88 s4 t2 rx7 injector question
 

hey guys i dont know if it matters or not but here goes:
Does it matter if i have bigger injectors in the secondary and smaller in the primary or do you want it the other way around or all the same or what? Any advice would be greatly appreciated, as im new to the t2 world im a na guy. Thanks

if its a stock setup leave,em be.

Basically....resolution is linear with size. Smaller injectors (ie: 550cc) have better resolution than larger injectors (ie:1600cc). Smaller injectors are used to give a smooth idle because they are easier to control. Small injectors would be used for the entire rpm range but there is a trade off between control system cost and packaging. Larger staged injectors that work at higher rpms is the compromise.

Real basically...if your car is running right don't f*ck with it.

This book is a good read. The chapter on EMS tuning is the best chapter. I wore out my first copy:
http://www.amazon.com/Modify-Managem.../dp/0760315825

This one was also worth the money:
http://www.amazon.com/Induction-Perf...6&sr=1-3-spell

from the factory all the 2nd gens had same size injectors in primary and secondary. the FD had larger secondaries.

thanks for the help guys. Ok well i just got a t2 engine and it has lucas 720cc injectors in the secondary but none in the primary so thats why im asking. all that will be done is basically port tb, intake, exhaust and rtek. so stock would be good for that right? Thanks

If you are running the R-TEK 1.7 rechiped ecu, it is rechipped to run the 550cc injectors on the primarys and the 720cc injectors on the secondarys. If you run stock 550cc on the secondarys it will run lean as crap under boost. If you are running the stock chipped ECU, then running the 720cc on the secondarys will cause a bad hesitation under boost as the stock computer is trying to run the secondary injectors as 550cc. Hope that helps. Here's the link to R-TEK's website if you don't already have it. http://www.pocketlogger.com/index.php?pid=rtek7

Depends on what rtek you're looking at. With a 1.5 you should keep 550cc all around, but if you go with the 1.7 then you're going to need to keep the 720cc secondaries. (The 1.7 is designed to run 720cc or larger secondaries, so running a stock setup will cause you to run lean.)
Lastly, since you've got an 88 you need to make sure that you get injectors from another 88 when you buy some.
They should be:
High Impedance - Square Plug - Offset Notch - 550cc

checkout
http://rotaryresurrection.com/2ndgen...ctor_info.html
for more injector information

^ haha beat me to the punch

gotcha ya it is the stock ecu chipped with the 1.7 i got it off of here. so there website says 550cc primary and 720cc secondary. Thanks for the help guys

so there website its got a built in fcd does that mean i dont need one? thats what it says?

Fuel cut is removed with Rtek ECUs. And it's not the crappy fool the ECU garbage used by FCDs. The code just gets deleted.

Is it only the 88' model year that had the odd injectors? What did 89-91 come with compared to 86-87 then?

It's not that the 88 had "odd" injectors per say, it's that they are only interchangeable with other 88 injectors. 89-91 were also high impedance but instead of a square plug with an offset notch they had an oval plug with a centered notch. 86-87 were low impedance with a square plug and centered notch. The link has all the information, including how to use different impedances.

http://rotaryresurrection.com/2ndgen...ctor_info.html

Hmmmm..... well thats weird. My s5 T2 was running with square injectors.....