Stage II...how much boost is safe?

Whiteshadow · 10-03-2003, 11:37 PM

I have a Stage II Star Kit on the 420A, the motor has JE Pistons Crower Rods, Valve springs and retainers off of a GSX...can this motor handle 20psi? right now the wastegate allows me to go to 10..how much boost is safe? Im not sure about the injectors but they were rebuilt or what not when the turbo went on...Thanks for any help

SnoopySLR · 10-04-2003, 11:02 AM

Can you use valve springs and retainers from the 4g63 on the 420a? I didn't know you could do that.

gofaster87 · 10-05-2003, 10:58 AM

To push 20psi, you need to work on your fuel and ignition system. There are alot of threads on this subject so you should find some good answers.

Whiteshadow · 10-05-2003, 12:53 PM

Everything i have searched just talks about star vs hahn or else i wouldnt have posted...when you say ignition do you mean something like MSD or along those lines, as for fuel i think bigger injectors is the only thing left to add...ill keep it at 10psi for now

slodsm · 10-05-2003, 01:10 PM

much larger injectors for 20 psi, I have 440's on my 420 A and that is for 16 psi. I imagine you would need somewhere along the lines of 550+ to keep them on a low duty cycle. Also you will need some form of engine management or a piggy back and a good amount of dyno time.

Whiteshadow · 10-05-2003, 01:35 PM

thanks man...thats what i needed to know...i still need to get an exhaust on this thing:o 2.5 or 3

Kirby · 10-06-2003, 02:00 PM

If you want to run 20psi get the 3 inch. Something is not right here though, is this the 420a or is this a 94 n/t with a 4g63. No parts from the 4g63 work in the 420a so that can't be right. Did you buy this thing already built and with the kit? You need to findout from the owner what is on your car and I mean every detail, then we can guide you further. but to be honest with you if everything is set up right 20 psi on that thing would be no problem.

Whiteshadow · 10-06-2003, 05:13 PM

to clear things up it is a 420a w/turbo....i do drive a 94 with a 1.8(soon to be 4g63T) anways the 420A is my friends car and hes just a lazy ass so he told me to post this up for him... as said before though everything is built up bottom and top....so to my knowledge as of now, he's gonna need bigger injectors, 3 inch exh, AFC or something along those lines, and maybe some ignition...anything else im forgetting let me know...im sorry about the confusion kirby