Upgrading stock FJ20 370cc injectors with Mazda 550cc - Article done by BoostedFrog from FJ20.com
Model of Car to Source Parts;
Mazda rx7 series 4-5
Parts Required
1. Mazda Rx7 550cc Injectors (make sure you get the turbo injectors) - Prices of around $100 - 250 for a set of 4 is the going rate. Simply put a wanted ad up on ausrotary.com.
2. Clips from Old fj20 injectors
How to do it
The pictures attached to this post do the explaining, but for those that prefer reading I'll try and explain it here. The main thing to remember is that you can only use top feed injectors for this modification.
Remove your standard FJ20 injectors from your inlet manifold by removing the fuel line and the screws.
Remove the parts shown from your stock fj20 injectors (both rubber collars & insulating block).
Get your Mazda Injectors and reverse the process by fitting the parts you removed from the stock fj20 injectors.
Once completed, its worthwhile getting replacement rubber O-rings for the ends, as in my cases they are over 20 years old.
Install the new 550's into the inlet manifold, refit the fuel rail and go racing.
Note - It's recommended to get a set of injectors cleaned before installation if they are coming out of a car with no history, this service costs around $25 per injector.
Skyline GTR Top feed injectors (444cc) can also be used.