I'll stand by my previous statement, and you're just proving my point.

It's easy to make a lighter hood than stock, even with an aluminum hood like my WRX. Aluminum is a little more tricky, but at 14.5 pounds for a stock WRX hood (supposedly, on secondhand information) it's still easier to make a carbon hood lighter than that. A 14.5 pound carbon hood is heavy, and to think that yours is heavier than a stock steel piece is horrifying. The EG hoods I used to make were 8 pounds for the lightweight (but $$) race versions, and 12-13 for the much beefier/cheaper street version (with somewhat similar construction as many of the better commercial units on the market).

Your hood is probably mostly fiberglass, and has a really thick layer of gelcoat, and is overbuilt because it's a carbon copy (wow..that was unintentional) of a steel hood. It's also probably really thick to get any kind of stiffness because it doesn't have a core, and it probably has a thick fiberglass copy of the steel substructure on the back. If you can check at least some of those boxes, your hood is probably a piece of crap.

I've said all of this before, people who don't know anything about composites try to replicate a steel piece out of composites, and it works but is a really long way from good design practice.

 

I would think that people who make a lighter hood wouldn't have rain channels, or even and understand brace to try to achieve a CF hood lighter than my Aluminum? Or are you saying that you or some other person can build a CF hood lighter than my Aluminum with rain channels and an under brace? The Amuse hood they make for my car has no under brace nor rain channels, but it does weigh in at something rediculously like 3lbs. That too me just seems like a sheet of CF to cover my engine bay. If it did weight 3lbs, that's a $1000/lb for this hood.

 

That may be, but anything right from Japan is overpriced anyway. You don't need underbracing, there are better ways to stiffen composites parts, which is what I was saying about not duplicating metal designs out of carbon. Rain channels are very model specific and I'm not going to make any generalizations; I don't even know what car we're talking about here, but I will say that a lot of stuff like that can be bonded or fastened on in similar ways to the OEM parts. I wouldn't count the weight of a rain channel that attaches separately anyway, any fasteners or accessories that will remain are part of the weight of the OEM hood and the aftermarket hood, so they don't really factor into any weight savings. I'm not entirely sure I know what type of rain channels you're talking about though.

There is a middle ground also, a 3 lb $3000 hood is at the extreme minimalist end of the spectrum, a hood weighing 3 times that much would still be lighter than a stock hood, and be much stronger and stiffer than the Amuse piece sounds like if it's properly made. You can make an aluminum fender that was as flimsy as a coke can, but do you really want it on your car??

 

Oh ok.

 

it is exactly that... a piece of carbon over your engine bay....

what fab is sayin composite parts have different tendencies... they distribute weight differently, they absorb impact differently.... and also they have different strength to wieght ratios.... and so on..

if you were to engineer a carbon part..... why would you engineer it like a steel part..... more than likely if you where to reinforce the rails of the hood to support the hinges and reinforce the hood pop..... by usinge a bi directional weave clocking at both hinges with two layers it would create an intersection at the front of the hood. i would then run the last layer at roughly parralel with the front of the vehicle. i feel this would take stress to the hood pop and direct to the rails (sides) and then on to the hinges. i dont think a 3 layer part with its orientation like this would need any more under bracing.... waste or carbon and weight. imo. of course you can calculate this and test this. many factors are now in play fabric weight... strand count and so on.


orientation or clock would look like a capitol V with a dash in it..... -V-


btw fabrik8 i looKed ate those links and was astounded..... i was making carbon parts on 2003 and buying rolls for just over 2100 shipped from china. 100 yards not feet....... damn i wish i stayed in it or had a million bux worth of carbon stashed away.... it would have been the best investment yet. gold doesnt change price like that.

 

Supply can't keep up with demand, that's the problem right now. Hexcel and Toray are both building new carbon plants to try to reduce the shortage, which should stabilize things for a while.

The way I would make a hood: 4 layers of carbon, two on each side of a foam or honeycomb core, making a relief in the core thickness (if necessary) for the valve cover. If you want really stiff, a foam box frame around the outside edges (blended into the core) would really help, and make a convenient place to bond mounting inserts. The EG hoods I did were roughly similar to that, although more minimalist. If you want more impact resistance, another layer or two of carbon or fiberglass would be good, but won't really add much to the overall stiffness unless you add balanced layers to the bottom side also.

 

heres a pic of a front fairing i made back in 2004 for a 90,s something yamaha bike. i made probably about 20 or so till my mould broke.... was a pain in the ass to make without having cuts in my material.... i used west sytems epoxy and vacuum infused them... i just came across this pic and figured id show it off. 2k twill 3 layers.

http://www.geocities.com/dallasb84/carbonfiber.html

 

btw im up for donor parts in the 757 to make moulds. we can talk deals later ive got a dc integra dash waiting to be used. gotta pick it up.

 

Is that purple piece a male mold or is that the stock fairing?

 

it was to original fairing..... i made a female of it. i set them side by side to show a before and after. you can see all the wax and a little bit of sanding i had to do to get rid of the imperfections on the fender. ill never do these parts again as it was a pita to get the carbon to lay right in the mold. i did these parts with infusion. and a clear coat after it was pulled.....