Searching and learning and trying to figure out maps but you gotta admit it's probably a little more difficult finding info for a big displacement engine that only turns a max of 2800-3000 Rpm compared to a 2L. I played with the not2fast calculator and the dot looked to me like it was where it should be with a T61 map. CFM required is about 600 or 40 Lbs/min at 3000 rpm with 8 psi boost but it would be nice to be getting into boost by 1000-1200 rpm. Just hint if i'm on the right track! Thanks

 

PICKED UP A HOLSET HX38g for this build, I'm hoping it spools quick enough with the 520 cubes.. HX35 compressor with a HX40 turbine and T4 split housing. It also has a water cooled center section that I don't need but whatever. Not a well known turbo!

 

Probably in the right ballpark, especially as the engine displacement and RPM range is pretty similar to a diesel.