Not all injectors are rated at 3bar (43.5psi). Some are rated at 2.5bar (36.26psi) or 2.25bar (32.6psi). Also, fuel injector ratings are usually rounded-off, and they may be based on actual fuel or a test fluid which may not fully resemble pump gas. Similar to engine displacement ratings, you need to take the fuel injector ratings with a grain of salt. However, the ratings should be good enough to get you in the ballpark if you at least know the base fuel pressure.

If you look in the manual you will see that the stock NA FC injectors are supposed to flow 444 to 472 cc/min at the stock fuel rail pressure of 34.1 to 39.8 psi. Averaged-out this is 458cc/min @ 36.95 psi. Assuming that this averaging is somewhat accurate, and assuming that the flow is linear, then the stock injectors would flow 499cc/min @ 43.5psi in theory.

 

Interesting, but that is assuming of course that all the things are equal.

So I'm finding out that the RX8 doesn't technically have a FPR, however fuel pressure regulation from what I make out and reading is built into the RX8 fuel pump, correct me if I'm wrong. So the fuel pressure I was most seeing was like 59 psi. Now I've seen the yellow RX8 secondary injectors rated at 380cc, which makes no since at all, and a guy sending them in to Cruzin Performance in Florida and got the results of 450cc @ 43.5psi, so logically if the RX8 are actually running 59 psi to the injectors then those injectors are putting out a possible 525cc, which to me makes it seem counter productive to what mazda was trying to do and making these cars a bit more fuel efficient. I don't know maybe I'm missing some information that is throwing my numbers off.

 

So I found a good video of what to expect from 3 different injectors, included is the Bosch Gen III (which I believe are EV6 injectors) which are still good and are only slightly lower than the new EV14s that I've looked at.

http://www.youtube.com/watch?v=7oTirEZNRw8

 

The RX-8 workshop manual shows a fuel pressure range of 54.4-65.2psi and a fuel injector volume range of 356-404cc/min for the RX-8 yellow injectors.
http://foxed.ca/rx7manual/2003mazdarx8/

Like many of the newer emissions-friendly cars, the RX-8 uses a returnless fuel system:
http://www.aa1car.com/library/returnless_efi.htm

 

Hmmmmmmm.... those ratings aren't fitting well at all with the ratings people are getting out of the yellow injectors, from one source, someone got 450cc at 43.5psi, definitely conflicting numbers.

So here's another question, how rich does the stock Series 4 Engine run? Anybody have any numbers on the stock series 4 NA engine, well as numbers with a complete exhaust, basic modifications?