Eyeing injectors for my 1995 NA8 with FM turbo kit. Looking for large enough to support 250rwhp which an online calculator suggests around 530cc at 85% DC.

Aside from tuning, are the following OEM injecors truly "plug-n-play (no wiring, no spacers, etc)?

89-92 Mazda RX-7 NA 440cc - Blue Top #195500-574089-91 RX-7 NA 460cc - Red Top #195500-201089-91 RX-7 TURBO 550cc - purple top #195500-2020

Do newer injectors have a technology benefit over these from the early 90's?

 

Full stop bud. 90's injectors are trash compared to anything modern. Just eliminate the brain damage and get yourself a set of FF640s or better yet an appropriate PnP size from InjectorDynamics (yes they are absolutely worth it).

And please for the love of God stay away from the inevitable yellowtops all the morons will tell you are OK. Anybody who says "yellowtop-no issue" should be scratched from your list as a reliable source of information.

 

I wish I went with Injector Dynamics for that sweet injector data (small pulsewidth settings).

 

I was looking at the ID1050's but have concerns about poor idling due the injectors being waaaay too big. Are my concerns unfounded?

Also I read they don't fit an NA8; the connectors hit the housing or intake manifold and need spacers at the bottom which screw up the spray pattern. Again, happy to be corrected here.

The cost of the ID injectors isn't a show stopper if they install well and don't affect idling and drivability.

 

I haven't been here for a while, but I had the best of luck with the RX-8 425cc yellow injectors. They responded like factory miata injectors, but obviously could support more fuel.
Quick search gave me this:
https://www.google.com/search?q=rx8+...hrome&ie=UTF-8
Most likely won't support 250whp though...but I can tell you...I ran em in my car and it dyno'd at 225whp and was a genuine BLIZZAST.

 

Looks like both Goodwin and 949 sell the IDs, I say give them a call and ask them directly about the NA8 fitment.

As long as you are on an MS3 or better ECU that supports SSPW, idle should be fine. The 1050X is amazing. The FF640 isn't quite as good, but still have a good reputation and will allow you to use more DC.

Your power goal is a trap for many enthusiasts, moar is frequently needed.

Edit: looks like FM sells a FF725 with tighter matching. It does use an adapter, but appears to be on the rail side. I have found FM to be pretty selective in the products they sell. They are also great with support.

 

RX8 injectors haven't been reliable for years now, they're either old and shitty, or "rebuilt" and shitty. Endless popping, uneven fueling, and leaks, to name a few issues. The shop I work at won't tune (aka, I won't tune) a miata that comes in with RX-8 injectors.

Yes, they're unfounded.

You're not using the full capacity of your injectors at idle, no one is. Your car makes....1hp, maybe, at idle. Use an injector calculator, and even at 10hp it'll say you only need 15cc injectors.

My point is, it's not highest hp the injectors are capable of that's important, it's how well they're designed to flow at low rates. Older injectors suck at lower flow rates. When you could get decent RX8 injectors, they usually needed to be flow matched, and then they'd idle around 14-14.5. If they weren't you usually needed to target 13.5ish or even richer.

I've tried DW, RX8, FF, and ID injectors, and I'm sure some others. IDs are BY FAR the best performing injectors, I have zero issue targeting 14.7, and I'm sure they'd operate even leaner if I wanted. They're small pulsewidth data is probably the main reason for this, they provide this data for most of the popular aftermarket ECUs, including Megasquirt, and the Link I use, among others.

Flow Force is a close 2nd, they're injectors are a similar industry standard Bosch unit to the IDs, but they don't provide the same small PW and deadtime data, although with the price savings and help online here, they're still a great purchase.

 

Are Grams injectors any good? https://www.good-win-racing.com/Mazd...t/61-2655.html

Hard to look past the ID injectors having good tuning data. I remember not having good data as a handicap when trying to tune aftermarket injectors on my LM7 with EFILive.

 

The RX-8 "yellow" injector are Nippon Denso and went out of production like a decade ago. The bulk of what's being sold new now are Chinese fakes and just trash. If you can get your hands on of genuine Denso's, service them and go. But they're small. OK for low boost on gas or high power N/A. But med-high boost on corn will need a bunch more usually.

Josh is right on the ID's. Exemplary low pulse width performance. You can get their much bigger injectors to idle like stock on a bone stock engine.

 

I'm on the FF725 from Flyin Miata. Flow force work great.
Just be aware that there isn't any official small pulsewidth setting data on them and idle area needs EGO 25% authority to deal with injector heatsoak.
I don't know if ID's also experience the same.

I've been obsessively playing with small pulsewidth settings using the ID725 settings as a starting point.

 

Emailed goodwin about ID1050 fitment in an NA8 and they basically said it's hit and miss, you have to ticker with them to clear nearby things...