On3 70mm turbo kit on fresh build 306 sbf.
Have an 8 and an 11lb spring for wastegate.
Most likely will not be running a boost controller, just letting the spring do its job. With the hp numbers the n/a block should run, dont think will need to run much more then 11lb.
Question is, is there any benefit to running the 8lb spring for a while on the car before going to the 11lb spring? I would assume tuning would need to be done again going to the bigger spring.

 

You will have to tune at both boost levels. I will say though, just because it's a 8 psi spring doesn't mean it'll be 8 psi on your combo. I've had a 7 psi spring make 10 psi before. (Tial gate) I'd start with the 8, get your tune sorted, and then add boost if needed.

 

Thanks!! Yeah, noticed the psi variance on my present set up. The 8 may be all I need. Really only looking for bout 450-500hp(for now at least). Figuring the motor n/a should be good for 350hp then add in the 8lb, should hit round 450-500 Id think.

 

It should make closer to 540-550 if it makes 350hp na plus 8psi of boost