Port Injection Explained and Guide

The OEM fuel system with e30 is good to about 370whp or so before you start to see some wild IDC "injector duty cycle" To fix this people will run port injection on top of the direct injection system. This provides fuel when you need it the most "higher boost" and supplements the OEM system.

This thread is to clear up some confusion on port injection and the multiple ways to do it. There are already some threads on it which I will be referencing. This will not cover the split second controller which is needed to control the PI "port injection" injectors. All of these are e85 safe "most people do e30 - e50 blends" I recommend checking out these threads as well for some more info.

***Added some good info form PurpleDrank "Will" and Freektune "Justin" to the bottom.

https://mazdaspeeds.org/index.php?threads/how-to-returnless-port-injection-setup.9707/
https://www.mazdaspeeds.org/index.php?threads/diy-port-injection-set-up.2579/


I will be going through Return-less PI, Return PI, Surge Tank PI, Fuel Cell PI

Return-less Port Injection:
Goal < 500whp

Returnless works well if you want to stay around 500whp, it is pretty simple. After 500whp you will need more fuel flow and the stock regulator will get wonky. This is when you would move to a Return style. This is how I would do it, it is not super fancy but it is cost effective and will work just as well as the PTFE or other ways. This uses the factor in basket fuel pressure regulator. This is the same for 6th port as it would be for doing a PI rail.

Items Needed:

1. In Tank: Upgraded Drop in Pump
   1. AEM E85 High Flow In-Tank Fuel Pump - 340LPH
      PART# AEM 50-1220
2. Fittings
   1. Firewall - OEM Feed - 6AN Male Flare to 5/16
   2. Firewall - 6an to 6an 90 - Female 6AN To 3/8
   3. Hose - Gates 27349 Barricade Fuel Injection Hose-15' Length, Inner Diameter 3/8"
   4. HPFP - Female 6AN AN6 To 3/8 Barb
   5. HPFP - Black Aluminum -6 AN Male Thread Flare Tee Union T
   6. HPFP - Hard Fuel Tubing Fitting for hardline tube 5/16" to AN6 female thread
   7. HPFP - to PI rail - Female 6AN AN6 To 3/8 Barb
   8. Hose - Gates
   9. PI Rail End 1 - 6AN 45 Degree Push Lock Hose Fitting End Black
   10. PI Rail End 1- ICT Billet -6AN Flare to 6 Oring ORB Male
       
   11. PI Rail End 2 - Aluminum -6 AN Male Hex Head Socket ORB
   12. #16 Stainless Steel 3/8" Fuel Injection Hose Clamps 10pc Pack (14mm - 16mm) (FIC-14x10)

Diagram:



Return Port Injection:
Goal > 500whp

Once you get into the higher power levels you will need regulated fuel pressure "more than the oem can handle" At high boost levels you will want a boost refence fuel regulator. This will cover that. Fuel is fed through the system and regulated in the engine bay then returned to the fuel basket in the tank. You will be running a line back to the tank for return.

Items Needed:

1. In Tank: Upgraded Drop in Pump
   1. AEM E85 High Flow In-Tank Fuel Pump - 340LPH
      PART# AEM 50-1220 "good for 600+ish"
   2. Hellcat "good for 700+ish" Will need an adapter or make your own bracket
      1. WALBRO HELLCAT 525LPH F90000285 FUEL PUMP (UNIVERSAL E85)
         1. Hellcat Fuel pump basket
            
         2. DIY Hellcat Pump
         3. HOW TO: Mazdaspeed Hellcat Fuel Pump Swap!

1. Fittings
   1. Firewall - OEM Feed - 6AN Male Flare to 5/16
   2. Firewall - 6an to 6an 90 - Female 6AN To 3/8
   3. Hose - Gates 27349 Barricade Fuel Injection Hose-15' Length, Inner Diameter 3/8"
   4. HPFP - Female 6AN AN6 To 3/8 Barb
   5. HPFP - Black Aluminum -6 AN Male Thread Flare Tee Union T
   6. HPFP - Hard Fuel Tubing Fitting for hardline tube 5/16" to AN6 female thread
   7. HPFP - to PI rail - Female 6AN AN6 To 3/8 Barb
   8. Hose - Gates
   9. PI Rail End 1 - 6AN 45 Degree Push Lock Hose Fitting End Black
   10. PI Rail End 1- ICT Billet -6AN Flare to 6 Oring ORB Male
   11. PI Rail End 2 - 6AN 180 Degree AN-06 Female Swivel Push
   12. Hose - Gates
       
