$10 says the OP is running unreferenced and trying to make 350whp with ~40psi of differential fuel pressure.

While it's cute of you to call me out, the fuel pressure required to get there on 1300's is higher than I'm comfortable with. Differential pressure of 60psi at 25psi boost is 85psi rail pressure. No thanks.

FPR is boost referanced with base pressure set at 60psi. fuel pump is rewired and running off a HYdra 2.7 with Flex fuel sensor and full an lines to FM dual feed rail. Im pretty sure im getting enough fuel to the rail as what I have found this system can flow a bunch of fuel. I did some research and found the FM's mule car for Flex fuel was maxing out 1000cc injectors at 80% duty during a 430hp run. Wish I new this before ordering 1000cc.

Injector Dynamics website has data that said at 107psi the 1000cc injectors can flow a max of 1300cc.

Or doesn't have enough fuel pump and fuel pump wiring.

wait, how is 80% duty maxing out the injectors?
pretty sure its 97% duty for full-sequential @ 8000 rpm.

ID says their injectors atomize ideally at ~90psi. Max allowed pressure is downright silly, something like 120-130psi IIRC. Anything lower than 90psi and you aren't getting the full benefit of their spray pattern. I had the same reservations when I built my E85 turbo car 5 years ago, and a quick phone call to ID put them to bed. I ran ~85psi of rail pressure on that car for over a year with no issues (70psi+reference).

No call-out intended, just correcting something that's obviously incorrect. Don't get your panties in a wad. :party:

Sheeeeeeit. I run 80psi of rail pressure through some old EV1 Supra 440s, been doing it for 2-3 years. Not a single fuck was given.

Thats the quote from the Youtube video.

As from my research and from working as a auto Mechanic for 15yrs you never want to see a injector running to full duty cycle. So technically 80% might be maxed out for safe reasons.

My injectors are running 100% duty durring data log. Boost referanced at base pressure of 60psi.

RC told me the max allowed pressure on my RC750s was 65psi. I lol'd and put them up for sale that afternoon. :party:

Pump, no. Wiring, possibly. I still have a hard time with that, though, since IIRC Soviet didn't see fuel pressure drop until 25psi and north of 400whp. That 5psi of pressure makes a big difference in the current required to run the pump.

e: Flex fuel sensor should be fine, it's in the return line as-delivered from FM.

I would have taken that to mean "at the nozzle" and immediately set out to see what happened at 65psi base.

I plan on running the RCs i'm chucking in this time around to 80-90psi rail pressure at TEXAS% duty cycle. What's the worst that can happen?

I guess it has gotten a little off topic as I am just wondering if 1300 cc injectors wil be enough with some head room or if I just need the 2000cc. Ben I do believe answered this with the 2 stage set up question. Just wanting to verifiy on that at 500+ hp 2000cc are required unless running 2 sets of injectors. i would tend to lean towards the 2000cc as long as people have not seen idling or low rpm no load problems with this large of a injector. The intercooler im still wondering if i need even larger then the 600 or 550 for again safe margin for track use for intake temps. Im leaning away fromt he precision do to the high pressure drop.

Again thank you all for any help given.

Eh. 80% used to be a good rule of thumb for injectors that required long dead times to open (EV1, etc), but with the new fast-acting EV14s, you can safely run them up to 90%. It actually varies with RPM, as Soviet mentioned, since the max allowed DC is engine cycle time in milliseconds (time it takes for the crankshaft to rotate 720deg), minus the dead time of the injector. Old injectors required 1.2+ms of dead time, but a good EV14 is closer to 0.6ms. When you're spinning the crank once every ~8.5ms, half a millisecond matters.

As long as you can get the injector fully closed before the ECU commands the next pulse, you're good to go. ID actually issues a chart that does the math for you.

http://cdn.shopify.com/s/files/1/022...Duty.png?32193

If it is true that they want to see 90psi i have no problem bumping my base fuel pressure. However, based on them being maxed at 100% duty already at 18-19psi. im not sure this is going to solve the issue of not enough injector. I will be running more pressure with whatever new in jectors I get.

Im just worried that 1300 will not be enough and I dont want to buy 2 more sets of injectors.

You don't understand how injectors work. More fuel pressure results in more flow. You are maxing out the injectors because in the duration of 4 strokes the injector can only inject that much fuel. If you raise the pressure, it can inject more fuel. The difference between 60 and 70 psi is 7% extra flow.

I'll buy them from you at a discount :)

I'm not worried about the injectors; I was thinking of the rest of the fuel system. My level of comfort on certain things has grown more conservative over the years. Yes I've gotten away with it in the past, too. I've also seen a couple cars burn to the ground.




The injectors are maxed out when increasing values in the VE table does not affect air/fuel ratio. With older style injectors, that tends to occur around 80%. Newer EV14 injectors can be run to 85%, possibly higher.
For the record, I have a set of ID1300s en route to play with.

1300ccs should be more than enough injector, but the problem is that you shouldn't be maxing the 1000s you have with your fuel setup. Adding 1300s or 2000s now would be a bandaid on internal injuries. Others have done exactly what you are trying to do (450whp on E85 with ID1000s, 60psi base + atmosphere reference), so there's no reason you shouldn't be able to do it too. Do you have fuel pressure data at high RPM? Any idea how much power the car is making at 19psi when you're running out of injector?

Currently the stock 5speed. Have not decided on 6speed as they are not reliable at my level. Quafe 5 speed sets I guess break at this hp level as well. Kind of waiting for someone to do the leg work to figure out a t56 or t5 swap. Its got a 3.9 torsen from a 01.

Hmmmm...Maybe I'm retarded, but I grenaded my five speed on much MUCH less power....

How in the hell are you running what sounds like 400whp through a 5 speed and a 3.9?

Please dont take this the wrong way. I do know how injectors work as I my job is to diagnose drivabilty problems every day at work. im a advance level diagnostic automotive technician and have been doing it for 15yr. I currently own my own shop and all i do are the hard diagnosic jobs that dont pay to keep the rest of my employees at 120% effiancy.

i know fuel pressure directly relates to flow of an injector. im worried that with what i would concider to be a safe level of margin for fuel pressure which I guess is 90psi according to savington is what ID's want. im ok with that.

As far as duty cycle yes they are ok at 97% at 8000 rpm according to the chart but that is it. im not ok with that. i want to see some slack. again. I dont want to buy 2 sets of injectors if i decide to madify something else. IE custom intake or larger turbo. buying 2 sets of $950 injecdtors is not on my list of enjoyable spending.

The 1000s will be up for sale.

I don't think you're understanding. Nobody is saying that for whatever reason you AREN'T seeing 100% duty cycle, we're just trying to figure out WHY.

How much power are you making?

Please don't take this the wrong way, but it appears you are completely full of shit.

Many on here are certified techs, also many others are business owners. (I happen to be both).

You're grammatical errors, along with some other statements made make me think you are not as qualified as you say.

Best of luck becoming the first 600 whp miata that uses a stock 5 speed.


P.s... The leg work has already been done as to retrofitting stronger transmissions..Maybe you should look into them more.

P.s.s. Before the obligatory excuse about being on your phone..this entire response was sent from one.