Baking tape being applied to Fiesta ST intake hose

Fresh Air for the Fiesta! ST Performance Intake R&D, Part 3: Making a Silicone Inlet Hose

This is a pretty cool post, something a bit out of the ordinary for our projects. We typically utilize our existing silicone boots in our intercooler kits, intake systems, etc. For this project, we decided to manufacture the first portion of our intake system from a wire-reinforced silicone hose. This would facilitate an easier installation, and it would also provide a smooth airflow transition from the small turbocharger compressor inlet to our intake’s large pipe diameter. Since we like to show you what goes into developing our prototypes, check out the process for creating our silicone turbo inlet hose below!

Printing Our Fixture

The hose we have in mind will follow the path of the stock induction hose, which is actually a plastic piece on the stock ST. Before beginning our silicone project, we needed a fixture that would serve as a base for the silicone layers that will be applied. After making a model in Solidworks, we fired up the 3D printer and watched as it churned out our component.

Printing 3D silicone Ford Fiesta ST intake hose fixture
Printing 3D silicone Ford Fiesta ST intake hose fixture
Printing 3D silicone Fiesta ST intake hose fixture
Printing 3D silicone Fiesta ST intake hose fixture

And our end result is below!

3D-printed silicone Fiesta ST intake hose fixture
3D-printed silicone Fiesta ST intake hose fixture

As you can see, the diameter of this pipe gradually increases from small to large. The outer diameter of this fixture will become the inner diameter of our completed silicone inlet hose.

Silicone Inlet Hose Creation

We’ve got some work to do! Our first layer of material is standard silicone, which is wrapped around the fixture until the entire piece is covered in a single, flat layer.

Silicone hose layer 1 for Fiesta ST parts
Silicone hose layer 1 for Fiesta ST parts
Silicone hose layer 1 for Ford Fiesta ST intake hose
Silicone hose layer 1 for Ford Fiesta ST intake hose

After some careful work, our first layer was complete.

Silicone hose layer 1 for Ford Fiesta ST intake hose
Silicone hose layer 1 for Ford Fiesta ST intake hose

Our second layer would be a slightly different material. Check it out below.

Fiber-embedded silicone layer for Fiesta ST parts
Fiber-embedded silicone layer for Fiesta ST parts

This layer is composed of fiber-embedded silicone, and it is the key component for the rigidity and strength needed in our end product. The fibers provide greater pressure tolerance, making it ideal for any pressurized system (e.g., cooling, CAC).

Like the standard silicone, this layer is wrapped around the fixture in a similar fashion.

Fiber-reinforced silicone layer for Fiesta ST parts
Fiber-reinforced silicone layer for Fiesta ST parts

The next portion of this build is a bit out of the ordinary for your typical silicone hose. Normal hoses and boots encompass the silicone and fiber layers, but for this inlet hose, we will be using metal wire to further reinforce the integrity of the hose. Why? Well, standard silicone hoses tend to collapse under extreme vacuum or suction, which is exactly what this hose will see. All our hoses that attach directly to a turbocharger compressor inlet are wire-reinforced for additional strength.

The wire is wound around the hose throughout its entire length.

Wire-reinforced layer for Fiesta ST parts
Wire-reinforced layer for Fiesta ST parts

The image below shows our Fiesta prototype next to a cutaway of our Subaru WRX turbo inlet hose, which also features wire reinforcement. Our final rendition of the Fiesta induction hose will likely feature thicker wire with less winds, similar to the WRX piece.

Wire-reinforced layer (top) and Subaru WRX inlet hose (bottom)
Wire-reinforced layer (top) and Subaru WRX inlet hose (bottom)

Our next layer is yet another slice of silicone on the sandwich that is our Fiesta inlet hose. Or perhaps it’s more like a wrap? Anyway, another layer of silicone is applied over the wire.

Third layer of silicone material for Ford Fiesta ST intake
Third layer of silicone material for Ford Fiesta ST intake

Another layer of fiber-reinforced material is added, followed by a final layer of plain silicone, resulting in our four-ply induction hose. I won’t bore you with more images of Mike wrapping these last two layers on the fixture, but I assure you he did it!

We’re not finished yet. There are a few more steps as we progress toward a completed silicone hose. Our next step is to wrap the hose in a protective tape to keep the silicone in place for baking. This tape is resistant to our baking temperature and will keep the silicone in position during the process.

Baking tape being applied to Fiesta ST intake hose
Baking tape being applied to Fiesta ST intake hose

This “tape” is not sticky and does not adhere to the silicone. It is wound tightly around the pipe to compress the silicone to its final shape.

Silicone Fiesta ST intake hose ready for baking
Silicone Fiesta ST intake hose ready for baking

The tedious portion of the process is now complete. From here out, it is as simple as baking a batch of brownies. We fired up the oven, popped in our hose, and waited while the silicone cured.

Note: Don’t do this at home. Baking silicone in the oven releases a pungent odor that will fill your house and ruin any meals cooked in that oven for the next few days.

Silicone hose baking for Fiesta ST parts
Silicone hose baking for Fiesta ST parts

Once we completed the numerous baking sessions and the hose had cooled, we trimmed the edges to our desired length. This revealed the numerous layers of material, similar to what you would see with any of our silicone products.

Ford Fiesta ST intake silicone hose
Ford Fiesta ST intake silicone hose

The baking tape was then removed, revealing our final product!

Mishimoto silicone turbo intake hose, final product
Mishimoto silicone turbo intake hose, final product

We even test fit this piece on the car with our intake piping!

Silicone Ford Fiesta ST intake hose installed
Silicone Ford Fiesta ST intake hose installed

Coming Up!

Before dyno testing we still have one important portion of our intake to tackle: the airbox. We have some pretty interesting plans for the design, so expect a post crammed with cutting, bending, welding, and plenty of flying sparks.

Thanks for reading!

-John

4 thoughts on “Fresh Air for the Fiesta! ST Performance Intake R&D, Part 3: Making a Silicone Inlet Hose”

    1. Good question, I left that part out. After baking, the plastic component is still in place. Once the item cools, we hit the outer portion with a rubber hammer to fracture the plastic piece and remove it from the silicone hose. When wrapped, the silicone does not adhere to the surface so removal is quite simple.

      Thanks for checking out our post!
      -John

    1. The clear layer? This is actually more of a wrap than an actual tape, it does not have any adhesive. The point of this layer is to compress the hose and keep it together during the baking process. The material has a specific melting temperature so the silicone will melt together but the tape will be unaffected. Pretty cool!
      -John

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