injectors

[CT]

Search the big forum at http://forum.miata.net or ring powerflow injection (Victoria)- they are pretty clued up on these things as well.

[Fatty]

they are from the 89 - 92 na rx7 according to the info on miataturbo.net.

good place to get them... try ebay maybe? i got my rx7 460cc's from ebay.

remember that whilst they are a direct fit, you will need some kind of piggyback or standalone ecu to get them to work in your car, obviously.

from miataturbo.net:

Popular direct fit replacement injectors (“F” connector):

87-88 Toyota MR2 (4AGE) NA - (213cc – Beige Top)
89-91 B2220 Truck – (224cc)
Toyota (4AGE) – (250cc – Green Top)
Toyota (4AGE) – (250cc – Violet Top)
Toyota (3SGE) – (295cc – Green Top)
89-92 Toyota Supra (7MGE) NA - (305cc – Light Green Top) - #23250-70080
Toyota (3SGE) – (315cc – Pink Top)
89-91 B2600 Truck – (326cc)
89-92 Toyota Supra (7MGE) TURBO - (430cc – Black Top)
89-92 Mazda RX-7 NA – (440cc)

[john!]

So what are the biggest injectors the factory ecu can control? Or does changing the injectors mean changing the engine management?


john

[Fatty]

that one seems open to debate john, but i've got 460cc's on my car on the stock ecu, running a dfa piggyback to control the fueling. still naturally aspirated at this stage.
other people just use the injectors from the 1.8 (265cc's i think?) and add something like a rising rate fuel pressure regulator and don't fiddle with engine management at all.
then there are others who use aftermarket standalone engine management and use 550cc injectors.
so it just depends, i guess.

[Fatty]

yeah thats a good point steve.
don't even think about fitting bigger injectors unless you are putting a turbo in your car. even with the stock injectors the car runs pretty rich. i was pulling fuel with the dfa across the whole load range (except at idle) with my dfa, even before i got the bigger injectors. the only reason i have those big injectors on the car now is because i'm putting a turbo on , and i'm doing it in stages rather than all in one hit.

[john!]

Cool, interesting stuff. I am certainly a long way off getting a turbo at this point in time. I ask mainly for curiosity's sake.

In the same vein however, what sort of duty cycle are the stock injectors generally working at? Is there some sort of optimum range that you would want your injectors duty cycle to run or does that not matter so much, as long as it is not near 100% all the time?

john

[Fatty]

i think generally you want them to be operating at less then 80% duty cycle most of the time. so i'm guessing that the stock injectors are running a lot less than this apart from the occasional run up to 80% or so at WOT. depends how you drive as to where they are \"generally working at\", i guess.
apparently the stock 1.6 injectors are known to lock open if you push them too hard for an extended period of time, say above 85 % or so (generally only an issue if you're running a turbo with higher than normal pressure in yr fuel rail)
again, not talking from personal experience here.

[glen73]

Hey mate, good to see your starting doing some work to your motor. the turbo dream is now one step closer which turbo are you going?

[Fatty]

hi glen. haven't seen you around here much lately.

yes finally things are starting to happen. i have an rb20 turbo sitting on the shelf behind me, and a cheap little ebay intercooler sitting on the mantle peice in the living room. a megasquirt ecu is sitting here on the desk, and an ebay manifold has been purchased and is on it's way. i am getting together other bits to support the extra power as well. i got some bilsteins, will be getting a bigger clutch soon , bigger brakes , etc etc

[glen73]

good to hear, sounds cool. been pretty busy with work family etc. your house must look like a autoshop lol