   13. FPR - Hyperfuel Tight-Fit Fuel Pressure Regulator -06AN 30-70PSI EFI Part Number: 493-44120
   14. FPR - 2 @ Female 6AN AN6 To 3/8 barb
   15. FPR - EVIL ENERGY AN6 Flare Cap
   16. Hose - Gates
       
   17. Fuel Basket Return - In Tank - 6an to 6an 90 - Female 6AN To 3/8
   18. Fuel Basket Return - ICT Billet -6AN Male Straight to 5/16" Barb Bulkhead Adapter
   19. Fuel Basket Return - Corrugated Fuel Hose 5/16" ID x 10" Long with Stainless Steel Vapor Clamps for In-Tank Use
   20. #16 Stainless Steel 3/8" Fuel Injection Hose Clamps 10pc Pack (14mm - 16mm) (FIC-14x10)

Diagram:


To be continued. If anyone notices any errors let me know.


FROM FREEKTUNE FACEBOOK:

 

You thief, I have a returnless guide already

 

I know I linked it you sloot.

 

In my defense I have already started drinking.

 

I think the links for 10 and 11 on the list are wrong:
PI Rail End 1- ICT Billet -6AN Flare to 6 Oring ORB Male:
https://www.jegs.com/i/ICT-Billet/335/AN920-06-06A/10002/-1

PI Rail End 2 - 6AN 180 Degree AN-06 Female Swivel Push:

 

I think just 10 is wrong it should point to The text is right though. With return less you plug one side of the PI rail. There are other ways to do it. You could have all the fuel pass through the PI rail before it ends at the HPFP which also works. This would mean no split at the HPFP. I fixed the link for 10

 

So I was reading up on this and was thinking of other ways of running a port injection setup, wouldn’t we be able to put a fuel pressure regulator on the top hat at the tank, having a line coming out of the factory feed go into the fpr and then going out of the fpr back to the line that runs to the front. And finally using the return port on the fpr to dump right back into the basket because it would be mounted right on the top hat.

I thought of this because there could be people out there that are using a returnless setup where the line coming out the firewall goes to port rail then hpfp could keep that setup because there is already a fpr increasing 1:1 with boost and returning back at the tank.

Those are just my thoughts I thought I could add, if I could get some insight on that idea it would be great


This is how I’m thinking of running the setup, 60psi rail pressure then increasing 1:1 with boost, as long as you have enough fuel pressure, I think that you won’t have a restriction no matter where the fpr is located.

 

So after using this and a few other threads to build a return setup, a couple things to note...

Returnless/Return setup:
- You can use 6AN to 5/16" quick disconnect fittings to connect to HPFP, Firewall OEM hardline, tank side OEM hardline, and tank tophat OEM plastic nipple. I used these: female 6AN to male QD, male 6AN to male QD, male 6AN to female QD
- you can reuse stock lines or make new to connect to the hardline, I reused one but tried to cut the firewall side one and messed it up, so make a new one

Returnless setup:
- MAKE SURE YOU INCLUDE POST PUMP FUEL FILER (10 micron), I don't think you can used stock filter, (plastic piece that wraps around pump has a post pump filter inside)
- I went with a Walbro pump, those are 3/8" nipple outlet, so I had to use 3/8" line in pump basket. don't use the line in the kits (he shows 10" line, that's good), it's not long enough, you want a longer one that can loop and have room to move when the fuel baket is compressed in the tank: 3/8"x10" submersable hose
- 3/8 line WILL NOT clamp down to the 5/16" barbs, I had to get a 6AN to 6AN bulkhead and female 6AN to 3/8" barb, if you know a machinist, you can prob have them turn down the 6AN to a barb and remove one set of fittings: 6AN straight bulkhead, 6AN 90° bulkhead, female 6AN to 3/8" barb
- the seatpan does not have the room for some of the taller 90° fittings, so make sure you use a 90° bulkhead above or this: 6AN 90°
- don't use the cheapo clamps in the walbro kit,it might work but the fuel line hose clamps are made to distribute pressure a bit more evenly. Pretty sure I used 10-12mm clamps for in tank corrugated line, but they BARELY fit over when loosened all the way, here's 11-13mm clamps that will likely fit: 11mm-13mm stainless steel clamps
- I bought 20ft of line and prob have 5ft left, so 15ft would be cutting it close.