Air Dam and Front Undertray

[Bill in Houston]

This whole explanation is way too long. Just look at the pictures and you will figure it out on your own. It’s not rocket science. If you have any questions about what I did, the written explanation below might be helpful.
http://www.gassavers.org/attachment.php?attachmentid=278&stc=1&d=1174673033
The actual materials used aren’t particularly relevant. I think you could use whatever seemed right to you, and get an equal or better result.
Basically you need to figure out three things:
Where exactly do I want the air dam?
How will I attach it to the car?
What materials can I find that meet my requirements for strength, cost, durability, and aesthetics?

Where do I want the air dam?
I wanted the air dam to be close to the front edge of the front bumper for maximum effectiveness. I had originally thought about installing it a little farther back where it wouldn’t be visible, but as I thought about it, I decided I could come up with one closer to the front edge that would work better and would look okay.

How will I attach it to the car?
The Element has six fasteners on the front underside of its front bumper. Four are bolts that hold all the various plastic panels up there together. Two are “push rivets” or whatever you call those fasteners with the center that you pop up. The push rivets are secured to a couple of metal pieces that underlie the plastics exterior. These six fasteners seemed to be a good way to attach the air dam.

What materials can I find that meet my requirements for strength, cost, durability, and aesthetics?
I don’t have access to any exotic or exciting materials, so I am limited to whatever I can round up on my own. I am painfully frugal, so I wasn’t going to buy any super-cool textured plastic panels or nifty aluminum extrusions. And my finished product had to look good enough to pass my family’s approval. I eventually decided that the landscape edging would be a good flexible exterior covering. I considered aluminum flashing for the exterior, but decided it didn’t have the look I wanted, and would be too hard to shape smoothly. The aluminum binder strip was something I ran across while wandering around Lowe’s looking for suitable materials to build the underpinnings of the dam. Coroplast is a material that I have always thought was cool because it is light, cheap, weather resistant, stiff for its weight, etc, etc. In my internet journeys I ran across people using it to make all sorts of aerodynamic mods to their cars, so I figured it would be a great choice. Gorilla Glue is a product I had heard of but never used. It is a urethane glue that is about the consistency of honey and it cures in about 3 hours, expanding while it cures. It is pretty weird stuff, but it does the job in a way that would be difficult or impossible with other adhesives.

[Bill in Houston]

I started out by deciding where I wanted the dam to be located relative to the six mounting points, and using that concept to cook up the dimensions of the mounting brackets. I made six L-shaped brackets out of aluminum binder strip. The four outboard brackets are secured with the original bolts in their original holes. For the two inboard brackets, I removed the push-rivets securing the bottom of the center piece of the bumper. I then put a speed nut (also called a U-nut or J-nut) on each of the two metal brackets that underlie the center piece. When I reattached the center piece, I used bolts in those two holes instead of the original push-rivets and secured the two inboard brackets with the bolts.

Having used the brackets to determine the general shape of the dam, I started working on the aluminum frame of the dam. I bent two of the pieces of the carpet binder strip into a shape that fit the curvature of the front of the car, and that lined up with the locations of the six brackets. One piece of the binder strip was to go along the top edge of the dam and provide strength for the eventual mounting of the dam. The other piece was to go near the bottom of the dam to prevent deformation of the dam at speed and also to provide a place to mount some internal bracing and the edges of the undertray.
This photo of the inside of the installed air dam shows the following: 1-two of the brackets, the one on the R is secured to the speed nut and the one on the L is held by the OEM bolt 2- the upper and lower binder strips 3- the foamed-out Gorilla Glue
http://www.gassavers.org/attachment.php?attachmentid=279&stc=1&d=1174673222

To prepare the edging, I had to cut off some of the ribs that were originally intended to hold the edging in the ground, and then give the edging a uniform surface. I cut off the ribs with a utility knife. I used 100-grit sandpaper to remove the remainders of the ribs. On the side of the edging that was to become the exterior, I used 600-grit paper and then a scotchbrite scuff pad in a linear motion to give the plastic a uniform satin finish. On the interior side, I just roughed it all up with the 100-grit for better glue adhesion.

