I found a video clip that reveals alot about the webshooters.
http://www.youtube.com/watch?v=i7WRlxrlM7k 5:41 - 6:12
It reveals the size of cartridges, the cartridge replacement system, the web fluid, and the properties of the fluid.
Okay, I just did a quick bit of math using this clip.
Given peter's height is: 5'10"
(height of the cell and radius) 1.8X= 10'5" 65in
(the tiles from door to wall) 3x units = 17'6" 210 inch
cartridge: 4x2x1/2
The surface area of the cell is about 27851.8 inches squared. This would be assuming the wall of webbing is around one inch thick which could be stretching it a bit (no pun intended) leading to 27851.8 inches cubed
The cartridge has a volume of 4 inches cubed (including the extra plating to hold pressure).
This means that ONE cartridge should hold 27851.8 inches cubed of material inside of it. This must mean that peter must have
1.)compressed a large amount of fluid.
2.) added a strong surfactant.
The fluid expanded by a multiplicative factor of around 7000.
0.o I don't know how he does it. My best guess is that he uses a high expansion foam and compresses the fluid to about a 1/7 (1/10 for good measure) to 1/35 of it's original size, but filling the same space in the cartridge. That should give it a LARGE amount of pressure, and would support the turbine hypothsis assuming that the fluid by itself was way stronger than steel and highly elastic.