't want the boattail to extend more than 4 feet beyond the back axel to keep the tail from sticking out too far on the outside when making a sharp turn. If I went with a shallower bottom angle on the boattail, I would have had to extend the tail for another foot or two beyond its present length. The solar cars can get away with a flat bottomed boattail since they typically have very little body height to have to taper down from.

I typically get lots of gawkers and photos taken where ever I drive.