HOW TO MAKE A CARBON FIBER MUSTANG GT AIR INTAKE

August 06, 2017 4 min read

HOW TO MAKE A CARBON FIBER MUSTANG GT AIR INTAKE

Platform: 2010 Mustang GT

Design: Individual

Idea Creation

A typical carbon fiber cold air intake requires expensive tooling to make, including machined matched aluminum tools and a custom bladder. An individual requested we make a beautiful intake for a 2010 Mustang GT as quickly and inexpensively as possible.

Plug Creation

Using just some cardboard and MDF board, we mocked up the general shape we were looking to create and made sure it would fit inside the car.  Our friends at Ozzy Motors lent us the car for one day, so it was important to make sure we got these all right before we had to say goodbye to her.

DIY Custom Carbon Fiber Mustang GT Air Intake Original

We transferred the dimension of the filter outlet and the throttle body inlet onto the two pieces of ¼” MDF and then sanded them to the correct size.  We did this so that we could ensure that the final carbon part would fit exactly onto the necessary components. 

DIY Custom Carbon Fiber Mustang GT Air Intake Plug

Starting with a large block of high density foam, we drew out the general shape of the intake, including both end dimensions, and began trimming down the edges.  It is important to go slow here so that you don’t cut out too much material off.  It is a whole lot harder to fill holes than sand high spots. 

DIY Custom Carbon Fiber Mustang GT Air Intake Plug

DIY Custom Carbon Fiber Mustang GT Air Intake Plug

DIY Custom Carbon Fiber Mustang GT Air Intake Plug

After a bit more work with the hand saw and surform blades, the part began to take shape.  Once the dimensions were close, it was test fit in the car to see where it interfered with other components and where it needed to be trimmed down.

DIY Custom Carbon Fiber Mustang GT Air Intake Plug

A few iterations of this and the part was ready to go! All dimensions lined up and a quick final sanding left the foam plug looking just how we wanted it.

DIY Custom Carbon Fiber Mustang GT Air Intake Plug

A plug is typically sprayed in a sanding primer and then sanded to final perfection.  One gallon of this primer typically costs $130.  A tricky way to save some money and still get a nice surface finish is to use electrical tape.  Electrical tape acts as a release film and no epoxy will stick to it so it is great for many composite applications.  In this instance, we wrapped the entire plug in it, making sure each layer overlapped so that no foam showed through (of course we somehow missed a small spot...). 

DIY Custom Carbon Fiber Mustang GT Air Intake Plug

Missed a picture here, but if you look closely at this picture you will see that the end of the plug is now bulked up and changes contours.  These were two additional pieces of foam sanded to the shape of the MDF boards so that the end of the part would be flat.  This allowed the hose clamp around the rubber seals to sit properly on the final part.

DIY Custom Carbon Fiber Mustang GT Air Intake Plug

For more information on building a plug, check out our process blogs on splash plug fabricationmachining a foam plug, and plug finishing.

Layup Process

With the plug ready to go, it was layup time! Before getting the carbon wet, we cut the carbon to the perfect shape so that it would wrap around without too much overlap.  On this particular intake we used three layers of 6K twill carbon fiber. We did the first two layers on this first layup, and then followed with a third layer to cosmetically skin it.  All excess carbon was trimmed so that limited wrinkles would be introduced to the part. 

DIY Custom Carbon Fiber Mustang GT Air Intake Lay-Up

The part was then placed in an envelope vacuum bag and sealed.  We used a 4:1 epoxy resin system with a medium length cure time so we left the part under vacuum for approximately 4 hours and then let it sit for an additional 10 before opening. 

DIY Custom Carbon Fiber Mustang GT Air Intake Lay-Up

DIY Custom Carbon Fiber Mustang GT Air Intake Lay-Up

As mentioned above, we planned to do one final skin layer after the first two had cured.  This gave us the opportunity to sand any wrinkles out of the first two layers so that the final layer would be perfect.  The image below is of the part after one round of sanding.

DIY Custom Carbon Fiber Mustang GT Air Intake Lay-Up

The final layer was then applied in a single vacuum bag with no additional release or breather bleeder.  This method allows for the vacuum bag to be spread tight across the part and wrinkles eliminated.  We also made sure that the seam of the carbon and the vacuum bag were on the bottom of the part with the vacuum port on the open end. 

DIY Custom Carbon Fiber Mustang GT Air Intake Lay-Up

The result directly out of the bag follows.  As can be seen, the surface finish is decent, but one last sanding and a clear coat will make it truly shine. 

DIY Custom Carbon Fiber Mustang GT Air Intake Lay-Up

Part Finishing

Of course, it’s hard to use an air intake if it is full of foam.  The next step required removing all the foam from the inside with drills and hand tools.  Once started, the electrical tape could be used to help peel the remaining material out. 

DIY Custom Carbon Fiber Mustang GT Air Intake Finishing

 

The interior can be seen in the following picture just after the electrical tape was removed.  It creates a slightly ribbed surface finish, but that can be quickly sanded smooth with some light sand paper.

DIY Custom Carbon Fiber Mustang GT Air Intake Finishing

With the foam removed and the interior walls cleaned up the part was ready for a final trim, fitting, and some clear coat.

DIY Custom Carbon Fiber Mustang GT Air Intake Part Finishing

You can learn more about the intricacies of the finishing process in our posts on trimming carbon fiber, how to spray clear coat and buffing and polishing best practices.  

Final Build

As the part is used within the engine bay of this Mustang alongside a 4.6L V8 engine we knew it would get a little warm.  For this reason we decided to do the final clear coat in 500o F rated Engine Enamel.  This would provide an extra layer of protection for the carbon as well as a nice sheen!

DIY Custom Carbon Fiber Mustang GT Air Intake Final

 


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