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Discussion Starter · #1 ·
I wanna order a set of injectors and I'm confused by the "air assist" thing on Injector Dynamics website.

Can anyone confirm whether the stock 2JZ-GE VVTi lower intake and fuel rail need the "air assist" or non-air assist style injector?

Ultimately what I'm trying to achieve is to install a good set of injectors into my stock lower GE manifold and fuel rail without needing to modify anything. Injector Dynamics themselves weren't sure what part number I should order.

Thanks
 

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Yes California models use air assist. If they make injectors that support air assist, run those. Trouble is most aftermarket injector manufacturers don’t make them. If you want to run a regular (universal) style injector, you would need to get adaptors to fit them into the rail properly. I believe radium sells them. Injector Seats for Toyota Top Feed Fuel Rails

If you decide to use the regular style injectors, you need to delete/cap off the air assist vacuum line that runs into the manifold as it will cause problems.

This should be the part number for the injectors you’re after:
Injector Dynamics ID1300x-60-11-14

These need to be used in conjunction with above seats.
 

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Discussion Starter · #5 ·
Thanks for reply. My car was not sold in Cali but indeed has that air assist hose, and (what I now know to be) an air manifold that surrounds the base of the injectors.

What is the theory of operation for this subsystem?

I think Injector dynamics explained to me their air-assist compatible injectors do not retain the functionality, but rather, include an adaptor to simply interface properly interface with the lower manifold.

Still kinda confused, here...
 

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Basically there to help atomize the fuel better and to stop the injectors from “wetting” the intake port when they are spraying. It’s utter nonsense IMO. If they include the correct seats to adapt to your “air assist” rail then you should be good. You would still want to delete that vacuum hose.
 

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Discussion Starter · #9 ·
Here are pics of the injectors that were on the car.

The top feed o-ring diameter is 14mm, the bottom rubber gasket/cushion is ~23.5mm outer diameter, 15.25mm inside diameter, and 5mm thick.

Hard to say from pic, but the pic ill mannered posted above (incompatible with air assist) does not appear to have a big enough bottom gasket.

Is the simple answer here to simply order air-assist injectors?
 

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…I think Injector dynamics explained to me their air-assist compatible injectors do not retain the functionality, but rather, include an adaptor to simply interface properly interface with the lower manifold.
This is your answer I believe. If you spoke with them and the injector number you provided above is what you spoke to them about, then they seemed to have told you they will fit with their supplied adapters.

If you want to use the part number I provided above, then you will want to purchase the injector seat adapters from radium I provided.

The problem with aftermarket injectors is that hardly anyone (if anyone) makes air assist injectors. All universal injectors are 11mm top and bottom whereas the air assist units are 14mm bottoms and 11mm tops. The adapters sit into the intake ports to reduce the 14mm lower bore to accept a normal 11mm universal injector. Hope this makes sense lol.

Basically:

AIR ASSIST
Top is 11mm

Bottom is 14mm

UNIVERSAL AFTERMARKET INJECTORS:
Top is 11mm (fits GE rail just fine)

Bottom is 11mm (won’t fit UNLESS you use adapters)
 

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Discussion Starter · #11 ·
That all makes sense - but where it gets wonky for me, is the current injectors have 14mm top o-rings. The injectors themselves are RP (Rochester Products). My car was originally set up by Lance @ Toyomoto waaaay back in the day, so I assume he had to do things to "make it work" because the aftermarket support was not as good back then.

So I suspect my fuel rail was re-machined to receive an available "big" injector.

So now I'm trying to decide if I wanna order the radium injector seats and some ID1300.60.14.14 injectors... That part number oughtta jive with the radium seats and my remachined fuel rail.

Else, I could buy a used IS300 fuel rail, or I could spend a bunch more on a complete fancy radium fuel rail arrangement.

Any thoughts on what effect (if any) the radium air-assist injector seats have on spray pattern? My concern is the injector will need to spray down a small bore - and not directly into the port... So maybe the fuel will be sprayed onto the walls of the bore and affect idle quality. Anyone directly know of success stories with the radium injector seats?
 

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Pretty sure you don’t measure the o-ring or cushions for specs of the injector top and bottom diameters. Theoretically you could stretch even a smaller inside diameter o-ring over an injector and when you take it off it would measure small. Since these are 11mm injectors (inner workings throughout) the tops should be 11mm AND the very bottoms should be very similar. The stepped lower portion should be the difference where you will see 14mm as it was designed to sit in an air assist manifold. Maybe try measuring the actual top of the injector and the stepped shoulder closest to the top of the injector on the bottom?

Just looking at them you can see the bottoms (side that goes into the manifold) are 14mm. The tops (part that goes into the rail) are 11mm.

The radium seats will simply accept a smaller 11mm universal injector bottom and will have no affect on the spray pattern. You can see the very tips of the injectors will snug nicely within the radium smaller bores in those adapters. That’s what they are designed to do.
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Although now that you mention the rail might be modified, you may have to utilize whatever air assist injectors you can find that are guaranteed to work with an air assist manifold OR buy a new rail, be it stock GE rail or aftermarket rail. Stock rail should be sufficient I would think of you could get your hands on one.
 
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