New injectors needed, upgrade to 680cc? - NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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New injectors needed, upgrade to 680cc?

Old 01-22-2002, 02:25 AM
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Hey guys, for all that don't know me I have a 87 TII with bad secondary injectors. As I was pricing new injectors i came across something intresting. 680cc injectors will bolt right into an 87 TII, hence giving it more fuel. I also read one can get these injector form the older 84 or 85 GSL-SE. As i looked deeper into i came across mixed feeling on if it was turely an upgrade. What do you guys think? One guy said that they work great when your pushing you car, but the problem comes when you don't give you car the proper ammount of air it needs while injection more fuel. Hence running it rich. I interpurt this as driving your car at higher RPMs without pushing it,.....so to speak (i.e. crusein down the highway at high speeds) Is this guy right? What do you guys think, should i upgrade, or stay with my 550cc.



Remeber, i would only be upgrading the secondaries,....wait a min, can i have primary as 550 and 680 fro secondaries?
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Old 01-28-2002, 03:52 PM
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What mods do you have? The 680's will work better if you have a Super AFC.
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Old 01-28-2002, 05:55 PM
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This all depends on your current mods....if you have full exhaust, intake, UD pulleys, and ignition...then upgrading the injectors and using a S-AFC to control it all would be a great way to get better performance....
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Old 01-29-2002, 01:30 PM
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As long as you keep the rpms under 3800 rpms, the secodaries stay shut. That how they work on the stock ECU. If you have upgrades like downpipe and intake you can get them.



You have to becareful to match impedence requirements.

If you have a pre 87 1/2 rx7, then you can use the bigger injectors with no problem since the impedence match.



If your rx7 is 87 1/2 + you will have a problem matching the impedence since the ecu uses high impedence and the gsl-se are low impedence. You'll have to use resistors to make them work.



C
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Old 12-29-2003, 11:16 AM
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im most likey gona be doing what this guys doing . how can u tell if your 87 is low impedence ?
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Old 12-29-2003, 11:59 AM
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if you do an intake/exhaust mod, definately go and try to get some bigger secondary injectors. because they only turn on in the turbo2 after the turbo is already spooling, it will ease worries about over boosting and running lean, causing a blown motor. i dont' know if the used injectors from an old rx7 would be the best. Rx7's are known to be plagued by leaky injectors. ur best bet would be to get some new ones. check the sponsors on this page, or check out www.srmotorsports.com
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Old 12-29-2003, 06:05 PM
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get the secondaries along with a cheap MBC of ebay. tune your boost to start at lower RPM's, then with some creep you should even out.



tell me how it works. i'm creeping up to 11-12 psi, and i've added walbro 255 fuel pump. i dont wanna blow up, so i might go with these 680 secondaries.
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Old 12-30-2003, 04:46 AM
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www.srmotorsports.com they want 155 each for 680cc injectors u can get them off a gsl se frist gen for 80 to a 100 dollars then send them out to rc for 25 dollars to get them cleaned .
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Old 12-30-2003, 04:38 PM
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they would perfect on series 4 t2's.. my neighboor with the t2vert.. uses them with a bosch fuel pressure regulator and a fd fuel pump. very big street port. and his car never leans on top end..with an s-afc of course it be better because u can fine tune to a certain point... but 680cc's is cool if u cant get 720cc's...
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Old 12-31-2003, 04:44 AM
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if u have a fmic ,680cc injectors and fd fuel pump rewired how much boost can u run being safe ?
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