caddyboy84

I've seen the "BIG-MOUTH" air-dam for the C4 and liked it, but I'll be dammed if I'll pay someone almost $170 for a bent-up piece of sheet metal I can make myself. Today I made the template and it came out perfect, now I'm gonna transfer the Idea to metal. I've been kicking around some Ideas of what to make it out of, polished stainless (to match my wheels), brushed aluminum, sheetmetal painted matte black, or a rigid black plastic moulded into place. I've read that the cooling advantages are very positive.....And it looks pretty DAM cool, pardon the pun.

92ragtop

I would go with sheet metal. That way, if it gets banged up a bit, you can always repair it. Not so with plastic.

Also, I'd go with flat black, unless you want people to really notice it.

mcm95403

on both points.

ChasD

I have a sheet of aluminum already in my garage for just this purpose. Cannot recall exact thickness. I plan to do the same...make a template and transfer to the sheet. Cost me maybe $20 at a sheet metal specialty place in Tampa. I figure I can rivet it to the frame protectors and if it gets banged up...I just get more sheet. I am contemplating a center rib for more rigidity. You should post some pics of your process.

dogfish246

Can you intergrate a splitter into it? That would help with aerodynamics as well

caddyboy84

Thanks for all the input, I will put pics up when I'm done. The template was made from a piece of styrofoam sanwitched between two pieces of oaktag (got at the craft store $3.00) and was 1/8" thick. The opening rail to rail is 29 3/4" wide, I cut a piece slightly longer than that length (so it holds in place by itself) and chose 7" wide, then slid it into place and then lifted it up & down untill I found the angle I liked, and it stood there on it's own from being slightly wedged. The next thing I did was start cutting the triangles for the ends (trial and error) untill I found one that fit snug ( you only have to make one because the other one will be an inverted mirror of the one you already made). I then took the three pieces I made and laid them end to end in the proper order (triangle-long middle section-triangle) and traced that form onto metal. The next thing to do (when I go back to work Monday) is use the sheetmetal-break to make the two bends on each end keeping the middle section at 29 3/4" and your done and it's as nice as factory made. You can use this method to fabricate the air-dam out of any material you'd like. I'm an HVAC mechanic by trade.

pologreen1

Others have done this before too.

caddyboy84

I just added a picture of my template to "My Garage" photo's. Notice how the corners don't go all the way to the end, that allows the bottom piece to tuck under the back of the exsisting dam in the rear. you can do this at any intake angle you'd like.

caddyboy84

leesvet has done this, he got in touch with me and ran me through how he did it and I DO remember seeing this in the forum when he did it. I remember seeing pictures of his and it came out really good, although he did his a little differently It took me 5 minutes to make this template and it'll probably take that long to make the metal dam itself, so if you want one and like it JUST DO ITit's pretty easy. Screw paying almost 2 bananas for something thats worth about $15, no offense "BIG MOUTH", but times are "RUFF!!

caddyboy84

I'm a pretty obsessive guy and the type of person who can be kept awake by the littlest things, at least until I feel as though it's been taken as far as I can. Last night while I was thinking about this DAM project I realized that it would be a good Idea to extend the outter edge about 1/2" past the side braces, so I can than give it a rolled edge for strength. I think without a rolled edge the air pressure might have it start to bow a little up & down at 100mph, so with the roll and the rear extension that tucks under the rear, it should be rock solid. I wonder if I'll feel any drag or lift at high speed, well we'll have to wait and see. If you don't hear back from me about this, consider that me having felt lift. I think I might create some nice frontal downforce if this thing is rigid enough.

caddyboy84

A rolled edge, thats the ticket Then after it's made, clamp it in place and mark the inside braces for 2 holes on each side (2 so it don't pivot) then remove it and drill the holes. Put it back and mark the frame, then drill those holes. Now mount it I wouldn't use rivits yet, I'm gonna check for driveway clearance first, because mine is a little bigger then "The Big Mouth" and has more of a downward angle. Once I get it right, then I agree with rivits, rivits look like it means buisiness..

kimmer

I made mine out of sheet metal because it is forgiving and be bent back in place.

caddyboy84

Did you have clearance problems? Was there a noticeble cooling advantage and did you feel any difference in the drag or downforce?

leesvet

After doing mine and experimenting with all sort of scoop length and angles, I can tell you that the further forwad it sticks out the more air it catches and sends into the box, HOWEVER, if the bottom plate/scoop is not supported well, it CAN fold up and block airflow at high speed. That is why I use a steep angle downward on my extended scoop. Its supported on the sides at the skid rails, held by L brackets (slotted and adjustable) so the scoop angle can be raised or lowered. Currently raised because I recently moved where I now have to drive down a dirt road to get home....

anyway, my scoop is at least 4" forward of the skid rails, so it does act as a splitter at high speed by preventing air from going under and forcing the max amount upward where it is trapped by the side panels and forced to the radiator.

