how much boost can you tune for on stock 420a injectors?
i have 450's but dont know if i should drop them in yet.

i want to tune for 8-9 psi , what should i do?

i have a wideband and the safc2 , fuel regulator (rising rate)

 

MY friend Sean has been running 10lbs. on his stock injectors for probably a year and a half maybe two years now..

 

Well if those are 450cc injectors from a 1g dsm you will need resistors or resistor pack. I have the resistor pack if you need it. If they are 450cc injectors from a 1g dsm you would need to change the o-rings to the 420 injector o-rings for them to fit in the fuel rail. Might as well tune the car once you put in the injectors, I would also suggest a sfmu if you don't have one because fmu 12:1 is if you'll be running stock injectors. No sense in tuning if your not done with you setup and you might drop in bigger injectors soon. You can tune now but heh fuel cut will haunt you and then you have to tune again once you swap your injectors. If you know how to tune then it doesn't matter if you tune now or after the injector install but if you don't then why pay twice?

 

Or if he has a FMU he can simply get a 8:1 disk from vortech to run the bigger injectors

 

i have allready put new o rings on the450 blue top injectors ( 420a o rings). i also have the resistor pack. i have a begi riseing rate fuel regulator with the fuel pressure gauge.
what else do i need? but mitsubishimike said i could do 10 psi with stock injectors so i think i will hold off on the bluetops for a bit. maybe when the 2.4 block is finished next month.

 

9-10 boost psi on stock injectors will work for a short while. However with the stock 420A fuel pressure you should be at 50-55psi with no boost. When you boost on stock injectors you will see 100+ FP to compensate. Now on stock 235cc injectors, 100psi is a lot of pressure. Some have good luck with them, others crap out. It all depends on how good the injectors are and if such small injectors can take the added abuse. Keep in mind everyone that not all fuel mods for the 4G63 will work with the 420A (ie resistor pack) It all depends on the car. The most "standard" mechanical tuning for a setup like this (meaning most 2gnt'ers are running a stage 2 setup) would be to use 30lb/330cc injectors and with an SFMU lower your idle fuel pressure to 22psi. When you hit boost you would be right at 45-55 psi on fuel pressure. This setup has worked out a lot for people due to the ECU thinking while the car is under boost, it is still reading the base fuel pressure of 50-55 and not correcting by having you run ridiculously rich or going into fuel cut due to running lean.

 

thanx hunter shoulf of asked you 1st
thanx every one else as well