Fiberglass vs CF hood strength
 

I'm getting ready to place an order for a hood, but was wondering what the structural strength difference of Fiberglass vs. Carbon Fiber was, and if it's worth the typically $200 more charge? The hood will be painted either way to match the car, but as far as opening and shutting the hood, wear and tear, etc. Is there a difference in how they will wear? Which will the paint stick to best?

For your usage, you will never notice the differance between a quality FB hood and a CF hood. If it's going to be painted, I say get the fiberglass hood. Not worth the extra money.


Paint will adhere to them equally.

Thanks! I don't know much about Fiberglass. My only concern was it cracking and chipping. But for everyday normal street driving that should't be a concern? The hood is a Rotary Extreme N1 so I would think the Fiberglass would be quality.

From what I heard carbon fiber is one of the strongest material. I have heard of cars getting in accidents and the hood not to be damaged Just so you know.

No question carbon fiber is a whole hell of a lot stronger. They make race car chassis out of it for a reason ;). It's also a lot more expensive, so take your pic.

One thing to consider is that, I have heard lately people saying that some carbon fiber hoods are so light that they give a little under the strength of the wind, causing stress lines in the clearcoat on the hood. Makes me wonder what it would do to paint.

yea but most CF hoods selling today are not full carbonfiber. so they are not that strong.

Yes, everbody knows carbon fiber is stronger. But when is that strength not needed? In my opinion, it's the hood. Does your FD double as a indy car? Do you have girls sitting on your hood?? Do you travel at speeds over 200mph??? A fiberlglass hood is fine for 99% of the people on this forum.


Don't spend the extra cash if you don't care about the bling factor.

carbon is for the look unless you get it made out of 100% dry carbon (and then you save a few lbs hehe).


do not paint a carbon hood, your must as well wear an asshat and flush your money down the drain if you do so!

also, carbon is not the strongest material, it is one of the more ridged though hence you can use less and have it keep the same shape. Kevlar will provide good abraision resistance and will can take impact pretty good. to tell you the truth, the resin/epoxy you use is probally much more important to how it will come out, if you layer anything enuf times, it will get stiff hehe.


P.S. most hoods are just gelcoat and then chop fiberglass on top/under that. cf hoods will ususally just have a layer of cf laied over the gelcoat

I have yet to see a carbon fider hood that is actually all carbon fiber AND built worth a damn. Just because you use carbon fiber doesn't mean it's strong. The far majority of them are just fiberglass hoods with a layer of cf on top like skunks said.

People are too caught up in materials. Selection of materials is only a small part of any problem, implementing them correctly is the key. The far majority of cf stuff you see (unless it's strictly cosmetic, like dash overlays) is complete shit.

<-- This had Chucks's (Rotary Extreme) Fiberglass Hood, and with the impact, and roll, all that happened, is some of the areas around the hood locks cracked, and I have 2 (2mm) deep 3 " Scratches from when they tried to roll the car back on it's wheels... so Fiberglass is plenty strong, unless I was just incredibly lucky....

And when I say crack, I mean a couple of stress fractures, noting Fiberglass bondo, and some sanding won't take out, but I have yet to take it back to the body shop to get it fitted on my new FD....

carbon hoods are made with one and in rae cases maximum 2 layers of CF material (being 204gr/m² if you're lucky)
Then manufacturers put 1 to 2 layers of regular glassmat on it en if they really do good job they finish it with a fiber tissue to give it a nice look from the inside.

The onderhood structure is always in gallsfiber, seldom in CF.

Talking about CF hoods. I would really be curious how many of the hoods really use CF as there is an alternative,being Texalium. It's coloured Glassmat, providing thesame looks but is nothing more than a Fiberglass hood.

If you could get a hood made 100% out of carbon fiber, the structural difference would be noticeable in any spirited driving if your suspension is mostly stock. The stiffer hood will provide suspension benifits similar to that of a front strut tower brace.

And when carbon fiber hoods breaks it doesn't just crack, I heard it shatters.

i highly doubt it would shatter. if your worried about this, just go with a carbon/kevlar mixture, the kevlar will hold it together nicely

Like I said in another threat, the woven kevlar/carbon tissues are worth nothing. True, they SEEM to give the benefits of both materials but they don't. When you have one line of kevlar woven through a carbon tissue, that line wil cut all carbonfibers when bent too much.

The only way to combine Kevlar and carbon is to have them as two separate layers laminated TO eachother and NOT through eachother.

Carbon WILL shater and not break.Carbon has a high bending rate but once you pass it, it will shater away like you have never seen before. On top, the microscopic fibers getting in the air following that shattering are not healthy.

The only 100%CF hood you will find is the one built by yourself or custom made.
The ones for sale on those websites are not meant for any addition of strenght or chassis stiffness. Only for looks (and that's what they do best)
I will build my own 100% carbon hood, as well the hood as the underhood structure. Not for any purpose, I just love to work with the material.

I would presume Chuck's hoods (Rotary Extreme) are all Carbon Fiber, unless he states otherwise.

Skunks is right, it does "shatter". I don't imagine that the hood would fully shatter, but it would splinter very badly across the entire hood. This is one of the advantages of a carbonfiber driveshaft over a steel or aluminum. If it breaks loose, it will "brush" it's self away against the bottom of the car instead of breaking through the floorboard and then through your nuts.

Im getting a carbon fiber hood but I too am going to paint it. There really is no use for one painted except for the fact that you can say you have a carbon fiber hood.

whoa whoa whoa, have you ever worked with kevlar/carbon woven parts??? if so, you would know that it does hold up very nicely. if you bend a peice of kevlar/carbon in 1/2 (like all the way and stomp on it), the carbon will break but the kevlar will not! I'll take some pics of it later if you want but trust me, it wont shatter.

also, dont be afriad of the microscopic fibers getting in the air following that shattering, your gonna get more crap in your lungs in a room with unfiltered air compared to that breif period where your thinking to yourself, holy shit i just killed my car when you crash :) be much more afraid of flipping your car or another car hitting you while your spinning around.

nope, they are carbon with chop mat and gelcoat underneath except for his 100% ones

From everything I've read, carbon fiber pieces are just as strong after being painted as before... if it's done right. I don't know much about forming carbon fiber, but it appears that as long as you do not sand the fiber, it will retain full strength after painting. You could do this by either a) Spraying primer right onto the last layer of carbon, then painting on top of that. or b) Putting a thick layer of resin then sanding, priming, painting that.

Boat builders do this all the time on high-stress parts of boats, and all-over on high-priced kayaks and the like.

There you have it...you are saying it yourself.. the carbon breaks. Wann know why? because you are bending the piece and therefore stretching the tissue structure. You will not be able to beak the kevlar line as it is so strong in the pulling direction, but it hasn't got the ability to stretch as carbon can (carbon is used for impact/bending applications, kevlar for high wear parts)

Again , because you bend the part you will stretch the carbon fibers, but not the kevlar ones. On top the kevlar is so sharp, it will cut the carbon lines, causing it to break.

I admit, for hood applications this is not SO imprtant, but from a manufacturers point of view the carbon/kevlar woven tissue is nothing but a marketing product.

You go ask anybody who is in the business long enough (+20 years) and they will tell you thesame thing