My new hopefully more aero Metro front bumper
 

Parts I used:
Colored Plastic Rolls, 25 Ft. - Speedway Motors, America's Oldest Speed Shop
3/16 Inch Back Up Washers - Speedway Motors, America's Oldest Speed Shop
Tru Rivets, 3/16 Inch Large Head - Speedway Motors, America's Oldest Speed Shop

Here is what the car looked like to start with. The mesh used is from a satellite dish. It looked pretty nice and blocked some air from going through but it wasn't good enough. Also the air dam was farther back than ideal so it wasn't really helping much.

http://i1288.photobucket.com/albums/...ps8135f88b.jpg

I took that bumper off since it was nice and damage free to save it. I used the old bumper from the hybrid convertible metro that was pretty beat up already so nothing lost by cutting it up a bit more. First thing was fit it on the car.

http://i1288.photobucket.com/albums/...psa1acd0fe.jpg

Then get the plastic and get it more or less in position where I wanted it.

http://i1288.photobucket.com/albums/...ps7eee82b3.jpg http://i1288.photobucket.com/albums/...ps4fe6d7c2.jpg

Once I got it where I wanted I put a rivet in one corner and used a pair of vice grips and a ratchet strap to pull it tight over the bumper on the opposite corner. Once I adjusted it and got it sitting square. I put a rivet in the center top and the other side. That let me take the bumper off and put plenty of rivets across the top of it to make sure it is good and secure.

http://i1288.photobucket.com/albums/...ps33710510.jpg

It took a bit of trimming the top edge to get the lip exposed so I could remount it on the car.

http://i1288.photobucket.com/albums/...psf57a04db.jpg

Then to brace it up I used the aluminum frame from that same satellite dish since it was curved perfectly to match the curve of the car to build a lower brace. I used a couple of bolts and self tapping screws to mount it under the car.

http://i1288.photobucket.com/albums/...ps59a4ad54.jpg

After that all I had to do was trim up the sides and make some brackets to hold the bumper out to cover the front edge of the tires. I used a couple of shelf brackets I had laying around that fit and worked good. And I used another small section of dish frame to form the sides of the bumper.

http://i1288.photobucket.com/albums/...ps054ddcda.jpg

All that was left was cut out the signal light openings and mount the lights. I cut the mounts out of the old bumper before I riveted on the plastic. I used them to make paper templates and fit them to the car till they looked good and were level then cut them out. I used rivets to attach the signal mounts to the plastic and mounted the lights.

http://i1288.photobucket.com/albums/...ps77ece0ae.jpg http://i1288.photobucket.com/albums/...ps0dbcf75f.jpg http://i1288.photobucket.com/albums/...ps32b3ac4e.jpg

I will have to see how well it works over the next few weeks. It looks pretty good so tomorrow while it is daylight I will get some good pictures of it.

Are you going to put sports lights in it like your avatar? :)

I'd say your in the running for some sort of prize, but ...a couple questions.

Are the ends of the aluminum brace rounded enough they're not going to poke dents in the plastic from the backside?

Why didn't you get the 10' roll?

The only thing I might add to that bumper is maybe a small grille opening if it needs it to keep the fan from cycling a lot. I will have to drive it for a while and see how it goes. The aluminum brace ends well before the corner. I didn't bother trying to make a frame in the corners that way if it hits something it might flex instead of crack hopefully. I got the 25ft roll so I have enough to use for my kit car Metro project sometime in the future when I get back to building on it. I did get a roll of white and am thinking since it is so easy to work with I might as well make a kammback.

I am hoping this helps the 181/181 cam I have in the car at highway speeds and can get me reliably over 60mpg on my normal commute. This car already has weight reduction and a slightly more aero back bumper. It is another leftover from the old Metro project :) At least it lets the air pass through better than a solid bumper.

http://i1288.photobucket.com/albums/...psde06e844.jpg

What is that red car in the lower right corner?

Coyote X lives!!

Patrick: it's a Manta kit car.

Coyote: that's along the same lines as the massive air dam/bumper I tested on my Firefly. I also angled mine to drop the stagnation point, though yours is a lot more cow catcher-y than mine was:

http://ecomodder.com/imgs/airdam-side-close.jpg

I A-B-A coastdown tested mine, and it showed promise: http://ecomodder.com/forum/showthrea...down-9732.html

.

This is what I want to do to mine. Can't wait to see your results.



>

Pretty sure that's a Coyote X (as per the user name. :D ). They used them for an old TV series called Hardcastle and McCormick. Awesome looking kit cars.

Interesting......

I was worried it may end up looking like this.

http://toyotacelicamodifications.com...eme_cars11.jpg

http://i1288.photobucket.com/albums/...psd00c2000.jpg http://i1288.photobucket.com/albums/...ps920e1fb8.jpg

It actually sits higher than the stock bumper with the fiberglass lawn edging on the bottom so hopefully it won't drag on much.

Looks good and pedestrian friendly. A little higher will compensate for reaching further forward in the approach angle.

Cant wait for the outcome. I notice the car manufactures are more focus on a flat front end where as the project cars and such for eco challenges go for angles, points, etc.

http://i1288.photobucket.com/albums/...psd00c2000.jpg

looks good so far.

