About those RX7 550cc injectors.......

[goofynick6]

Turns out they're a few millimeters shorter than stockers, so when you tighten the rail down it doesn't seal up well around the head. Therefore you have a bad vacuum leak and boost leak. I shaved down the mounting point of the rail and allowed it to tighten them in better and then they stopped leaking.

Just an FYI for those going to use them on their RB20's

Nick

[rbsileighty]

Glad they work for ya... man I would have felt horrible if they didn't. Did you use the RB's rubber isolators? I wonder if using the RX7's isolators would have fixed that problem...

Thanks for the info!

[BoostFab]

Turns out they're a few millimeters shorter than stockers, so when you tighten the rail down it doesn't seal up well around the head. Therefore you have a bad vacuum leak and boost leak. I shaved down the mounting point of the rail and allowed it to tighten them in better and then they stopped leaking.

Just an FYI for those going to use them on their RB20's

Nick

good to know!! i have a set of RX7's 460cc here and i'm debating about putting them to use, it's low impedance though--i would need to get some inline resistors.

[dekand]

anyone try them on the rb25? i heard they are supposed to work fine but haven't really heard any first hand experience.

[goofynick6]

RB25 you'd need a new rail because they're topfeeds of course.

Just measure your injectors before you put them in to see if the parts where it rests against the rubber injector seals is the same distance, otherwise you might have problems like I did.

Nick

[krayton]

or go with the 850cc injectors off a FD rx7 for the rb25

(i think)

[goofynick6]

The 850's are identical size/style as ford probe 2.5 V6 injectors (220's), and drop right into a probe rail. I think that they will therefore not fit into an rb25 rail because in order to fit nissan sidefeeds into a probe rail it takes some machining.

NIck

[goofynick6]

OH yeah, they click like a MOFO! THey sound like a bunch of stuck lifters..heh.

I might wrap the rail in foam or something to quiet it down.

Nick

[BoostFab]

so are you using the Probe's rail on the RB20?

[goofynick6]

NO..haha. Sorry for the confusion, I just have a buddy with a turbo'd probe running nismo 555cc injectors in his 428whp probe.

NIck

[BoostFab]

lol, ic

[foCk]

you say "they're a few millimeters shorter than stockers," is that all you had to take off the fuel rail? how exact were you?

[goofynick6]

I took it off the two mounting points to bring the rail closer, I wasn't terribly exact.

[300Plus]

Where can I get inline resistors for a set of 550 rx-7 injectors to use on my rb25 ? ?

[rb240det]

Radioshack...or Ebay...

[BoostFab]

Where can I get inline resistors for a set of 550 rx-7 injectors to use on my rb25 ? ?

radioshackget the 10ohm ones;click here

btw! i have a set of RX7 460cc and the inline resistors for it, if anyone want it, email me.

[Valley]

ermm.. asumming low imp. injectors are 2ohm, wouldn't you need a 8ohm resistor pack? to get the proper 10ohm resistance... in a linear circuit, Rt = R1 + R2 + R3 + R4..... (however many there are)

[DustinZ]

High impedence injectors normally have a resistance value of 12-14 ohms. The stock FD secondaries are 850cc and with a topfeed fuel rail will work on a nissan motor ( i know for sure on a L28 and KA).

Dustin

[Valley]

ahh, i was curious because on the ka-t forum they had a nice resistor pack wiring how to and i believe it was 10ohms in that case. hmm... two different figures and something like this has to be right on.

[300Plus]

yeah i looked and found the link but it was down. so any info i can get please!!

[BoostFab]

all the information are posted in this thread, what else do you need(want??>)if you dont want to run the resistors, there are some rx7 injectors with high impedance...please search...it's been covered many times...

[300Plus]

it appears to be unsure of what resistors are needed. but I've got some on the way, thanks guys

[Carl H]

the needed resistors are dependent on the resistances of the old and new injectors.on my rb20 my stock injectors measured out to 13.5ohms while my new ones went out to 2.5ohms, there for i needed idealy an 11ohm resistor to compensate, but since there isnt one 10ohm 10watt ones worked for me.ebay or radio shack i got mine off ebay for stupid cheap and got 20of them.

[BoostFab]

it appears to be unsure of what resistors are needed. but I've got some on the way, thanks guys

just go by what i post above and what carl said...don't get distracted by valley's false assumption.

[300Plus]

thanks guys. I'll keep you posted

[Valley]

what false assumption? the resistance of injectors does have to be right on or your risk damage.

the reason i questioned the 10ohm resistor is because i had read on the ka-t forum that they needed 10ohms total, i didn't know what the rb's needed nor have i ever said i did. but until carl posted his most recent post in here it all looked like speculation to me. get it?

[DustinZ]

when the ka guys said they need 10 ohm total, it is because you can put a 10 ohm resistor on the common feed line and all the injectors will messure out at the ecu as high impedence. There are 550cc and 850cc high impedence rx7 injectors that do work fine. They will have to come from a 1987.5 to 1991 turbo for 550cc, 1987.7 to 1991 NA for 460cc, and the thrid gen 1993 to 1995 have 550cc primaries and 850cc secondaries.

Dustin

[foCk]

Instead of sanding down the fuel rail you can use MKIII Supra injector isolators instead of the Nissan ones to seal against the intake manifold

[300Plus]

so it seems everyone thinks they will seat properly on the rb25? just not the rb 20 right?

[goofynick6]

High impedence injectors normally have a resistance value of 12-14 ohms. The stock FD secondaries are 850cc and with a topfeed fuel rail will work on a nissan motor ( i know for sure on a L28 and KA).

Dustin

The FD 850cc secondaries are side-feed injectors and won't work with a top feed rail.