So at this point I had two pieces of binder strip bent to shape, and edging that was ready to attach. I applied the Gorilla Glue to the interior side of the edging. I then used a multitude of clamps to clamp the edging to one of the pieces of the aluminum binder strip. I used the other pre-bent strip on the outside of the dam to help distribute the clamping force. Basically, the edging was sandwiched between the two pieces of binder strip, but was only being glued to one of them. I let the glue set/dry/cure overnight.

Since the piece of binder strip along the bottom of the dam was going to be where I mounted the different supports for the internal bracing and for the undertray, I put carriage bolts into the predrilled holes in the strip and used a nut and washer to umm, squish the square part of the carriage bolt into the round hole in the strip. I then glued this second binder strip to the edging. This was a little different than gluing the first strip on. For the first strip, the edging was nice and flat and had a simple curve to it. For this second strip though, I was trying to glue it to a place on the edging that had a complex curve. Using clamps would have made weird flat spots. So, I taped the strip onto the edging in the place it should go, and poured glue into the space between the edging and the strip. It took a lot of glue. This was an instance where the foaming of the glue was useful to help fill up the space between the edging and the binder strip. I let the glue set overnight.

[Bill in Houston]

At this point I did a test fit of the air dam. You will notice in the photo that the dam is not bent to its final shape. The front is shaped already, but I had not bent it rearward to complete the shaping. I had previously confirmed with sample pieces of edging and binder strip that I would be able to bend the glued pieces without causing the edging to peel off the binder strip. I put the piece on the car and held it in place with some clamps. Once I had it centered, I drilled holes thru the dam and the brackets, and put carriage bolts through the holes. This is a place where someone smarter than me can come up with a tidier way to do the attachment. I think the carriage bolts look okay. If they were not visible, though, the air dam would look more like a factory piece of equipment, rather than something a guy built in his garage. Oh well.
The first photo shows the test fitting. The second photo shows the heads of the carriage bolts in the final installation.
http://www.gassavers.org/attachment.php?attachmentid=280&stc=1&d=1174673353
http://www.gassavers.org/attachment.php?attachmentid=281&stc=1&d=1174673387

[Bill in Houston]

Once I had the air dam bolted on to the front six attachment points, I marked the spot for the small radius bend at the outside corner of the vehicle, and then the sharp 90 degree bend where the dam turns and goes in front of the tire and basically becomes part of the inside of the wheel well. I removed the dam and made the bends. If I had it all to do over again, I would have done things differently. I would have made all of the bends in the binder strip beforehand, and then glued the edging to it. That probably would have had its own headaches, but I think it might have given a slightly better result.
The photo below shows the two places where I had to bend the air dam on each side. The undesirable effect of looking through and seeing the ground is eliminated once the undertray is in place.
http://www.gassavers.org/attachment.php?attachmentid=282&stc=1&d=1174673475

[Bill in Houston]

At this point I had the air dam in its final shape, attached to the vehicle. It might have worked out okay to just mount it to the vehicle and call it done, but I wanted to do a little more to make it more sturdy and more functional. So I added the internal bracing and the undertray. The bracing is made from the same binder strip material as the rest of the dam, and the undertray is made of Coroplast.

