How To - 3,800cc of injectors for $200. Fuel Rail Modification.
 

The tall style Denso injectors in our system are a pain to find in larger sizes. Meanwhile Subaru uses the same top feed style Denso except with a shorter body. Same wire connectors. With some minor modification to the secondary fuel rail, and none to the primary you can easily and cheaply boost your fuel capacity. Hella Cheap. 4 950cc chinese injectors are like $200CDN on ebay. Used real Denso 565s from peoples subaru upgrades are also easy to find.

The difference in length is 8mm.

You will need a very low capacity mig welder with mild steel wire. The material is only 1/8" (.125"). A grinder, A Drill and a Vise will be useful. This method does not require welding on the body of the rail so you don't have to worry about being a pressure welder.

A number of these pictures are from like 2 years ago but I will try to explain best I can.
https://cimg3.ibsrv.net/gimg/www.rx8...b09f8fd19a.jpg

The mounting surface of the rail is parallel to the injector cups. If you get distortion after welding this is a good thing to keep in mind. This will not change with height of the rail.

https://cimg5.ibsrv.net/gimg/www.rx8...7e88dc82e3.jpg

Next you'll need to make 2 tabs to become your extensions. I seem to remember cutting 1/8" plate to 3/4" wide for these. Bend to 90 degrees in a vice or break press.

https://cimg7.ibsrv.net/gimg/www.rx8...56757fe8e3.jpg

The next part is CRITICAL. The difference in injector length is 8mm but I wanted a little extra push so made my rail 9mm lower. That is NOT 9mm of washesr it is 9mm from mounting face to mounting face.
https://cimg2.ibsrv.net/gimg/www.rx8...6be872114f.jpg


The CRITICAL PART is when you bolt your tabs to the existing mounts you want the gap to be tight but DO NOT BEND THE OE MOUNT AT ALL THIS WILL F UP THE MOUNTING ANGLE.
https://cimg5.ibsrv.net/gimg/www.rx8...f5325da611.jpg

I gently beveled that edge with a hand file until there was no flex.

https://cimg3.ibsrv.net/gimg/www.rx8...c122ea16e5.jpg


Next tack that shit up. Try and get them right on the sides to hold the shape a bit more.

https://cimg9.ibsrv.net/gimg/www.rx8...5be5bdbba0.jpg

Weld the easy side first. Then come in with a zip cut on your grinder and cut the factory tabs free.

https://cimg6.ibsrv.net/gimg/www.rx8...7925388ab1.jpg
https://cimg7.ibsrv.net/gimg/www.rx8...6760a1c480.jpg

It shouldn't noticeably deform. Then weld the inside.
https://cimg1.ibsrv.net/gimg/www.rx8...8f507c7b27.jpg
https://cimg2.ibsrv.net/gimg/www.rx8...a7d87778da.jpg

If it looks square you have had success.


https://cimg8.ibsrv.net/gimg/www.rx8...d58ee18ecb.jpg

Installed looks like this.


https://cimg3.ibsrv.net/gimg/www.rx8...2ffbc57b3e.jpg

Now at this point you could pat yourself on the back and just run these as secondaries and this is probably the smart thing to do. I you are like me and only have 4 injector drivers You can remove that spacer block (OMP Vac Block) and run these shorter injectors as primaries as well. That will look something like this.


https://cimg0.ibsrv.net/gimg/www.rx8...720d55cd51.jpg
https://cimg1.ibsrv.net/gimg/www.rx8...6a08529053.jpg

Always Check for leaks! I have had no issues.

Good Luck

Cheers