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Carbon Fiber vs. Fiberglass: Texture, Strength, and Cost

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Posted August 14, 2019 in Carbon Fiber, Fiberglass

After waiting years for the right time to take on a Porsche® restoration or upgrade project, you finally decided to buy that new 1974 911 or a 1984 Carrera. The car is in pretty good shape for the most part; it was well maintained, and you purchased it from the original owner, but there are a few pieces here and there that are missing or damaged. You also wouldn’t mind swapping out some of the metal for a lighter material to trim some excess weight.golden porsche 911 exclusive series. limited edition-img-blog

As you research your options, you will find that there are two popular materials that are used for car part replacement: carbon fiber and fiberglass. While most of the sources online will tell you that both can be stronger and lighter than steel, there isn’t much information beyond that.

So, to help you make the most informed decision possible, we have compared three categories that are relevant to car part replacement and restoration to put into perspective which option will best fit your needs. (We will give you a hint, you probably want to go with carbon fiber.)

Texture

It is pretty simple to get your head around exactly what each material is made of. As the names imply, fiberglass is made of small strands of glass that have been melted down, while carbon fiber is made of small strands of carbon atoms. Both materials can then be combined with an epoxy resin to create a stiff product that can fit any shape or mold.

The final products are smooth and resilient compounds that are, as we previously mentioned, lighter and pound for pound stronger than steel. Either choice will make an aesthetically pleasing addition to your project.

Strength

This is what separates the two materials, but it can be the downfall as well. Both types can be made several ways. You can add polyurethane resin to both. The problem with polyurethane is that it does not make a very strong part. Most places do not offer the option to have a fiberglass part made with epoxy resin. We would only recommend a carbon part made with epoxy resin. You can also have carbon parts made with pre-impregnated (pre-preg) carbon. This is a much more expensive option, but this is how true race car and aerospace parts are made. If all three types are painted, they look the same. This is ultimately where the similarities end. When set, fiberglass is a much less rigid material than carbon fiber. This flexibility may have its uses in other areas of manufacturing, but in the auto industry, you typically want your parts to remain as rigid as possible. For this reason, carbon fiber is the go-to option for heavy components like hoods, spoilers, doors, and sometimes even entire body kits.

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When it comes to sheer tensile strength (the amount of tension a material can take before it breaks), carbon fiber once again pulls ahead. Carbon fiber can reach a tensile strength of up to 500 ksi (kilopound per square inch), whereas the most common types of fiberglass generally get up to roughly 300 ksi.

Cost

In addition to being higher in tensile strength, carbon fiber is also higher in price. Pre-preg parts are even more expensive. The process of producing carbon fiber is much more intensive than fiberglass, and the market reflects that cost. Since many manufacturers are often looking for a durable material with some flexibility, there are more producers of fiberglass than carbon fiber, which is also a factor in the current market.

While the price of carbon fiber might be higher (you could be paying upwards of $3,000 for side skirts on a 997 Carrera), it is the stronger and more resilient option.

If you are looking to take on a new Porsche rebuild or restoration project and have questions about whether you should order carbon fiber or fiberglass parts, give our office a call today at (909) 982-9111 to get more information.