im currently in the process of building a RB30DET (Forged 3.0l Bottom end, RB26 Head, GTX45, E85, Built C4). My engine builder has told me we want a 11.5:1 compression ratio because we are using E85. ill be looking to run 30+psi with this. Ive contacted Brad @ Spool Imports to see what pistons he can get his hands on that would get close to this CR. He reckons that they (CP Pistons) wont be able to fit enough Dome on the piston to achieve that. Another issue im looking at is, ill be running fairly high lift cams (between 9-11mm lift) so with such High compression im assuming ill have to fly cut the pistons which would lower the compression again surely. So what CR have people running high boost and E85 run and how did you achieve that CR (original CR of piston, work to block, HG thickness etc)?
also any hints on how to get as close as possible to my 11.5:1 CR?