twin turbo sizing for SBC 350

[purplemonster]

Hey all,
First time poster here, active on a second gen board. First background: 71 Camaro SS, 350, TH350 (soon to be TKO-600). Anyways, I picked up a set of Banks cast turbo headers for a very good deal (T4 flange/ 38mm wastegate mount). Now it comes to sizing turbos for my application. I would like to get about 600-650 rwhp at about 12 psi. For a twin setup, what would I need. By my calculations, using two TO4B 60 trim compressors would be good, but maybe I'm way off base. T04e? Even 60-1? Looking to make it a street/strip, with emphasis on street. Also I would like to go with a lower A/R for the turbines (maybe .58 or .68) for better spool. Any help would be appreciated. Thanks.

[64duece]

T04B-H3 would suit you well. Your driving style dictates which a/r suits you best.

Many of my customers like the "quick spool" of a small a/r when they're first introduced to turbocharging. It gives them the "seat of the pants" feel they're looking for. Usually they'll tend to step up as the "seat of the pants" feel wears off for increased power when they're hot.

The TKO will offer you more RPM control and some may feel the larger a/r would be better suited but, I think the smaller a/r will recover nicely after "off throttle" shifts. Again, it's your driving stlye and taste that will dictate that choice.

[purplemonster]

64Duece, thanks for the input. Yeah, seat of the pants is what I'm for right now. Still have a long way on the build. Sounds, and looks like, from some research, like I won't get in over my head with T04Bs. I see these awsome engine combos for 1000+ SBCs engines, but I know I couldn't handle those just yet. Is there any airflow vs. spool time approximation I could use? I see the .58 and .68 a/r as pretty much where I want to go. However, I also don't want to choke the engine a lower then 6000 rpm.