I started on the bracing by making little L-brackets for all of the carriage bolts that were in the binder strip on the lower edge of the dam, and attaching the brackets to the dam. On the ends of the air dam, the bracing goes from the inner front of the dam to the inner rear part that faces the wheel well. This helps give some strength to the rear part, which is otherwise not secured to anything and would likely flutter some due to air currents in the wheel well. In the center of the air dam, the bracing goes straight back toward the rear of the body, and then is bent in an S so it can be secured to the underside of the vehicle. For the rear mounting point I located a couple of holes that some of the factory undertray parts were attached to, removed the factory push-rivets, and put in carriage bolts. Having this brace go straight back and then make the S-curve gave the undertray a longer surface to attach to and be supported by.
First photo shows the little L-brackets and the carriage bolt in the lower binder strip. Second shows the S-curve and the attachment point. Third shows the flat surface to attach the undertray to, the bracing on the end of the air dam, and my knee. :)
http://www.gassavers.org/attachment.php?attachmentid=283&stc=1&d=1174673711
http://www.gassavers.org/attachment.php?attachmentid=284&stc=1&d=1174673767
http://www.gassavers.org/attachment.php?attachmentid=285&stc=1&d=1174673816

[jwxr7]

that actually looks pretty good :thumbup: . someday i will put some effort into the aesthetics of my aero mods :o .

[Bill in Houston]

For the undertray, I first made a pattern by gluing together a few pieces of foam-core board, cutting it to shape, drilling holes through it and the underlying bracing or brackets, and securing it with nylon push-rivets. There was no rain in the forecast, so I used this foam-core undertray for several days before making the final one out of Coroplast. I made some vortex generators (VGs) out of aluminum flashing and glued them to the Coroplast with Gorilla Glue. Of course, the Gorilla Glue foams and squirts out, so I had to sand some places flush after the glue set. The VGs are about an inch tall and are mounted at a 15 degree angle from the centerline of the vehicle. The height and the angle were chosen based on the VG work that the Mitsubishi Evo engineers did. The idea of the vortex generators is to virtually extend the length of the undertray to control airflow under the body for a little farther. The undertray by itself would have controlled the airflow over the front suspension subframe. I am hoping that the VGs will extend this control back a little farther to where the exhaust and fuel tank protrude downward. The efficacy of the VGs is surely small and unproveable, but I like them and they are fun to talk about, so I put them on. HA! Anyway, the trailing edge of the undertray is about as far back as the oil drain plug, and is about 2 inches lower. I think that this amount of space will allow plenty of airflow beneath the engine and don’t expect any cooling problems. Plus, the air dam should actually force some additional air up and into the lower grille opening, again allowing for plenty of cooling. I like the undertray a lot because it is the kind of detail that could be skipped and hardly anyone would have the snap to even ask about it, but people in the know understand that it is a very important part of making a functional air dam versus a cosmetic one.
The photos below show (1) the unmounted undertray, (2) the mounted undertray and the nylon push-rivets, and (3) a view toward the rear of the vehicle showing how the undertray should help deflect a lot of air away from the rough underside.
http://www.gassavers.org/attachment.php?attachmentid=286&stc=1&d=1174673929
http://www.gassavers.org/attachment.php?attachmentid=287&stc=1&d=1174673975
http://www.gassavers.org/attachment.php?attachmentid=288&stc=1&d=1174674017

[Bill in Houston]

Here is the finished product on my dirty Element. I like how it looks, and my 12-year-old son agrees. It is still high enough off the ground to clear MOST curbs. I will need to be careful not to damage it. I might eventually paint it, but I think the color is fine for now.
http://www.gassavers.org/attachment.php?attachmentid=278&stc=1&d=1174673033
http://www.gassavers.org/attachment.php?attachmentid=289&stc=1&d=1174674124
I do not have any gas mileage data yet to determine whether this was a good fuel efficiency mod or not. For what it’s worth, all of the placebo effects seem to be in place.  I am easily able to imagine that my coast-down times are longer and that the vehicle is more stable in crosswinds.  Also, something I didn’t expect is that the vehicle seems quieter inside, which is nice. Over time I will be able to collect data, do some analysis, and see if I have really made an improvement or not. And if it really does become a science project for one of my kids (or if I get bored one non-windy weekend), I will do some real A-B-A coast-down tests to see if I can measure a Cd improvement or not.

[Bill in Houston]

that actually looks pretty good :thumbup: . someday i will put some effort into the aesthetics of my aero mods :o .
Thanks!

