S13 hood design

[speed_demon]

I am looking into some common hood design cues and trying to get a rough idea of how I will make my hood. I intend to use vacuum bagged fiberglass if I can manage, and my goal here is to make the hood as light as possible.

Now my original thought was to duplicate the stock hood only with a large mesh vented opening in the center, reducing lift and weight at the same time. I would add bracing and reinforcement where necessary. I am also using hood pins, and I am considering using a lift off style with four hood pins.

I am thinking of something very close to this, only larger and closer to the center of the hood.

http://www.kstech.biz/catalog/0203%20Scoop%20Delete%2001%20004.jpg

This is strictly my weekend warrior, not a daily so I am not too concerned over rain or snow.

Any adjustments you think might help? Any other ideas?

[spent]

I would really try and figure out a way to use hinges on the rear. 4 pins can be a pain in the ass. I ended up going back and added hinges on my homemade fiberglass hood. I drilled out the stock hinges and added bolts but at some point, I'll use clevis pins in the hinge so the hood still would be easily removeable if need be, but if I just need to open the hood for a minute at event, I dont have to spend the time getting the hood off by myself, then putting it on the roof, then having to line up the pins when I put if back on again...

[speed_demon]

Using hinges on the rear is no problem at all. I suggested going with four pins for further stability.

Honestly I don't think a light hood that is held down well with two well secured pins should be going anywhere on it's own.

[Matt93SE]

Depends on how light you make the hood. I've seen some that need 4 pins just along the front to hold things together, and then another two just over the wheel wells to keep it from buckling.
yeah, it's a light hood. :)

[spent]

Expanding foam makes for a good structure material on the underside. You can web it out similar to the stock hood structure then glass over it.

[Matt93SE]

small PVC pipe and wood dowel rods also do that job reasonably well.

[speed_demon]

Any reasons why using a foam or honeycomb core for structural stability is not a good idea?

[Matt93SE]

Two layers of glass (to hold the honeycomb together) is heavier than making a few small ribs to brace one layer of glass, but as long as it can handle the engine heat, there's nothing wrong with it.
then again, if you were using a honeycomb, you wouldn't need but a thin layer of glass on both sides of the honeycomb.. up to you.

[speed_demon]

Hmm, I see what you mean. So Wood dowels and small PVC pipe work decently for support beams? Is there any specific orientation that seems to work well?

Also, what type of fiberglass material do you recommend?