EA SPFI injector flow rate info

[Crazyeights]

Had a friend flow test a standard Subaru SPFI injector and a Nissan D21 Truck injector (physically fits the Sub Hitachi SPFI)

 

Injector #1 Stock Subaru (Part Number JH45-1)

1F@20PSI = 133ml

800cc or 76pph

 

Injector #2 Nissan D21 Pickup with a 2.4 (Part Number JH50-1 2 required)

1F@20PSI = 113ml

688cc or 66pph

 

I didn't have a Nissan VG30 injector (Should be part number JH40-?) for him to test but I bet this is the one we want. It should flow about 18% more than the stock Subaru injector. He will run the numbers on that one for me if I can find one.

 

Just FYI because I didn't see this info anywhere out there.

[GeneralDisorder]

Very useful! I have never seen that info before. Could be very useful for MegaSquirt type work. Good to know the D21 injector is not an upgrade - strange though - aren't those engines larger?

 

GD

[Crazyeights]

It seems that the D21 with the 2.4 uses (2) JH50 injectors with a lower flow rate than ours (JH45). The Nissan Pathfinder or Pickup with the VG30 6Cyl should use a pair of the JH40-? injectors which should be an upgrade for us if our math is correct. In the Subaru SPFI the Nissan JH40 injector should run about 18% more fuel at 60% duty cycle.

 

I am trying to find one to test and also have him flow it for me.

Edited October 9, 2010 by Crazyeights

[84gl]

I ma running a VG30 injector and have been doing so for three years It was the only way to fix the top end flat spot I had after the motor work was done and before megasquirt My Built ea81 didn't run right with the stock spfi it just didn't get enough fuel which I found discovered while playing with a wide band o2 senser basically it started running lean around 3500 rpm with the stock injector so I hit the books looking for what would interchange which are the nissan spfi injectors all models 86-94 4 and 6 cly. pickup And suvs some Izuzu pickups depending on if they were Hitachi or not

 

What I found out was that the stock spfi with stock ecm is only able to run around 110hp engine after that it starts doing some weird stuff like idle hunting and fuel cut it did this with three ecms so they weren't bad and I checked the harness pin by pin too. If you go with megasquird 2 they make adapters to plug your megasquird ecm into your stock harness so most of your wiring is done already. The wall I am running into is the the flow throw the throttle body intake and heads. They have pretty much limit you to around 130hp and thats with my jdm dual port or dual carb heads I would have to say that with US market big valve heads your stuck around 120-125hp and thats with spfi pistons shaved heads a cam oversized valves and a port and polish job.

[Crazyeights]

Update. Instead of finding the correct Nissan injector I opted to bump the fuel pressure by a small amount and it works great! The spec for SPFI fuel pressure varies between 23-45 lbs and the stock injector only runs at about 60% duty cycle so there is some room to play with. My system ran right at the minimum of the spec (23 psi) no matter what I tried (multiple SPFI assemblies, fuel pumps, ect) unless I deadheaded the system for a max pressure check. With the return line temporarily pinched off the engine ran noticeably better and the pressure went to about 60 psi - too much pressure and no return path.

 

Here is how I did it on the cheap:grin:

 

Here is the adapter in my fuel return line

 

Cut threads on the inside of the larger nipple like this, I used 1/4-28

 

Find a bolt that will thread inside

 

The next step will take some time. Find the right size hole to drill in the center of the bolt to bump the fuel pressure by about 10 psi, I ended up at 7/64 I think.

 

 

Cut the drilled bolt off and thread it inside the pipe nipple with Locktite. Double check your fuel pressure afterwords one more time.

 

 

It REALLY WOKE UP my performance built SPFI EA81. The engine has felt lean ever since I built it. Now both cold and warm drivability are vastly improved and it pulls pretty hard right up to 4500 RPM with no sign of stopping there. I also bumped the ignition timing from 20 up to 28 degrees. Make sure the EGR is hooked up and working to keep cylinder temperature down and pre-ignition from occurring. The engine is just out of break-in so that's as far as I care to push it for now. I don't know if it would make any difference at all on a stock build.

 

Hope it helps!

Edited October 23, 2010 by Crazyeights

[Txakura]

This is awesomely good stuff, I have always wondered about the SPFI injector but could find very little on it, some posts were too vague to get any answers (apparently). I'll watch this for any updates you make, great job researching and trying some new ideas - and POSTING it so other folks can see it.