88 TII -
running stock turbo, racing beat turbo-back exhaust, ported wastegate, street port, removed emissions, walbro 255, k&n cone filter, and SAFC2, boosting to 10psi. Would 680cc seccondaries be enough or should i go for the 720s?
thanks.

 

Should be fine,unless its a big port job.

MY old S4 setup used a S4 block,S5 stock turbo,550's and 680's,FD fuel pump and stock TMIC,maxxing out 14psi all day long,no fuel controller.I used to take it to the track every week (mid 13's) and daily drive it.
Never once pinged or complained,although at the track I had to ice the crappy little TMIC between runs, in the summer.....at night it screamed.

Currently running 550's and 800's on my streetport S5 setup with TO4B hybrid and FMIC.Still hitting 14psi and loving it, after over 5 years....

 

ya 680 would work but because you have an safc2 you could put 720s and you would be fine also....

 

Ok thanks guys.

 

I'd run 720's to be safe. you're going to be pushing that setup pretty hard

 

Here is some fact for 680 cc's GSL-SE injectors,this was posted by "renns" in the fuel injection subforum .

"FSM says GSL-SE injectors flow 173 cc/15 seconds at 39.7 psi, or 692 cc/min. Multiply this flow by sqrt(43.5/39.7) to get nominal flow at standard 43.5 psi fuel pressure = 724 cc/min"

Enough people have flow tested those to confirm this.Get's tiring reading about the 680cc GSL-SE vrs/ 720cc injector debate.OK?

 

just have them cleaned out and balanced.

 

I'm running stock 550s all the way around with essentially the same setup ('cept for a microtech) and my AFRs are all good...