[zpiloto]

Nice craftmanship. How is the Belly tray attached? Can you remove the Airdam and still have the Belly tray? Just something else you can test for FE, with and without airdam. Do you notice any quicker warmup times?

Nice Job.

[Bill in Houston]

Nice craftmanship. How is the Belly tray attached? Can you remove the Airdam and still have the Belly tray? Just something else you can test for FE, with and without airdam. Do you notice any quicker warmup times?

Nice Job.
Thanks! I appreciate the compliments. The tray is attached to the dam bracing only, and not separately to the car. I could test no dam vs dam alone vs dam plus tray, but not tray alone.

Another placebo effect I forget to mention was the perceived faster warmup times.:) No, sorry, I am pretty much un-instrumented when it comes to serious temperature readings. I don't know if it would lead to faster warmup or not. Most of the stock openings are still open, and have a couple of inches of clearance between them and the tray. I would not expect a faster warmup, at least not with the amount of grille opening I still have.

[zpiloto]

Thanks! I appreciate the compliments. The tray is attached to the dam bracing only, and not separately to the car. I could test no dam vs dam alone vs dam plus tray, but not tray alone.

Another placebo effect I forget to mention was the perceived faster warmup times.:) No, sorry, I am pretty much un-instrumented when it comes to serious temperature readings. I don't know if it would lead to faster warmup or not. Most of the stock openings are still open, and have a couple of inches of clearance between them and the tray. I would not expect a faster warmup, at least not with the amount of grille opening I still have.

Is a grill block next? That's very easy. I run one year around with no overheating problems although Hondas seem to be a little touchy in that area.

[SVOboy]

Hondas are touchy about overheating? I haven't heard anything about it!

[zpiloto]

Hondas are touchy about overheating? I haven't heard anything about it!

Well I guess I miss spoke. But it seems that most that had a honda on the site when they put the grill block on complained about it overheating.

[Bill in Houston]

Is a grill block next? That's very easy. I run one year around with no overheating problems although Hondas seem to be a little touchy in that area.
I was going to ask about that. Is it better to block the lower or the upper? My upper is already blocked. I'd be afraid to block both, but might be able to get away with it.

[SVOboy]

Well I guess I miss spoke. But it seems that most that had a honda on the site when they put the grill block on complained about it overheating.
Really? How odd. I know that my radiator is quite too big for my engine, *shrug*

[zpiloto]

I was going to ask about that. Is it better to block the lower or the upper? My upper is already blocked. I'd be afraid to block both, but might be able to get away with it.

I've blocked both. Initially just make it so that you can easily remove it if the car overheats. Or you can cut a few 4X4 holes in it till you get it where you want it. If you use the search feature at the top of the page and type in Grill Block you can look at what other folks have done.

[MetroMPG]

Wow. Nice work!

For what it’s worth, all of the placebo effects seem to be in place.

I'm happy to read someone who understands this issue and refrains from proclamations of success based on them alone.

That said, I also noticed my car is quieter inside with the undertray, as did krousdb when he did his Del Sol.

And if it really does become a science project for one of my kids (or if I get bored one non-windy weekend), I will do some real A-B-A coast-down tests to see if I can measure a Cd improvement or not.After only seeing around a 2% improvement with my full undertray, I'm also kind of itching to do an A-B-A with a large and a medium-sized air dam, something which will give the nose of my car more of a NASCAR profile.

Impressed.

[cfg83]

Bill -

Thank you for all the work doing the pictures. Just the right size and detail. I'm a wing-nut fan myself, so I like that detail. And the Vortex Generators too!!!!

CarloSW2

[Gary Palmer]

Look's nice. On the grill block, one thing I found on my 89 Honda was that I was able to block the airflow almost to effectively. I also found that it seems to work much better with my 4*4 opening on the side of the radiator where the fan is. I had an opening on the other side and it didn't seem to help very much. I highly recommend it, just monitor the engine temperature and open it up if you have any doubts. A cooler engine beats a cooked engine, any day IMO.

