can i turn down a pair of 1600cc secondaires with a s-afc. i have 550cc primarys and i have a turbo 2 that has a t4 upgraded turbo that i will run 10-12 psi on. will a 1600cc work good or should i go a little smaller?

 

i doubt you'll need that size....720's are good for secondaries

 

you can if you want to shoot 40 ft flames...lol!!

 

I think hes asking if he can buy these now, even though they are too much, can he tune them down, so when he upgrades later he won't have to buy new injectors, just retune

 

I think it will not work. Consider the following, first, all your adjustment points would need to be after the secondaries come on line to get enough resolution to run smoothly(IMHO). I beleive the afc will give you +/- 50%, which would get you to ~1600cc minimum(on the secondaries), this combined with -50% on your primaries would be ~2150cc.
Since we usually use 4x550cc (2200cc) injectors, if secondary tip in was based on rpm alone it could work. HOWEVER, since the secondaries also come on line at a particular throttle position(can't remember what it is) you will have far too much fuel below the rpms that would initiate the secondaries in a less than WOT situation. I think that you would need an ECU that also take throttle position and boost into account to use such large secondaries(haltec F9 maybe?).
I would think a good way to double check what I am saying would be to call a good rotary tuner like Rotary Perforance that also sells Safc's, and ask them to confirm what I am thinking.
It would take a couple pages to explain this properly(completely), It could work but I think you'll have all sorts of driveability problems.

 

from my knowledge you can't tune 1600's with an SAFC

 

Far too big-

 

a nice pair of 720cc's should do just fine like Fitness satin said.

 

720s will do fine. BUT if you tune them down the whole 50% it wouldn't be too bad I guess. Your primaries actually drop back their flow once the secondaries kick in. I have 720s in right now and am tuned to the + by about 10% just for safety until I get dyno-tuned.