Cheap carbon fiber hoods are almost as heavy as stock
 

Any time I remove components from the Insight, I weigh them. The stock hood, which is aluminium, weighs 9kg/20lbs. Being curious about the potential for weight savings with a composite hood, I looked up how much a riceboy carbon fiber hood weighs. Your run of the mill $600 CF hood for a Civic weighs 18lbs. So you probably save 6lbs versus aluminium. That's pretty unimpressive for $600. I'm sure the savings are even less for replacing plastic panels with carbon fiber.

However, I might be able to make my own carbon fiber hood for around $100 in materials. A hood-sized sheet of fiberglass cloth weighs 1lb per layer, and CF is lighter. Of course you'd have to add resin, and bolt on "features" like hinges, latch, and washer nozzles, but I couldn't picture it coming in over 7lbs.

The lightest carbon fiber hoods are dry carbon, where they use vacuum bagging to suck out the excess resin, and tend to weigh in the neighborhood of 7-10lbs. If you could do that it would be impressive weight loss!

Any quality fiberglass part will be vacuum bagged when its created.

to give an idea of common steel in contrast, I just got shipped a 16.9 pound sheet of 18 guage with 4ft by 25 inch dimensions. I can only assume the hood is attractive to be lightweight.

I tend to go the other direction...the car even has strut braces by factory. Taking steel away is bad news. I can get away with aluminum in some places...

I'd like to know how this stuff works, I do not know many that go the expensive route.

6 lbs versus aluminium, but what versus steel? Never actually weighed a hood, but the Insight's aluminium hood feels like less than half the weight of a similar-sized steel one.

The cheap carbon fiber hoods are not normally 100% carbon fiber, some of them don't even have any carbon fiber but dyed fiber glass or dyed pollyester cloth.
Other cheap carbon fiber hoods have a plastic, metal or fiber glass core, very few of them have stress points that crack or fold if you do get in a head on collision, I like metal hoods because they are designed to fold instead of cutting my head off.

What Ryland said is true. Almost without a doubt the hood has the look of carbon fiber only. They either fake it with dyed fiberglass weave or they lay one lamina of carbon fiber fabric for the look and back it up with layers of glass fiber reinforced polymer.

S-Glass (a good glass fiber) has a density of 2.49g/cm^3, and a modulus of 86GPa where T300 (a lower end carbon fiber) has a density of 1.76g/cm^3 and and modulus of 230GPa. Just by switching to carbon fibers the hood gains several times the strength to weight ratio (Tensile properties are technically worse, but a hood is unlikely to fail in tension, it just needs to hold up to the wind under bending). Then there's the resin, which is a great percentage of the weight in a cheap layup and a small percentage of the weight in a high tech, vacuum bagged, oven cured, prepreg setup.

Note the need to have a vacuum in your oven and also notice only formula one, bikes, tennis rackets, and the newest airplanes are switching to carbon fiber instead of aluminum? ;)

To point out one more thing, a crumple point for safety in a collision has to be designed whether or not the hood is steel or fiber reinforced polymer. If you buy a crappy aftermarket aluminum or steel hood you're probably just as bad off as buying the fiberglass one, in my opinion.

To back you up, "every" (all 4 that I've had my hands on) MKIV Supra Carbon fiber hod that I have weighed comes in 3~5 lbs heavier than stock.

You mentioned that when you took it off it weighed 9 kg/20 lb. Was that for the hood alone without the hinges or latch?

That's a point that many, including me, have always neglected.

Just hope you never crash with a carbon or fiberglass hood, carbon especially, they dont bend when you hit a person, they crack and break into nice sharp edged pieces. They are illegal in Australia for this reason.

I have just taken the bonnet off my Honda Insight G1 and weighed it (aluminium part only i.e. excluding hinges, heat/noise shield, rubber seal, windscreen spray nozzles and tubes, bonnet stay, bolts & lower catch mechanism). I got 6.0 kg (13.2 lb) exactly.

I agree with Red Lions comments regarding the type of weight that would be possible from a CFRP resin infused solution (~7 to 10 lb).

Thus, as Honda did such a good job with the Insight's bonnet, there is not much to get even from a well made CFRP version - won't stop the brave from trying though...

The point has been made, so I was Thanking instead of posting it, but to add a personal experience, I have NEVER found an all carbon fiber hood.

I also notice they never post the weight. All of the "carbon fiber" hoods I have searched have said in small print that they are fiberglass, with carbon fiber exterior or print added. This brought me to confusion if any really existed, or if a standard cf part was mixed with fiber glass.

I tend not to research awesome technology if it's possible for me to do something like, say, buy carbon fiber and make a hood...lol

Just adding what little I know on the topic.

The light weight hoods are typically ill equipped to deal with the stress of hinges and latches, which is why hood pins are used (be it completely removable or just one end pinned at the corners).

I have seen photos of air cooled Porsche's on the track, the hood billowing upward and bowing while almost being sucked off. Not for the street, will leak like silly if it rains.

Done (9.6 lb):
CFRP Bonnet (Hood) - Insight Central: Honda Insight Forum

I'm confused you say the stock hood is 20lbs but that a cheap cf hood is 18lbs but that it's a 6lbs difference. Where are the other 4lbs?:confused:

Also how are you going to find enough fiberglass for a hood for less than $100? That is an incredible deal!