I'm pretty certain I hit 200whp on my stock 99 injectors.

Both begi and flyin miata say the stock 99
Injectors Max out there. If that is the case the RX8 425cc injectors should Max out at around 325 on gasoline or 250 on E85.

Thanks,

Keith

I'd kinda worry about 250 with e85. After hearing some testimonies on these injectors, I think they'd be fine with pump gas. I've never tuned with E85, but I hear it requires a LOT of gas. Might wanna consider an adjustable fuel pressure regulator, or larger injectors.

That's way above what RX-8 injectors can do. I'm capped at ~200 hp at crank (!), running around 90% duty cycle @ AFR 12.2. And yeah, that's E85 with stock fuel pressure.

What fuel pump are you using and is this on an NB running 60 psi of fuel pressure? Last dyno session I made 200whp and I was running pig rich. That was on "winter blend" E85 though (E70).

Keith

Nope, it's NA with 43psi (?) referenced fuel pressure regulator. NB 60 psi regulator is not referenced to manifold so i guess they are effectively the same at 7 psi of boost i'm running.

hi, all

Since there was only one person that has replied on a topic that has experience with these injectors i will ask again

Today i picked up a couple of yellow 4450 ones. And a few hours later i got a mail that some has a couple of purple 4460.. At first i was looking for this one but the rx-8 model that has these injector where never imported to the netherlands. So i gave up searching and picked up de the yellow ones.



Does anyone more has experience with these 4460 purple ones?

Nope.

I was shooting for around 260whp, glad to see I picked injectors that will be suffice.

Is your FPR a 1:1 ratio? That is what I am used to on turbo mitsubishi's. Yeah, at 7 psi of boost you would have around 50 psi fuel pressure, keeping the differential pressure between the fuel rail and intake manifold at 43 psi. Since mine is not referenced to manifold pressure I would still have 60 psi of fuel pressure, and the differential pressure between my fuel rail and the intake manifold would be 53 psi. It may not be a huge amount, but a 10 psi pressure difference will make a difference in how much power you can make.

Keith

Bringing this back to get some input on my build. See Se Post 102

I would think I should be at those kind of power levels at 80% DC on these injectors. I know both @Savington and Emilio have also used them in the past.

Note that I have gone to a return-style fuel system.

Should I be looking at the DW100 or DW200 to replace my fuel pump?

I ran an experiment this morning. Nice and cold, so already 1% more fuel requested due to MAT Corr. Then I changed the target AFR from 11.7 to 11.4 (Fueling is "Incorporate AFR")

Ran full pedal. IDC went to 108%. At that point, Target AFR was 11.4, but Measured AFR was 11.9. I'm pretty sure I'm no longer controlling fuel.

So, for now, I'm backing down max boost at high RPM so that I'm at least below 100% IDC.

Question remains: Would this be helped by a new pump or not? Or am I at the limit of the Yellows with 3-bar, MAP referenced fuel system.

What pump are you running? I can tell you I'm seeing fuel pressure drop at 6 to 7psi or roughly 175whp. I'm throwing in a walbro 190.

Original Stock with 95k miles.

I've pretty much decided to back down from 194 to 188kPa, which gives me 96% Inj Duty Cycle until I have the car properly dyno'ed, which will be who knows when.

I guarantee you that your fuel pressure is dropping off substantialy. You are out of fuel pump capacity by a large margin. To complicate things it's not like your fuel pressure will drop off consistently every time you go WOT, battery voltage, temperature, ECT. Will all affect how much the pressure drops off so you will see large variations in pressure. I wouldn't​ continue to run the car at these boost levels until you get a pump.

From what I've read you'll get so.e pressure creep at idle with any pump larger than a walbro 190. The 190 will easily support 300whp, so there isn't a good reason to run anything bigger.

I don't know if "substantially", but that does seem like root cause. Following is an un-tuned pull after putting in a DW100. Looks like I have about 10% more fuel available at the top end.


https://cimg5.ibsrv.net/gimg/www.mia...7b2cb13f60.png

Also, idle and cruise did not change, so that indicates that indeed, the DW100 does not over-power the FPR (1999 European MAP referenced).

10% is a nearly a full AFR point, so tOmato / tomAto.....It was quite a bit.

Considering the dw100 flows 165 lph it won't over power the regulator. I just swapped pumps to a walbro 190 because I was loosing pressure at WOT and found a 255 walbro in the tank, I'm running a fuel pressure sending unit and saw a 12 psi drop in pressure at high flow conditions. It was rocking up to 74psi at low flow and dropping back to the NB 62psi at wot. I just thought my sending unit wasn't calibrated, but ends up I had the opposite issue that you did.

Glad you got it fixed.

Good Point. 10% at that level is another 20 HP, potentially. And yes, it was a full AFR (10.7 vs 11.7) and at 90% DC while achieving that.