so how big is too big for injectors
 

so now that i finally have 5 posts i can ask my question lol
i normally search and finally decide to post so i hope this isnt dumg because i tried to search, idk

i live in florida, own a vw r32 and a 86 rx7/87tii motor swap
now you know about me i can ask lol

i recently did the throttle body mod and noticed a crazy difference but i believe i mess up the injectors when putting everything back. it must have a vacuum leak because the idle stays around 1000-1500 and when i press the breaks it jumps back and forth.

first the car wouldnt start after, then i moved the injectors from the primary's to the secondary's and now it will pick up great to around 4000 and just kinda crap out from there, it sounds like a bunch of backfires almost like a 2 step i believe its those injectors so im planning on getting new ones.

so while replacing i might as well upgrade, i was thinking about getting the RC 1200cc but should i just get 1600cc? im on a stock ecu so would i need a aftermarket FPR to control this or what? i dont want to go all out yet, just want to finish making it run right then i will need the most fuel from the injectors, so im not looking to make 400hp yet, but eventually.

turbo back exhaust, no cat, 3' strait back to duel mufflers.
no emission control, big ass intake and maf

whoa, calm down mate, if those are your only modifications, your injectors should be fine. 1200cc or 1600cc injectors are quite large for a stock motor. If anything, maybe get them cleaned and flow tested.

and the only cars i've seen with injectors of that caliber have had an aftermarket ecu.

you don't have a computer that can properly control injectors of that size, nor do you need injectors that big anyway

well im pretty sure i broke the ones i have thats why i ask. and i plan on getting something like a power fc sometime soon. i just figure while im replacing why not upgrade. i mean if i put 1200cc in the secondarys does that mean im gonna get 80% of that in the motor? i dont need that much yet but i found that injector calculator and with 1200s i can make like 240hp right now? that sounds pretty good



well i would like it to be safe boosting 10-12 psi without running lean, so are neither of those good? maybe try to find some 680s from 1st gen.

also i was told it had the 3rd gen fuel pump when i got it

bumb.?

maybe not the injectors?
also with the trottle body mod i just plugged the coolant line from the top of the TB to the coolant line on the bottom the goes to the block. thats what i was suppose to do right?

if you did break the injectors, look at replacing them, i could be wrong, please do correct me people, but i believe the stock injectors were go up to about 250hp, or 350hp.

I'm not familiar with the TB mod. sorry for the lack of help, but it may help others to know a bit more about the engine. is it a 6 port turbo, or a proper t2 swap? (i only ask, as the 5th/6th ports create some issues as they age, not opening properly)

If you hold tight someone with some better knowledge will be able to help you out much better.

Vacuum lines have been reconnected?
i'm just brainstorming ideas now lol

Not a turbo guy but bare with me, the stock NA injectors flow enough to feed 250hp. The turbo injectors are already bigger than them so 240hp should be no big deal.

The problem with running huge injectors is at the low rpm's and idle they will be dumping too much fuel just in the process of opening and closing. You're dealing with milliseconds and the flow starts when the injector starts to open, it takes a couple to open all the way, then takes a couple more to close. You could be dumping twice as much fuel as you need in that short time with huge injectors. Pretty tough to idle with AFR's like that.

http://www.rx7.com/cgi-local/3rdgencalc.cgi

N/a's are good to about 220, and turbos maybe 240-250. you could up size your 2ndarys just slightly and run rich til you get an ecu. but its gonna be real rich with anything above a 720.

Ok. Wow. Calm down. Stop posting foolishness.
Edit: ^^^ directed@ everyone EXCEPT lastphaseofthis

250 whp on n/a (460cc) injectors won't happen...on a rotary at least.
240 whp on tii (550 cc) is a stretch and would require duty cycles that anyone who knows what they're doing would be uncomfortable w/ (@ stock fuel pressure).

Get 2 of the stock injectors cleaned/tested, put those in the primaries. Get 2 1st gen (680cc) injectors put those in the primaries. Done!

You will run rich when the secondaries come on, but its better than running lean and will provide more fuel than the stock turbo could ever use. Plus when/if u upgrade you can put the 680's in as primaries and upgrade the secondaries.

250 on 4 460's does happen, the problem is the stock NA manifold not the injectors. Just bump the fuel pressure up to 45psi. 13:1 afr's with no problem, if you want to run in the 12:1 afr range it would be tight on reasonable duty cycles.

As was alluded to by the "@ stock fuel pressure" caveat. Those statements assumed less than 2x stock pressure. Since the op doesn't have any means to raise pressure (and doesn't seem to be in a position to fool w/such things just yet) I offered the most direct solution.

I ran those mods with stock injectors and an FD fuel pump for quite some time.

as soon as you upgrade your injectors you'll need a way to control them. either piggy back or stand alone. keep it simple until your ready to invest big bucks to do it right.