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Stock Injector Flow Rate - Real Number?

Member Admin

As some of you may have noticed, I am now selling FIC fuel injector kits.  And I also bought a kit of 650cc injectors for my project.  The best part about these kits is that they come with full stats on each injector and coded to their serial number so I know exactly how much each flows and what the latency is for each one.

So yeah, that's fantastic.  However, I need to factor in my sizing percentage for the PFC.  And the actual flow rate of stock injectors (as the PFC reads them) has been debated forever and I don't know if there was ever a final number posted.  Here's the info I have accumulated so far:

Stock injector sizes:

  • 255cc Published on Denso website and in other Toyota literature
  • 260cc A number floated around by some other people back in the day on that other forum we used to be on
  • 270cc Another number that came from some people on the other forum.
  • 290cc The number Apexi in Japan claims the stock injectors to be
    • Was there a difference in JDM injectors vs USDM?

The main question I have for those that are still actively tuning with a PFC and have different injectors is "On which stock flow rate are you basing your conversion?".

Here is my thoughts on the subject at this time (Don't let this taint your replies, please):

  • The injector size is actually 255cc
  • The PFC thinks the size is 290cc
    • But the maps simply accommodate for the difference since it's tuned anyway.
  • I based my HASS White injector sizing off of 260cc since that was popular belief at the time

Result?  I'm torn between 255, 260, and 290 for different reasons.

  • 255cc because that's what I believe the actual flow rate of the stock injectors truly is.
  • 260cc because that's what I was using before and I likely will have to do less scaling in my new tune (most lazy reason)
  • 290cc because that's what Apexi thinks the stock ones are and my maps may be more better somehow.

I would love some of your thoughts on what my options are and if there is another size that I didn't list.  I'm still a long way out from doing any of this tuning, but progress is being made each weekend towards the goal of the car running and moving on its own again.  🙂


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Topic starter Posted : March 10, 2022 10:52 am
CSPIDY reacted
Estimable Member

My thought is....

 It doesn't matter. Achieving your AFR's on your unique setup does matter. Getting in the neighborhood with 255 or 260 is close enough that the minor adjustments will just get you closer to where you want to be a little sooner. 


Another thing I just thought about, Way back in the day, I had 660cc injectors, but because of our fuel pressure I had to adjust my maps as if they were 800cc. So maybe that's why Apexi used 290.

Posted : March 15, 2022 2:31 pm
Member Admin

Interesting...  I'm still a long way away from tuning.  But this helps.  Thanks for the trip down memory lane.

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Topic starter Posted : March 15, 2022 8:29 pm
turbo_jimbo reacted