[red91sit]

wow! one of the nicer air dam installations I have seen, Ya'll got me a bit more motivated to work on my car again!

[kps]

Hondas are touchy about overheating? I haven't heard anything about it!

In early winter I put a lower grille block on my Fit, and found that in highway driving the engine temperature increased to the point that the radiator fan ran continuously.

[SVOboy]

Mmm, that's annoying.

[Bill in Houston]

Thanks red91sit. It didn't end up taking THAT much time, and it was spread over a few weeks, so I'm sure you can squeeze in some mod time. :-)

zpiloto and Gary, I'll have to experiment with grille blocks. kps, constant fan running would be a good thing to avoid, huh? :-) I'll be watching out for that.

MetroMPG, I was surprised that the undertray made a difference in the noise level. I'm glad that you confirmed that others have noticed the same. It would actually be easy to add more sound deadening to it. I hope that you get good results with your air dam experiments.

CarloSW2, I'm glad that it was the right level of info for you. Once I got it assembled, I looked at all the wingnuts and thought "what was I thinking?" But it really did make it all go together easier, which is pretty valuable when you're lying on your back under a car.

[Hockey4mnhs]

looks real clean keep up the good work

[psyshack]

My Civic hasn't had over heating issues at all with it engine belly pan. Only thing I can tell it does for me is help to keep the engine compartment cleaner. I cant tell its done a thing for mpg.

[eivad1]

is it the lower u go on the air dam the better and more force on the front end, is there a wing for the 87 crxs on top of the hatch

[red91sit]

Not neccesarily, you go too low, and You increase frontal area causing more aerodynamic drag.

[eivad1]

i tried putting tape on the front end of my crx and with-in a 5 miles period the temperature went up, i had to take off the tape, i do tho havea small 2 inch gap that gets to my radiator eand gets air, but was wondering if i could just make some holes in the front nose panel and re tap up the lower part

[brucepick]

Bill in Houston,
I think you did a great job.

I drive an "89 Volvo with OEM air dam that was standard on those cars but I hope to add an extension downward based on what you showed.

Going off-topic - - -

I put in a grill block this past Friday. Tested a full block the day before, looked like a gain of 1.75% with full block in about 35-40 deg. F temps.

For grill block,
I wanted to leave small openings spread out over grill area rather than one single hole. I used lengths of dark gray foam pipe insulation stuffed between the grill slats. I thought it would not show but it's very visible. Insulation is 3/8" thick; squeeze flat and stuff into slot space. Ended up looking like a decent home-brew job. Don't know yet if I'll need to remove it in hot weather. Probably.

[brelandt]

Not neccesarily, you go too low, and You increase frontal area causing more aerodynamic drag.

Not according to the March 2007 issue of Hot Rod Magazine.
Page 115 article "wind camp" under section, "tech theory" Sub article, "top 5 easy areo mods that almost always works" states this;

"You can usually get 90 percent there just by adding a dam striaght down from the front bumper......we have that big barn door on the front of the car, but keeping air out from under the car both reduces drag and neutralizes lift for solid areo gains....20 counts less drag and 50 less lift. the taller the car sits, the more important the air dam is."

It further states that the benfits of a large air dam outweights the higher frontal area.

Anyhow, Great info on you dam article!!!!!

Looking to do mine soon as well.

[zpiloto]

I agree with red91sit on this. I found it to be true with the mazda 626 anyway. YMMV.

[brelandt]

How tall are we talking about?

If you watch NASCAR which I don't or have ever seen a NASCAR you will see how freaking hugh their dams are as well to how low to the ground they are. The car has a much greater frontal area than any stock version of said car but is much more areo efficent.

Now if you are talking about adding a bumper to ground dam on lets say a 1985 K-Blazer with a 6 inch lift than yes there will be a neg. effect.

