This isn't Miata relevant, but I haven't had any luck finding answers and I'm thought someone here might have some insight (that I valued more than someone on a Honda forum).

Apparently 270/310cc RSX/CRV/Civic/Sentra injectors have a screen over the tip of the injector. When the screen is removed the injectors become 490/520cc injectors. People have flow tested the modded injectors with positive results and Comptech (very reputible Honda aftermarket company) even sells the modified injectors: High Flow Fuel Injector (K-Series Engines)

I'm curious what the purpose of the screen is? I can't imagine the manufacturer just adding it without some rational behind it. Is it just an emissions thing? I have to think it affects the spray pattern/atomization at the very least. Everyone seems to report positive results, but I'm still nervous about it. I'm curious to hear other thoughts/opinion/theories on it.

Thread with pics and flow testing:
Modded OEM 270cc injectors = 490cc - Club RSX Message Board

Left: Modded, Right: Stock


How to modify SE-R 310cc injectors:

 

Its possible that the injector company already made 500cc injectors and needed a 300cc injector yesterday with an engineering budget insufficient to pay even an intern so they came up with this on lunch break, saved a **** load of money and got zero credit for it.

 

I would guess the following, or maybe some combination of them:

A. Finer atomization of the fuel droplets

B. Screen changes the spray pattern giving some desired spray cone shape / distribution at a very specific distance from the tip of the injector.

C. Screen improves emissions through some black wizardry (See A + B)


In the OEM world, emissions is generally KING.

The people that have tested these and report good results, what kind of good results are they getting? The good result is that they are able to create a higher flowing injector for free, and are still able to control their AFRs? If that is their only goal, then maybe they are getting good results.


TANGENT:

In my experience the stock Honda injectors aren't very good, at anything really (other than being cheap). Similar mods can be made to Bosch EV14 injectors (how do you think the ID1000s are made?) with even better results. What I mean is you could get a set of Bosch EV14 off of a pentastar v6 for basically free at your local junkyard, remove the plate on them and voila, 500+cc injectors that are EV14s and way better then stock Honda/Nissan injectors.

Or think of it like this, by "modding" the injector you are likely sacrificing some level of atomization/spray/pattern/etc. in return for higher flow. If you start with a chitty injector and then mod it let's say you get a slightly worse, chitty injector that flows a higher cfm. Start with a much, much better injector (Bosch EV14) and then mod it, you will have a slightly worse, much, much better injector that flows a higher cfm.

IE modded EV14 >> modded EV1/EV6

People should start scouring junkyards for Pentastar V6 injectors and see how cheaply they can get them. Unfortunately they are the "short" version of the Bosch EV14 but it shouldn't bee too much work to adapt them to your average Honda/Nissan/Mazda fuel rail and IM...

 

"Good results" consist of several cleaning/test results like:



and every review I've seen read was something like, "Dude, this is so sweet and it's like totally free dude, my car pops vtec so hard now."

 

Hey guys, rather than re-engineer an injector, lets put a screen over it to reduce flow AND increase atomization! WINNING!



Haha, I doubt it went down like that. Honda is not exactly known for cutting corners on OEM hardware development. I would expect the above from GM or Kia or something, but not Honda.

 

lol @ the hack in the video. He did everything but whack the injector with a hammer. I don't know what he took off but it was amusing watching it being done.

 

This reminds me of back in the day when modifying subaru injectors was all the rage. Like 06-07. Then cars started blowing up, then flow reports showed that this is about as consistent as pissing in the wind, then people realized there's a reason why aftermarket companies charge good money to modify injectors for you.