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We've got another awesome project in the works for the 8th-generation Honda Civic Si! Our recently released performance intake system received great feedback from customers, but it also identified an additional need for intake system components. We decided to develop a Civic Si induction hose made from silicone to replace the stock rubber unit.

Stock Civic Si Induction Hose

Before jumping into the design of our prototype hose, check out a few shots of the stock unit.

Stock Honda Civic parts

Stock Honda Civic parts

The stock hose directs airflow coming through the airbox/mass air flow (MAF) housing to the throttle body. This hose has quite a unique route around engine bay components. Two separate flex joints on this piece allow for the engine movement. These areas of the hose are typically prone to cracking and splitting from oil saturation and extended exposure to heat. This hose features two crankcase ventilation (CCV) connection points that will need to be replicated on our design to

If you follow our engineering blog you may have noticed some recent attention on the 8th-generation Civic Si. Well, we aren't making a push for just this generation. We also want to dive into the 9th-generation and develop some unique new parts to improve this awesome car.

Our first project will be quite simple: to produce a Civic Si induction hose that replaces the stock rubber unit. This upgrade provides improved durability as well as pleasing aesthetics for those seeking some engine bay style. We have seen slight power increases with intake hoses developed in the past, so we will be dyno testing our component to bust any myths around power gains.

Stock Civic Si Induction Hose

Stock Honda Civic parts

The stock intake hose is somewhat similar to the 8th-generation piece, but the shape differs slightly and there is one less CCV port on the 9th-generation hose.

As with our 8th-generation unit, we will be creating a smoother silicone piece to provide unrestricted airflow in this portion of

Interested in purchasing our new Civic Si intake system? Check out more details on our product page linked below!

Mishimoto Honda Civic Si Performance Air Intake

Our last write-up for this Civic Si intake included our dyno testing results as well as some insight into our use of 3D printing for rapid prototyping. Since then, we've tweaked our design to provide flawless fitment and we've constructed a final prototype. The last box to check on our list is a final fitment verification and road testing. Our test vehicle owner will be putting some additional road miles on the car and will offer his opinion of the improved intake sound. Soon we will have a new addition to our line of Honda Civic Si parts!

Final Prototype

Mishimoto Honda Civic Si final prototype parts

As we've mentioned previously, this kit is a drop-in replacement for the stock setup. We will include all components needed for installation.

One of the key pieces to this kit is the aluminum intake pipe. Check out a closer look at

Interested in purchasing our new Civic Si intake system? Check out more details on our product page linked below!

Mishimoto Honda Civic Si Performance Air Intake

Now that we had a functional prototype, it was time to perform some dyno testing to ensure that we were on target for producing a power-adding intake system. The dyno results would provide some base-line data so we could move forward with refining our intake design.

Dyno Runs

We quickly strapped the Si onto our Dynojet in preparation for our day of testing.

Honda Civic strapped to Dynojet for intake testing

Honda Civic Si strapped to Dynojet for intake testing

Of course we did some filming during our dyno runs to capture differences in intake sound from the stock Civic Si intake to our prototype. Check out the video below!

Testing Results

Our initial test simply captured power output while monitoring AFRs to ensure that they remained within a safe margin of the stock intake.

Check out the dyno plot from this test!

Dyno plot for

Interested in purchasing our new Civic Si intake system? Check out more details on our product page linked below!

Mishimoto Honda Civic Si Performance Air Intake

Stock Si engine bay

With a K-series power plant, 6-speed manual transmission, and a limited slip differential, the Si is a great choice as a fun commuter that can double as an autocross machine on the weekends. As with any performance vehicle, more power is always on the minds of enthusiasts. Mishimoto has been working to develop brand-new intake systems for a variety of vehicles, and the 8th generation was next on our list for some R&D.

Getting Started

We started with a blank slate on this project. We researched the type of intake we wanted to design as well as where we would place the filter. A true cold-air system would have the filter in the driver-side fender well. Our team investigated the details of installing a true cold-air setup (filter within the fender well) and found the process to be quite extensive. While some DIY