[Bill in Houston]

Bill in Houston,
I think you did a great job.

I drive an "89 Volvo with OEM air dam that was standard on those cars but I hope to add an extension downward based on what you showed.
Thanks!

I hope your extension works out well for you. Extending the OEM air dam should be a relatively simple task since your attachment points are all figured out.

Something that I read, and that I believe, is that behind the air dam, you need a smooth surface to get as much drag reduction as possible, so I built the undertray. The undertray also helps take a lot of flex out of the dam too.

Anyway, good luck and keep us posted.

[zpiloto]

How tall are we talking about?

I brought it down to 4 inches off the ground.

Now if you are talking about adding a bumper to ground dam on lets say a 1985 K-Blazer with a 6 inch lift than yes there will be a neg. effect.

According to Hot Rod mag you quoted it would especially be need for the example above.

"You can usually get 90 percent there just by adding a dam striaght down from the front bumper......we have that big barn door on the front of the car, but keeping air out from under the car both reduces drag and neutralizes lift for solid areo gains....20 counts less drag and 50 less lift. the taller the car sits, the more important the air dam is."

Don't know about NASCAR but it didn't work for me but the belly pan sure did. YMMV

[brucepick]

... Something that I read, and that I believe, is that behind the air dam, you need a smooth surface to get as much drag reduction as possible, so I built the undertray. The undertray also helps take a lot of flex out of the dam too...

Thanks Bill,

Hmm. The car has a short OEM belly pan but it starts just under the radiator/ac condenser. In other words, does not continue directly off the bottom rear of the air dam. Pan extends only about 18 inches to front of block. Pretty good considering it's from '89 though.

I could fairly easily put in a panel going across rear bottom of air dam to the front of belly pan. Should give some improvement, right? (When dam's lower extension is built I'd attach to rear bottom of that.)

Is that you have in mind? Of course a full lower pan would be best - but that's more involved; still considering that for when warmer weather gets here.

[Bill in Houston]

I could fairly easily put in a panel going across rear bottom of air dam to the front of belly pan. Should give some improvement, right? (When dam's lower extension is built I'd attach to rear bottom of that.)
Yep, that is what I was talking about. Sounds good to me. A small improvement, maybe, but an inprovement nonetheless.

[brucepick]

[Bill] - Yup.
They're all small improvements and they add up.

Heh-heh, back in the '70's the joke was that this guy said he bought every fuel-economy-improvement doodad and magic fluid he could find. Every one of them claimed to reduce gas consumption by 5 or 10 percent. Eventually he noticed that the tank got more and more full as he drove down the highway....

[Bill in Houston]

:-)

[brelandt]

According to Hot Rod mag you quoted it would especially be need for the example above.

"You can usually get 90 percent there just by adding a dam striaght down from the front bumper......we have that big barn door on the front of the car, but keeping air out from under the car both reduces drag and neutralizes lift for solid areo gains....20 counts less drag and 50 less lift. the taller the car sits, the more important the air dam is."

Don't know about NASCAR but it didn't work for me but the belly pan sure did. YMMV

Belly pan would be the best way of going about it. Unfortunately for me and my pug nosed Sidekick with really low underhangs it's impossible.

The only way for me to keep the air from getting all turbulant and messy is to just block it off from getting there to begin with.

However, I have not done this yet and I may have to lower the truck first. When I do build mine I will make it just low enough to cover all of the hanging parts without lowering the truck.

If this doesn't work, than I will build the dam lower to the ground. Then if need be I will lower the whole truck, but as a last resort.

Also the dam works better if placed even with the front edge of the bumper and not behind it like almost all air dams are.

Anyhow, Good job Bill in Houston!!!!! :D

[Bill in Houston]

Thanks, Brelandt!

[Bill in Houston]

Well, after a month of air dam and front undertray use, it seems that it has not improved my highway mileage. It may have actually lowered it. It definitely does keep the front end more stable at speed. So maybe it is actually causing some downforce, which I would gladly trade for higher mileage.