There was a thread on stagnation point a few years ago, with the below image in the lead post. Very useful discussion. Here is the key post in the thread, besides the first: http://ecomodder.com/forum/showthrea...tml#post167922

http://ecomodder.com/forum/attachmen...6&d=1269631462

That might be for crash safety? Flat bumper has a better chance of making it out of a low speed collision alive maybe. Since the whole front end has a lot of stagnant air I would guess that the front splitters people like to add have the same effect as angling the front end (let's ignore for now the fact that sometimes these splitters can actually make the aerodynamics worse) but you almost never see them on factory cars. I bet this is for collision safety.

Approach angle.

No way. I thought we disproved this?

Oooh yah, speed holes!
http://ecomodder.com/forum/showthrea...mpg-20113.html

One advantage of an angled front bumper is it acts as a wedge to lift deer over the top of your car with minimal damage to the front of your car when you run into one. Instead of a flat bumper absorbing the collision energies, the angled bumper redirects the collision energies upward. I've had this happen twice with the aerocivic, two deer collisions at 45mph, two deer lifted over the top of my car with only a slight dent in the hood and a cracked headlight lens to show for it.

Have you ever looked under a metro back end and seen how low the bumper is compared to everything else under the back? I would probably have to cut 6 inches off the bottom to get it level with the rest of the underside.

Besides it proved itself in this situation with coastdown testing. I have a 4% grade that is 2 miles long that I use for all my coastdown testing.

The front bumper really makes the car drive different. With all the air going over the top of the car it feels like I have sway bars. It keeps the front end planted solid to the ground, so a sharp curve I can normally take at 35 with a bit of tire squeal I took at 40 with no squeal today. I kind of like the way it makes the front end seem much more stable than a Metro ever did at 70mph. I think the bumper is helping the car though I had a really hard time holding 55 and was constantly drifting up to 60-65mph today. The car just felt like a different car. I normally get 60mpg on the trip I did today of about 40 miles. Today I got 66mpg. One day doesn't mean much but from the feel of the way the car coasts it has to be an improvement. I will need to cut a small vent into it since the fan was cycling while I was driving.

On that chart it shows a bit of air going under the car is ok. If I bent the bottom inch or two under to get more of a point does anyone think that would be better than the way it is now? I could probably just build a small lip under the radiator to push the underside air through the radiator and save from cutting a vent hole in the bumper If I did.

Here is a preview of tomorrow's post if I get time to get it done
http://i1288.photobucket.com/albums/...ps57336dee.jpg

With the bracing I have on it I am hoping if I did hit a deer it doesn't do much damage to it. But my car is still not quite that smooth so there is a lot of solid stuff to hit.

I have decided these colored rolls of plastic are the best thing ever made for mods. Way easier and nicer to work with than coroplast. A small amount of heat will let you form it to just about any shape you could imagine.

I was going to do a writeup on putting the kammback on but after starting on it I was done about an hour later with a really nice looking setup.

It was a matter of attaching a 1 inch wide strip of 1/8 thick aluminum to the lip so it would hold its shape then clamping it into place and drilling/riveting it on.

http://i1288.photobucket.com/albums/...pscd3e6172.jpg http://i1288.photobucket.com/albums/...psd57b2d60.jpg http://i1288.photobucket.com/albums/...psd267b141.jpg http://i1288.photobucket.com/albums/...ps181fd151.jpg http://i1288.photobucket.com/albums/...ps94c8ba2a.jpg

Nice work on the kamm back and I like the miniskirts for the wheels. You know, the "speed holes" in your rear bumper would be good for ventilation of exhaust system heat after you build your undertray. They'd be ideal then, as vents for the rear diffuser. Are you planning an undertray?

Agreed- I think the airdam and kamm are nicely done and I expect them to provide positive gains. The mini-skirts... mmmm... I'd like to see them go down to at least axle level... can't say if they're effective as is although as a general rule mini-skirts are very effective! :eek: And you know what I think about rear bumper holes, although cal is right, with a full pan they ought to keep temps in check.

What is it called? What's the material? Are you using a heat gun to soften them?

Looks like good stuff.

it's in the first post.
Colored Plastic Rolls, 25 Ft. - Speedway Motors, America's Oldest Speed Shop

The back bumper is not really anything great I already had it from the convertible project so I stuck it on this car. I can't remember the exact numbers but on my coastdown hill I think I went from a peak speed of 75mph to 78. About the same difference in speed as rolling down a window without the wing windows open. So it isn't much really. Cutting the section of the bumper that hangs below the rest of the underside would be much better but swapping covers was much easier and quicker and leaves me a good cover to put on it when I sell it. Next time I get the car in the air I will take a picture of the underside so you guys can see how far down the bumper hangs into the wind. I figure most cars have a decent shape to their bumpers and ventilating it won't help but not every car is the same. Now if I was drilling holes in the bumper of my Volt you guys could rightly call me goofy :)

The mini skirts are an afterthought. I had a strip of plastic from cutting the back and was only that thick. So I figured why not and slapped them on. If they don't work I can always make a larger set. I am not out any material since it was just scrap pieces anyway. One day in I will be driving in the rain and stick a camera out the window and see if they work, if not I will make bigger ones.

