Cheap injectors
 

Swiped this image from a fb group. Also a short video of the 8 injectors on the test bench (can't share that fb link). Comedy.
Denso discontinued the 425cc 195500-4450 "Yellows" from the RX8 that were so prized by BP tuners. Ebay is now flooded with cheap Chinese fakes using the same P/N and even the Denso brand.
Set of 4 Fuel Injector Nozzle For Mazda RX-8 1989-1991 2004-2010 195500-4450 | eBay

The message: don't spend all your hard earned cash on a nice turbo and built engine only to cheap out on crap Chinese "OEM quality" injectors because you don't know the difference. This is the difference.
The injectors pictured: Set 8 42lb 440cc EV1 Fuel Injectors for GM LT1 LS1 LS6 Ford Mustang SOHC DOHC | eBay

https://cimg1.ibsrv.net/gimg/www.mia...af29ce430c.jpg

We keep shouting this from the rooftops, the smart kids listen, the dumb ones still don't just to save a few bucks.

Oh snap. This explains why my OEM supplied can no longer get them easily and for a good price. Theyre buying stock from a limited supply elsewhere.


This info is very much appreciated.

Dann

This is why I only buy parts from reputable Miata vendors like the ones who sponsor this and other forums. I have not and never will buy parts from e-bay. Thanks for sharing Emilio.

is there a way to see if we have oem rx8 injectors? Do they still have the denso logo on the side?

Solution: Injector Dynamics all the things.

correct answer

What good timing. I recently sent my rx8 injectors to Cruzin performance to be cleaned and flow tested. Unfortunately, even after cleaning, they did not test well dynamically. They tested great Statically, but that isn't quite as important. I figured i would pick up a set on Ebay and hopefully with 8 injectors to choose from i could flow match 4. I purchased 4 injectors that claimed to be re-manufactured, authentic OEM Denso injectors from a US seller. I had them shipped straight to Rich at Cruzin performance to be flow tested only to try to find a match set Big shout out to Rich, he was great to deal with and I would highly recommend using him. These injectors had all the same markings as my set of RX8 injectors. Here's what we found for all you looking at Ebay for your RX8 injectors.

OEM RX8 on the left, eBay RX8 on the right

Injector resistance
My OEM RX8 injectors Tested at 14.2 ohm while the Ebay injectors tested at ~12.5 ohm

Spray pattern
Injector spray patterns were noticeable different between the two, ebay injectors had much less spread.

Static flow
My OEM RX8 injectors flowed between 424 and 430 cc. The Ebay injectors flowed between 481 - 521 cc (8% difference and as much as 22% more than my OEM rx8 injectors)

Dynamic flow
The ebay injectors actually did better than my OEM RX8 injectors here. The Ebay injectors were within about 4% of each other dynamically. However, when flowed next to the OEMs they all flowed less than my lowest flowing OEM injectors and roughly 20% less than the average flow of the OEM RX8s. You can see how terrible my OEM RX8 injectors did in the dynamic test here.

Appearance
You can see in the pictures that the Ebay injectors (right) are a darker shade of yellow the then OEM injectors.

Now these may work just fine, but as was suggested earlier, I put too much time and energy into my build to rely on what I feel are very likely Chinese knock-offs. These are going back to the seller for a full refund.

Attachment 182320
Static
Attachment 182321
Dynamic
Attachment 182322

I'm a little confused. If "dynamic" is more important, wouldn't you want to keep the more consistent set? Unless, of course, you'd rather have the wider spray pattern than consistent flow rate?

Yes i should have mentioned that I'm not using either set, I just bought Flow Force injectors to be done with it.

This is probably repetitive for most, but for those who are curious about the different tests, dynamic simulates actual injector operating conditions. Its essentially firing the injectors are various pulse widths as would happen in your motor during normal operating conditions. Static tests are just when the injector is held wide open or 100% duty cycle for a minute to measure the flow rate of an injector. Ideally you want them to be close on all these tests but its more important that they are close dynamically.

Of course, its not always as simple as that either. some injectors might be way off dynamically at low pulse widths but very close at higher pulse widths. In that case you would probably have a car that could be somewhat difficult to idle but will run well at load.

In my case, my injectors were off dynamically through various pulse widths which means that i would be in danger of having a lean or rich cylinder screwing up my AFR readings. If one cylinder is very rich and another is very lean, the wideband may show a specific AFR, but that doesn't mean that's the AFR in each of those cylinders.