Mishimoto Honda Civic parts testing

Smooth Airflow For The 8th-Gen. Mishimoto Civic Si Induction Hose R&D

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
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 provide bolt-on fitment.

Mishimoto Prototype

After capturing the dimensions needed from the stock hose, our team went to work designing the silicone counterpart. Check out our first prototype unit!

Mishimoto prototype Honda Civic performance parts
Mishimoto prototype Honda Civic performance parts
Mishimoto prototype Honda Civic performance parts
Mishimoto prototype Honda Civic performance parts

As you can see we’ve matched the contours of the stock hose while providing a smoother component. In addition, we’ve molded both CCV connection points into our design.

Mishimoto prototype Honda Civic performance parts
Mishimoto prototype Honda Civic performance parts

Our prototype hose is a five-ply silicone unit that will provide optimal durability and much greater longevity than the stock rubber piece.

Prototype Installation

Time to install our first prototype to ensure fitment is spot-on.

Mishimoto Civic Si induction hose installed
Mishimoto Civic Si induction hose installed
Mishimoto Civic Si induction hose installed
Mishimoto Civic Si induction hose installed

As we expected, this piece fit just like the stock hose, and both CCV connection points aligned perfectly. A successful installation!

Dyno Testing

Next, we needed to verify our design and see if any power increases occurred. Although we did not see any gains with our 9th-generation induction hose, we decided that it wouldn’t hurt to test the 8th-generation hose as well.

First we set up the vehicle on our Dynapack™.

Mishimoto Civic Si induction hose installed
Mishimoto Civic Si induction hose installed
Honda Civic performance parts testing
Honda Civic performance parts testing

Once the vehicle was situated on the dyno, we began making pulls with the stock hose installed and then with our silicone induction hose installed.

Mishimoto Honda Civic parts testing
Mishimoto Honda Civic parts testing

Check out a couple clips from testing!

Dyno Results

As with the testing of our 9th-generation Civic, we did not see any appreciable gains on our stock test vehicle. Check out the plot below.

Mishimoto Honda Civic parts testing results
Mishimoto Honda Civic parts testing results

Both plots follow a similar path, and you can definitely see the impact of VTEC. At the top end of the plot we do see some gains of 1–2 whp and 1–2 wtq. With additional airflow from a bolt-on and/or tuned vehicle, gains in the upper end of the range could be a bit more significant.

For a stock vehicle, the primary benefits of this hose include improved durability and longevity. In addition, the aesthetic styling is improved over the stock piece.

Product Release

This induction hose is now released and available for purchase. Be sure to check with our vendors for availability.

Thanks for reading!

-John

2 thoughts on “Smooth Airflow For The 8th-Gen. Mishimoto Civic Si Induction Hose R&D”

    1. Hi Aris!

      This induction hose would require trimming to work with a 3/4″ throttle body spacer. We would suggest starting by trimming 1/2″ and test fitting in order to avoid cutting the hose too short.

      To trim the hose, we would recommend marking the cut line all the way around the hose with painters tape, then use a sharp razor blade to cut along that line.

      Feel free to let us know if you have any more questions! Thanks!

      -Steve

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