I just took the car out for a quick drive and it seems like it coasts much better than before. If they were not patrolling heavy where I normally do my coast down test I would probably go out and try it this week. I don't think they will buy my excuse doing over 80mph in a 65 of just testing my car out :)

http://ecomodder.com/forum/283151-post54.html

http://ecomodder.com/forum/280092-post5.html

I suppose it's something like tailgate up for pickups- capture a rolling wave.

Good result so far. I'm curious about your coastdown hill. I found one that has good turnarounds top and bottom, but the run-out area is too short.

What drop in elevation over what distance? How long is the run-out? How many runs are possible in, say, a half hour?

You really need to study the MetroMPG cars and basjoos's aerocivic threads on this forum. Many cars of the 1990s have that parachute back bumper cover, mine included. But although cars vary, in three and a half years of heavy use of this site, I never remember any of the best experts here suggesting anything other than a belly pan and diffuser as the cure for the bumper-cover parachute. Did you look at the chart of stagnation point and drag changes I post in this thread earlier? If you find your results disappointing on your nose (if) you might want to consider changes that would lift the stagnation point higher, since the ideal point on that chart is significantly higher than your current build. But yours might work wonderfully... as you rightly say... cars vary.

I am thinking of folding the bottom half back inward to get the stagnation point a bit higher. Right now it has a huge amount of down force on the front end of the car and I am sure that is not helping the mileage. I am thinking that where I put that brace, as seen by the rivets in the middle, is probably a good place to heat and bend it back. I can then use a small lip under the radiator to direct air through it and solve the fan cycling all the time while driving. On that chart it is hard to find an exact number where to make the fold but I figure anywhere is going to be better than all the way at the bottom.

My coastdown hill I normally use is Bing Maps - Driving Directions, Traffic and Road Conditions It shows 2.2 miles and from ~4000ft to 650ft elevation. At the top of the hill just over the peak there is a sign that I can get up to 50mph when I pass. I pull the car into neutral and use the engine kill button. I then just roll down the hill and get my peak mph right at that sharp curve near the bottom. If there is no traffic and I can take the curve at full speed then to be much more accurate I can let the car continue to coast back down to 55mph. That happens around the B marker. I have tried different things to measure the accuracy and on back to back runs I have seen a difference with just the wing windows open when coasting back down to 55. I usually watch for some reference at the bottom that I pass right when the speedometer hits 55. There are usually white reflectors every so often so those are the best to use. I thought I posted a video of doing a coast down testing on here a few years ago but I searched and can't find it.

I am sure a belly pan would be much better than the back bumper the way it is now, but this was quick and easy and slightly better than stock. If I wanted to put the time and effort into it I could put a belly pan on it but for now this car is good enough till I get some mileage numbers out of it. I will probably fix the front bumper a bit more then drive it for a few weeks and see if I can get some mileage numbers that are good or at least better than I was getting.

I was just going to ask... whose Volt is that!

And for clarification, if you started modding it, it would quickly go on the front page. :)

I knew your PHEV Metro XFi convertible project was a gateway drug...

Here's a drawing of the "optimum nose":

Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - aerohead's Album: Book illustrations - Picture

Optimum nose
 

Here is a link to an image of early use of the low stagnation point 'optimum' nose,by Geoffrey de Havilland's Airco D.H.2,of 1915.
http://houseofqueeg.files.wordpress....h2-04-1200.jpg

That dotted line looks a lot like my Superbeetle. :thumbup:

No, it looks like a lady that shall remain un-named.

And the next one up is a dead ringer for a Ghia!

Parachute effect!
http://i146.photobucket.com/albums/r...ps56f390ee.jpg

http://houseofqueeg.files.wordpress....h2-04-1200.jpg

This is all that I know how to do.

I tried heating and folding under the bottom couple of inches of the bumper. It worked ok but it was really lumpy since I was just doing it by hand. I took it for a quick spin and the car seemed more neutral but maybe a slight bit more downforce than stock on the front end. That is probably about right I figure so I put it back in the garage to try and make it look less ugly.

http://i1288.photobucket.com/albums/...psc279953d.jpg

The easiest thing to do since the curve was basically ok was just cut the bottom off and put a strip across the bottom. I used a bit of heat to form up the joint a bit to make it look nicer.

http://i1288.photobucket.com/albums/...ps1ac0651d.jpg http://i1288.photobucket.com/albums/...pse8543373.jpg

I also used a strip of bumper material to make an air deflector under the radiator.

http://i1288.photobucket.com/albums/...ps1aca27e1.jpg

Now after a quick drive the car seems to drive about right and the fan did not come on at all so it should be getting enough airflow. I will get a picture of it on the ground tomorrow in the daylight. But I did notice when it was parked beside the volt that I have more or less copied the exact profile of the volt. The bumper and hatch angles are almost identical. :cool:

Oh dear that underbody is even more dreadful than on my car. Bellypan it! :D