RX-8 Yellow Injectors 107 DC, 12 Psi TD04
 

Just wanted to ask a question, currently running my TD04 at 12 PSI on a 1991 Miata with stock fuel pump and stock regulator. I just put in RX-8 yellow injectors and they are hitting about 100 ish duty cycle and I have the log for it as well. I was wondering if this means I need a new pump or regulator because I thought these injectors would be able to handle that. Attached is the log. https://www.dropbox.com/s/46on6p55g4rewv9/dyno.7z?dl=0

Where did you get the injectors? why do people still try to save 200 bucks on injectors....FlowForce are like 300 bucks and are flow matched, real injectors.

Bought them from someone who was upgrading their injectors on their RX-8. A bit out of budget to get flow force injectors for me.

Likely fuel pump. DW100 is recommended, but with stock (OEM) sock.

a quick trip to the injecor calculator shows that at 250 crank hp you are needing about 430 cc @90%. so you are probably maxed out.

Gotcha, I will be ordering one tomorrow then. Pretty sure this is the original 25 year old fuel pump still haha and fuel filter so I will order one of those too.

So you think I'm making about 250 HP at this level? I honestly have no clue what type of power output I have currently. I ran a virtual dyno that said 150 HP lol.

No idea. google it. I was thinking you had a 1.8 which would be plausible, but now I see you have a 1.6

Well its fast but definitely not that fast, full throttle doesn't spin the Daisy's in the rear in first gear. Yeah I have a 1.6. I did beat a 2014 WRX from a dig however so I'm not sure what range of power that would put me in.

Assuming TD04L-13T, In doubt OP is at 250 even at crank at 12psi.

That calculator only works if you're AFR's are in line and your burning all the fuel at the right time (timing) all that factors into the BSFC part of the injector calculations.

Yeah I'm not sure on the exact spec on my TD04 but its not huge its kinda small. But I will be replacing that pump this weekend. Any huge dangers on running it like this for now?

yeah, so assume less than optimal afr(rich) and you are probably at or near 100% duty.

You need to keep an eye on AFR's, they get erratic as you near 100% duty and there is no float left to cover cooler air temps or a multiple of other factors that change fueling needs. It's risky and any good tuner will tell you it's a bad idea.

Alright I will probably be turning my boost down to 10 or 11 psi for now. But I will be keeping an eye on the AFRs, it is currently hitting my targets fine, I have it at around 11.5 towards the end. It is not leaning out currently.

However do you think a fuel pump would help me out with this issue? Because I'm pretty sure I'm not at the max power level that these injectors can handle.

You'll spend enough on a fuel pressure sensor to know for sure as you would on a pump. A DW100 or a walbro 190 will cover you and not risk being too big and overrunning the FPR. With that said, I'm guessing it won't help but it's good idea to replace the pump to be sure.

it would help you only if your stock one isn't working properly
if you didn't dial in the injectors properly, then the IDC's, which are calculated using that info, are nearly useless. in which case there's no real way of knowing if they're maxed aside from eyeballing afr's

when testing my msm, the stock injectors hit something like 135-140% IDC before the car started to lean out. lol

Yes I still have to get my injector dead time correct and calibrate them right, I simply have it setup to where It idles really good. However it does seem that they do not go lean at all. Before I tuned so that they weren't so rich in boost I was hitting 10.0 AFR and they were not leaning out there at full boost. So I think I have to work on the calibration some more, but regardless I will be getting a new pump. I also need to calibrate the voltages for my battery as well and the dead time.

This should have been done before you even started the car. why did you not do this first?