Performance:
I have a hi-flow water pump and big radiator on a built engine that likes to get hot real quick...
I can idle and see the temp climb pretty quick to 220 and even tapping the throttle to give the pump some rpm is not enough to help very much. BUT, as soon as I start moving over 10-15mph there is a huge increase in fresh air thats sent to the heat exchanger and the temps drop and stabilize very rapidly. I can be back at 189-191 in a matter of a minute or 2. Conclusion: the DIY BigMouth works. The more you trap the air (box it in) and direct it and focus it or aim it, the more efficient the design. The more of a scoop you make to get the max possible airflow, there more potential for damage to the scoop from grounding, which is why I went with plastics since they act like a wear part and simply grind a mm off the edge when it scrapes...Change it once every couple yrs when doing major front end maint cleaning. use the old bottom plate/scoop as the template for the new and cut it out and screw it down and go have fun !

This design FAR exceeds any of the fiber-glass air-dams or plastic production models that are sold in catalogs. The glass dams were inefficient and were brutally damaged by road debris or grounding out. I had one that had been repaired so may times that there was almost NONE of the original fiber glass left in the thing....The ABS plastics that I use today are far more forgiving when you are stuck with running over a tire casing that gets thrown at you and the choice is hit that or the minivan in the next lane...BTW, the plastics are min 1/4" thick or slightly more. Very stiff and durable.

As far as my dimensions....my side panels on the skid rails hang down to 3" off the ground and the scoop comes down to about 2" off the ground while parked. Its so low that I often have to "back-out" of some places so the scoop does not get caught on edges or bumps/dips in driveways or entrances.

That leading edge lowers itself as air pressure builds from speed increases and bends it down even more as speed increases. Its trial & error to find the max length that your car can handle without constant dragging the leading edge at high speed. Makes a hellluva noise scraping the concrete at 100+ mph. I also experimented with a replacable leading edge that was designed to be a wear part...a strip about 3" deep X the width of the scoop leading edge. That way I could change that leading edge in minutes when it wore out instead of having to change the whole bottom plate/scoop.

caddyboy84

I was kicking around some ideas, I thought of making it like a tunnel (or duct) and bringing it all the way to the front of the car under the lisense plate with the same curve as the header and putting a grill on it, like a newer Vette's grill. I think that would look sick

leesvet

It DOES...!

its just a matter of gorund clearance and finding that "sweet spot" where you don't scrape yet get the max scoop effect. Mine probably sticks out to maybe 4-5" behind the license plate...but its down at a pretty steep angle as it curves downward from the lower radiator shroud bottom.
I was toying with the idea of installing some kind of limiting cable or bracket so the leading edge could not go too far down...Like maybe small stainless cable at each corner of the scoop to stop it from going so far down at high speed...or a bar that would allow it to slide to a certain point then stop. That 10 cyl car that dodge made had a mechanical splitter/air dam that dipped down as speed increased and raised as the car slowed...Thats kinda what I'm working toward. It was controlled mechanically so it was not subject to control by the aerodynamic forces that operate mine as it is. Mine is sort of "automated" which is fine, except for some situations where I may not want the extra air or I need more ground clearance. Like now, its pulled up and held up by the side panel brackets. I'd like to be able to lower it once I get to flat roads without laying in the street...
I just want another switch or gadget to install somewhere !

cv67

Its called The Car Disease

Thinking about making something similar for mine (non vette)
Id think the air, at speed would want to pull downward on the piece so it should be strong. Rather replace some bolts than make another piece such as is the intention of the BMAD piece.

HAd them on both my C4s and thought it was worth it. Bought 2 blems for 100 ea . Worth it to me at the time.
Nothign wrong with getting creative though.

caddyboy84

OH MY GOD!!IT'S MADNESS I SAY!!!SOMEONE STOP US!!! Thank God I'm single, my dining room table is covered with car parts When I was restoring my Benz, I had parts all over my bed room, I had to make sure my new chrome was safe. I actually put my chrome bumpers together on my bed (No scratches), it was the prettiest thing on my bed in a long time..........JESUS CHRIST!!!SOMEONE STOP ME!!! I've gone MAD!!

caddyboy84

People ask me about who I'm currently dating and I tell them "She's Plastic". "So, She's a Phony"? They ask.........No, she's a CORVETTE!!

383vett

Ok guys, we really need some pictures...