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Decapping top feed injectors - how to


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This is easy to do and turns your pink 565cc STi injectors into 800-900cc in 15 minutes. Ive done a few sets now with no issues and also run them for over a year now. The standard top feeds whatever colour they are can be decapped also but unsure what cc they come out to. This is not a bolt on mod you need to tune/tweak fuel map to suit or it will borewash like crazy I wouldnt recommend driving it anywhere it will likely foul your plugs on the rich cold start.

The V5/6 yellows are decappable but are welded on the end so you need to hold them adjacent to the paper so its a hell of a lot more delicate I recommend you send them to someone else to decap.

What you need:

1x 200*300mm Sheet of 80G sandpaper any quality will work.

4x Top feed injectors

The caps are welded on the side you can see the weld in the below pic:



Note - The first one will probably take you as long as it takes to do the last 3 as you will be freaking out about going too far. Keep checking it and you will be fine.

I held the injector so i could roll it as I scratched it across the paper so it grinds it evenly. I found holding it on a 45deg angle worksd best. You can see when the cap has seperated from the side so check it as you go. The cap will just fall off when its ground right off around the edge DO NOT get impatient and lever it off with a screwdriver I imagine you will either hurt yourself or damage it.


I used this much sandpaper on one injector:


Finished result. Just clean up any sharp edges with the sandpaper.




The set Im running came out as follows:

Injectors are pretty much 840cc @ 3 bar.

Inj #1 838cc

Inj #2 842cc

Inj #3 836cc

Inj #4 844cc

The sets Ive done Ive sent to D-Tech in Tauraunga who ultrasonic cleaned and flowtested them. Overnight service would definitely recommend. I wont names prices but Tonys welcome to add if he wishes.

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