So here's my question. If I use a manometer and find out that the air pressure above the undertray is higher than the air pressure below, is there something that I can do that would allow me to trade downforce for lower Cd? Like maybe lowering the back edge of the undertray?

I will probably try it no matter what, but just wondered if anyone thought I had a chance of being successful. ;-)

Update:
In mid June I did lower the trailing edge of the undertray a little closer to the ground. It seems to make less downforce now. I assume that this improves my Cd.

Thanks for the input!

[atomicradish]

It looks great especially considering your frugality.

Fortunately for me, I have no need for an airdam. My car is already quite low to the ground.

[Bill in Houston]

For the sake of completeness, this is a link to the coast down testing that I eventually did. Show something like 10% improvement in Cd.

http://www.gassavers.org/showthread.php?t=4419

[fabrio]

i looked your job Bill: very good!

[Bill in Houston]

Thanks!

[fabrio]

you have made a job much cleaning up (professional), and the result of your test is indicative about quality of modification.
I have written a simple excels for to calculate the acceleration or drag: it is necessary to read the GPS NMEA after a procedure equals to Coast-down Test, but at the moment, it is not capable of CD result, but to calculate only complessive resistance (drag+rolling resistence)

[Bill in Houston]

Do a few runs coasting from 65 mph to 60 mph.
Do a few runs coasting from 15 to 10 mph.
Dump the data to Excel. For the high speed runs and the low speed runs, plot speed vs time and draw the best-fit line. From that best fit, figure out what to put into the calculator at http://web.archive.org/web/20040803073229/http://www.race-technology.com/WebPage2/Other/Utilities/Coastdown/CoastDownCalcs.html
That calculator will calculate your Crr and CdA separately.

[fabrio]

yes, the algorithm is simple.
it must calculate the negative acceleration in high speed (that it allows to obtain the sum of all the resistances), after, it must calculate the negative acceleration in slow speed (that it allows to obtain only the rolling resistance)

for last, it is necessary to embezzle the CRR at the total resistance, the result value, it is the aerodynamic drag!

in my excels file, this I have not still implemented it, only, because, I have not still had way to make a test with the car

[johnf36]

I am new here but thought I would help with a source for VG's if you have not found them yet.
http://www.vortekz.com
and here is a picture of the car, I am getting started on side skirts when I found the site.

[gto78]

Hi, I'm new to the site as well. I've been in aviation for 13 years and have education/experience in aerodynamics. My first thought after seeing your undercarriage pan was that I'm jealous and want one badly for my explorer...

My second thought is that it would probably work a Lot better if it had a very slight ramp/spoiler aimed downward toward the ground. I'm trying to picture the airflow if the vehicle was in a wind tunnel, and how you want it to aim down just enough to make the air clear the rear suspension, but not cause any drag. If it aims down too much it will reflect off the ground and probably try to lift the rear of the vehicle or just swirl around.

Excellent job, I hope to have as much luck with mine as you did.

Joe

[MarkM68]

Here's some aero tricks from Hot Rod;

http://www.hotrod.com/techarticles/body/hdrp_0609_aero_tricks_tips/index.html

[lowbridescape]

Dear Bill in Houston

Have you considered putting clear covers over the recessed fog lights? I had noticed on the new retro Ford Mustangs that even though the headlights were recessed to match the old style, there were clear covers over them that smoothed the front of the car. Your sunken fog lights act like air brakes. Aerodynamics 101...forward facing holes that aren't feeding engines = bad.

[quadancer@bellsouth.net]

I love the air dam, very good work! Probably the wrong place for a question, but what about automatic tranny cooling? I know an overheated tranny is a quick kill, and with a radiator block...well...

[red91sit]

Very true, that's why if your temp gauge goes up with your grill block, it's blocking TOO much. Temperature should be regulated via the thermostat. Not just using the fan to limit over heating.. One of my little pet peeves.