FI Air canister mod

Discussion in 'Discussion Forum' started by syata, Oct 23, 2018.

  1. syata

    syata True Classic

    i recall this being discussed years ago in modifying the air canister on the fuel injected X1/9s by drilling holes in it. I can’t find the link to this.
    Can someone post pictures of this modification and detail on how they did this like drill bit size.
  2. Eastep

    Eastep True Classic

    I'm pretty sure that you drill the holes on the side farthest to the left, as to avoid sucking hot air in. As much as possible,anyway. You can drill many, many small holes. Several medium holes, or a couple large holes. In groups such as Volkswagen, Honda and some Porsche, this is referred to as "Swiss cheese"ing your air box.
    Last edited: Oct 24, 2018
  3. ArtBasement

    ArtBasement Erwin Timmers

    I drilled a large hole in mine right next to the side air intake. The snorkel sucks air from the lower center part of the engine bay; adding a hole on the side could only help imho
  4. ecohen2

    ecohen2 True Classic

    Arlington Va
    Does it make a difference?
  5. Eastep

    Eastep True Classic

    didn't do much on my Mk2 GTi, with the same Bosch Jetronic. Can't imagine the X1/9 fairing any better. The sound does increase the sensation of performance gains. I think uprrated injectors, fuel pump and either a chip or other MAF modifications, would net more tangible results. Just my unsolicited $.02
  6. kmead

    kmead Insufferable dum bass

    I doubt there is a measurable difference by drilling the holes.

    A set of tests is worth much more than all of our opinions. Acceleration tests 0-60, 30-60

    Ultimately until you have done some other things to the engine itself not the things bolted to it, the amount of air that can get into the air cleaner is likely not the limiting performance factor.
    lookforjoe likes this.
  7. JimD

    JimD Waiting for Godot... Moderator

    Missouri, USA
    Just remove the stock air cleaner and stick a canister or cone style filter on the AFM. If you don't find a difference with the straight filter, there is no point in drilling holes in your stock air cleaner.

    FI air filter 1.JPG
    Eastep, lookforjoe and kmead like this.
  8. beezee

    beezee True Classic

    Looking at the restriction offered by the stock AFM, it is doubtful there would be much to gain by modifying the air box. Having said that, I would be interested in hearing a response from someone who has made the modification. I am curious if the exhaust side, namely the catalytic converter, is where there is a restriction. Is there any benefit to a higher flow cat?

  9. Eastep

    Eastep True Classic

    I have a dual outlet Euro manifold with dual down pipe from a Yugo, into a catless system. I increased the exhaust diameter to 2.25in. The results were profound! The noise is noticeably improved as well. My X is a de-smogged carb'd car, so I'm not sure how the FI cars will react. Although, again on one of my old Mk2 GTi, I ran a Swiss cheesed Air box w/a free flowing 2.25 in exhaust, and there were definite improvements. The problem is that the Bosch ecu & afm are the limiting factors. Hence why I previously suggested installing a chip and uprrated injectors & pump ;)
    nichol01 likes this.
  10. carl

    carl True Classic

    My 2008 Mazda 3 had a convoluted intake snorkel and it was asked on the forum for them if removing the main part would add power. This was apparently a big topic and it was determined that it added no power but the intake noise was amazing and worth it for that alone. I did the mod and was totally happy and it really roared at full throttle. It's not only about actual power increase but how it sounds or feels to the driving experience.
    Eastep and lookforjoe like this.
  11. MikeHynes

    MikeHynes True Classic

    Goodfield, IL.
    I cut one big hole in mine.
    The reason I did that is two-fold. One, I wanted to increase the size of the air intake on the stock filter canister. I thought the stock one looked pretty small, maybe made small enough to mitigate the intake noise???
    And most importantly I wanted to get cooler air from the side scoop (I removed the inner plastic scoop).
    I used a cut up HVAC duct, it fit pretty well.
    I can't say that it increased performance at all, I never did dyno it. And it certainly didn't impress anyone. The car ran well enough to win a few races though, so I don't think it hurt the performance at all and the cost was pretty low. At least I tried.

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