Oct 282015

Upon the release of our PERRIN Electronic Servo Driven Gauges, we stumbled onto a perfect part to make, that would compliment them being installed on a 2015 WRX or STI. Something everyone would need and could afford!

In the past, we would have to slit a large rubber boot behind the turbo to fish wires and things through to get from the inside of the car to the engine bay. This was a simple location, but the issue is water and noise. Doing this opened up the door for water getting into the passenger foot well as well as you would hear engine noise a bit more. We just dealt with this on the 2002-20014 cars(as I am sure everyone has), but now on the 2015’s we stumbled across a pretty cool solution.


Subaru was nice enough to install a hole in the firewall just for us to use for passing wires and other things from the interior of the car to the engine bay. I know, they didn’t do this just for us, but we saw a perfect opportunity to make a part that any customer buying gauges, or installing things like water methanol injection or NOS systems would use. You can see the location of the hole in the above picture, which is in the same place on the STI and WRX. There difference is on the WRX, there is a simple plug where the STI has the sound generator tube installed. This is that weird tube that connects to the intake system and pipes sound to the inside of the car.



This hole opens up to the cavity where the windshield wiper motor/hardware resides as well as where the HVAC system sucks in fresh air. Within this cavity is another hole that is perfectly located to run wires and/or hoses completly out of the way of a passenger (or driver if in another country) and down to the frame rail. Just like the engine bay hole, it is covered by a plug on the WRX and on the STI the remaining section of the sound generator passes through it. In both situations, running regular wires through them will leave open holes, let in sound, water, air and look terrible, so we designed the PERRIN Firewall Grommet!

asm-gau-120_01 asm-gau-120_04

The PERRIN Grommet was the first rubber OEM type part we ever made. We have made many previous parts in urethane, but in testing, we just weren’t happy with the way it looked or functioned.  Using OEM type molding methods, we were able to create a part that will perfectly compliment any engine bay. You can see in the pictures below an example of  our plug being used during an installation of PERRIN oil pressure, fuel pressure gauges, and an Aquamist HFS-4 system. There is plenty enough room for 8 separate wires and hoses passing through it. In this example there is enough room to run 4 more sets of wires for gauges and maybe enough a power wire for a stereo system!


You can see in the bigger picture that all that is left to do is snug up the zip-tie and the installation is complete. We felt this was and important feature to ensure the wires were secure as well as relatively sealed from weather and heat from the engine. The


One last thing! If you look at the WRX and STI pictures you will notice that there are two holes! That means there are two places to install a PERRIN Firewall Grommet. While we will be selling them separately, we do expect most customers to buy two at a time. It is such an inexpensive part that there is no reason to not get two :)

We expect this part to do well enough that we will expand this into other sizes and fitments for other popular Subarus. So keep an eye out for more items like this from us!

 Posted by on October 28, 2015 About Your Car, Part Design & Tech

Sorry, the comment form is closed at this time.