Prototype Fabrication

After experimenting with some boxed designs in Part 1 of this write-up, it was time to turn our attention to a shrouded setup, similar to what we offer for the 2008–2014 models. We’re hoping we could utilize the piping from our existing kit, which is well designed and has proven power gains. After placing the shroud into position, we found that it would certainly fit, but would require some modification. The fabrication work began! Check out a few shots taken during the process.

Once all fab work was completed, we had a functional shroud that we could use for testing purposes. We could also use this shroud to develop a 3D model for our production units. Take a look!

We could then combine this shroud with our intake pipe, shown below, to capture some performance data.

This pipe features a stock MAF housing, as well as an air straightener to provide laminar flow across the sensor.

Check back next time for a look at the testing process, and the results from our dyno pulls! Check out the teaser shot of this car getting setup on the dyno!

Time to see what kind of power gains we are able to achieve with our intake design! First, we strapped this Launch Edition to the dynamometer.

Then we began making pulls. On our first day we tested only the stock intake system. Once complete, we installed the Mishimoto intake system and sent the vehicle out for some road testing. We wanted to allow the ECU to adjust to the new intake before making our pulls. After well over 150 miles of road use, we returned the next day to compile dyno data for the Mishimoto intake.

Testing Results

So how did we do? Well, I think the plots below summarize our results quite well.

As you can see, our intake made a great impact on performance, especially at the upper end of the rpm range. The biggest gains occurred from around 5,000 rpm to redline. We saw peak power increases of nearly 20 whp and around 6 wtq. We also saw maximum gains of 22 whp and 17 wtq.

With our past intakes that make power on the stock tune, we have had a few inquiries regarding engine longevity, AFRs, and knock. Our AFR charts for the runs above are shown below.

Although leaner than the stock curve, we are still well within a safe range for engine operation up through redline. Also, we experienced zero counts of knock during our dyno and road testing. These results were expected and are similar to those from our 2008–2014 intake system.

Intake Shroud Design

Now that we had positive testing results, we could move forward with producing our STI-specific shroud to get this product on the market! Check out a rendering of the design in 3D!

As noted earlier in this article series, we would be tackling a race intake system to go along with our bolt-on unit. So what makes the race system different? For this particular system we are using a larger-diameter intake pipe with a larger MAF housing. This means greater intake flow, but it also means it will no longer function with the factory tune. This system is meant specifically for drivers who want aggressive professional tunes so they can take advantage of airflow modifications such as larger turbochargers and high boost pressures.

Because the 15’ model shares the EJ from the previous generation, we would be using the same intake pipe and filter as we did with our 2008–2014 kit. This unit is shown below.

Here is a look at this system fitted to a 2010 STi!

So, all we truly needed was to design an airbox that would accommodate this pipe and function with the body of the new 15’ model.

We hit Solidworks and came up with the design you see below!