I used the same white styrofoam that is used when protecting items in boxes but first I needed to figure out the shape and cardboard worked well for that.
As you can see, I'm still utilizing the bottom part of the scoop that holds the filter and I'm just replacing the top part. Once I had the basic shapes figured out, I simply traced them onto the styrofoam.
Styrofoam is really a pain to work with because little pieces of it go everywhere and static electricity seems to help stick them to everything but again, this is all about getting it done quickly. I used a REALLY sharp knife to cut big chunks away and I have a small styrofoam cutter which is basically just a wire that is heated by shorting out a battery. You can't get much precision with either one of them so I then used a coarse file and finally sand paper to get it relatively smooth. Here is a pic of the scoop before I removed some of the air-inlet material. Btw, I removed the inlet material with a dremel. As you can see, the opening ended up being round rather than oval. That just kind of happened as I was sculpting it. :)
Another drawback (yet also a benefit as you will see later) of styrofoam is that fiberglass resin will disolve it. So, in order to prevent that from happening it needs to be covered with packing tape. Here is a pic of it covered in packing tape.
I could then fiberglass over it but before I did I covered it with mold release wax. I also cut a bunch of small strips of fiberglass cloth and matt. I initially used a very light cloth that is able to follow the countours very easily. I applied a couple of layers of that and then I applied the matt and then another layer of cloth that was a little heavier than the light stuff I initially used. I also tinted the resin with a black pigment.
And here is the bottom of the scoop after the resin hardened and I removed it from the aluminum and after I removed the exposed packing tape.
I obviously haven't worried about any negative countours which wouldn't be acceptable if I was making a mold and this is because the styrofoam is easily disssolved with laquer thinner (just like fiberglass resin). And you don't need very much laquer thinner either! Here is how it looks after I poured a few ounces of laquer thinner over the styrofoam.
Once the styrofoam is dissolved then the tape and clay can be pulled away from the fiberglass so that all that is left is trimming. Here it is after the trimming and removal of any fiberglass "needles"
Here is a pic of the two scoops together with the new one on the right. You can see that the scoop sits higher on the car which was the main thing that I wanted to change.
I ran the car at VIR with this new scoop but I really didn't have any time to pay attention to see if it was working better or worse than the original scoop. I finally found some time to look at the pressure readings from the Manifold Air Pressure (MAP) sensor for the two scoops and the old scoop actually had better readings. So I probably didn't go in the right direction when I made this new scoop but that is ok because it didn't take me very long and knowing that it doesn't work as well is still good information. I'm actually in the process of making a third scoop now which will have a bigger opening than either one of the scoops above and will be about the same height as the scoop on the right. I'm using the same process as above. We will see if that one works better!
