2014+ Ford Fiesta ST

We are back with more on our Fiesta ST downpipe project. We know you are long overdue for an update, so we'll dive right in. After fabrication, we read that some other aftermarket downpipes for the Fiesta ST weren't as successful at making power as downpipes typically are on other applications. We still wanted to test our downpipe designs to see the data for ourselves, and decide if the downpipe was worth manufacturing for the Fiesta ST.

After testing was completed, the data confirmed our suspicions that the Fiesta ST is pretty darn efficient on its own, and the addition of a downpipe did not show any gains in power. Even still, we have decided to kick this into production for those who want the sound benefit, and for those who have more modified Fiesta STs.

A tune will be required to run this downpipe, and of course actual power gains will depend the tune itself and the supporting modifications to your ST.

Fiesta ST parts

Final Prototype

Our final prototype arrived today and we wasted

We are nearing the completion of this project. Our engineering team is ready for dyno testing that will verify any power gains made with our larger-diameter intercooler piping. Exactly how much larger is the piping we designed?

The Mishimoto hot-side design provided the greater increase in volume between the two, coming in at a 51% increase over the stock pipe.

Fiesta ST charge pipe volume comparison, cold side

We did not have quite as much room to grow on the cold-side, but we still managed an increase of 22% in internal volume over the stock pipe.

Along with the volume increase, our piping features smooth mandrel bends with minimal interruptions caused by additional connection points or changes in inner pipe diameter.

Testing

Power output data is frequently used for evaluation of a piping upgrade. We will be running tests with each pipe individually and then a final set of runs with both the cold-side and hot-side pipes installed.

To provide

A few weeks ago we completed our first set of prototype pipes. After a quick evaluation by our team, it was time for a vehicle test fit. Last week we set our Fiesta ST (FIST) up on a lift and began swapping the stock piping for our components.

First, the hot-side pipe was bolted into place.

Mishimoto Fiesta ST performance parts installed

The hot-side pipe slid into place perfectly. Our mounting bracket lined up, and the hardware properly secured the pipe into place.

The cold-side pipe was a bit more challenging to install, but soon we had it in place as well.

Mishimoto Fiesta ST performance parts installed

Mishimoto Fiesta ST charge pipe installed

As with the hot side, all components lined up and connected properly. Both our quick-connect vacuum line and the symposer port were properly situated for an easy install. We will need to make one adjustment to this pipe, however; the mounting bracket you see in the images above will be eliminated. We found that the connection points provided ample

It has been a while since we took a look at what is going on in the world of the Fiesta expansion tank. In our last post we test fitted our 3D-printed prototype on the Fiesta ST. After fitment was confirmed, we played the waiting game for our final prototype's arrival at our development facility. Our best efforts at being patient paid off when we had two packages arrive this morning!

Fiesta ST expansion tank

Fiesta ST expansion tank

Each expansion tank comes with an overflow hose and two rubber sleeves. The stock expansion tank is plastic, so rattling on the mounting points is not an issue. However, after upgrading the expansion tank to our all-aluminum version, we needed to prevent any rattling that may occur. The addition of these two rubber sleeves should do the trick! They slide over the stock mounting pegs to ensure that there will be no unnecessary rattling under the hood. After just a few minutes the expansion tank was installed and is looking great alongside Mishimoto's other Fiesta

Good news! Our first prototype intercooler pipe kit is complete. We can now evaluate both fitment and functionality on our Fiesta. Let's take a look at each pipe we created.

Prototype Cold-Side

First we have the more complex pipe of the pair, the cold-side.

Fiesta ST charge pipe prototype

Complexity comes in the way of multiple bends combined with numerous pipe-mounted features. To the right side of the pipe, you can see the flat flange that serves as a mounting point for the factory pressure sensor. This flange is CNC-machined to provide a proper seal.

Fiesta ST charge pipe prototype

Just down the pipe from this flange you can see a mounting bracket and a nipple. The bracket is a component that may be eliminated from our design. We are evaluating the rigidity of the design with and without the additional bracket to determine if it is needed. The nipple attaches to a quick disconnect vacuum line running throughout the engine bay. Here is another look at the pipe.

Fiesta ST charge pipe prototype

It's been a while since our last update on the Fiesta ST cat-back exhaust and we are excited to let you in on the details of the final prototype! The last detail to square away was the exhaust tips. While the tips we had were decent, we found them a little on the plain side so we switched it up. Rather than the single-wall tips, we went with a dual-walled setup that we think look much better on the ST and will hold up better over time. Check out some photos below!

Fiesta ST exhaust tips

Welding some Fiesta ST parts

Fiesta ST exhaust tips

For comparison, here is a shot of all three tips that we have worked with on Fiesta ST exhaust. On the far right you'll see our good buddy, the stock exhaust, with its awkwardly large muffler. You had a good run, old friend. The center is our first prototype, a bit more on target but we saw room for improvement. Finally, the star of our post, our double-walled tips looking mighty fine closest to us on the left.

Fiesta ST exhaust tips

Fiesta ST exhaust tips

Stock Cold-Side Features

We had it pretty easy during the design phase of our hot-side intercooler pipe. A simple design with relatively common features, not overly complicated. The cold-side is a different story.

Stock Fiesta ST charge pipe

As you can see, this pipe features a few complex pieces and also follows an unusual path. On the right side at the top of this image, you can see the end of the pipe that mates to the intercooler coupler and hose. This portion of the pipe also houses a pressure sensor, a mounting bracket, and a vacuum-line port.

Stock Fiesta ST charge pipe

Each of these features will be replicated in our design, and in addition we will be increasing the piping size to 2.5" throughout. The stock piping features ends with 2.5" diameters; however, most of the inner portion of the pipe measures around 2" in diameter. The stock throttle-body diameter measures in at 2.25", so we will be using a reducing coupler at this connection point.

The other end of the pipe features

In our last post we took a look at the stock Fiesta ST downpipe as well as our slotted flange design based on the stock flange. We are still planning to create both a catted downpipe and a non-catted downpipe for race applications, so let's take a look at the progress!

Downpipe Design

After fitting the flange to the turbo, we began to piece together the rest of the downpipe coming off the flange and meeting with the exhaust. Both our designs feature a slotted flange that bolts to the turbo, in addition to a flex pipe near where they meet with the exhaust. This is important because the entire exhaust system will move a bit, and we need a flex point to allow for this. Not allowing room for flex in the downpipe would most certainly harm your exhaust system and possibly the turbo itself.
We began by laying out the components of our prototype next to the stock Fiesta ST downpipe for comparison. Check out some shots below!

Layout of piping to create the catted Fiesta ST downpipe

Fabrication

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