Its a 3.4L I used a 3.3 block from a supercharged xterra and pistons from an infiniti q45. I saw a project pathfinder article that did this but they did it wrong... I had my friend duplicate the 3.0 vavle reliefs because he said duplicating the huge 3.3 reliefs like the the guys in that article would leave roughly .040" of solid materal under the lowest part of the relief. NOT SAFE, especially for a boosted engine. Besides, its higher compression this way.
Between the headwork and piston work I knocked the compression down from 10.3 to about 9.8 but the margin of safety with boost is much greater.Then I put a .125" radius every edge of every valve relief to elminate any chance of any hot spots. After polishing the combustion chamber and unshorouding the valves I had the heads and pistons Thermal barier coated for added safety (just incase I want more than stock boost)
I also did lots of work to the ouside of the heads since the castings seem to be good at retaining dirt and mud in the spark plug wells.
The whole thing went together with Jim Wolf Stage 1 Cams and thorley headers to complete the package.
I got 254RWHP at the dyno which if you figure drive train loss is probably about 300HP at the crank. The the boost response is near instant at any RPM as soon as I put my foot to about 1/2 throttle. It is scary fast because if your foot is into it the torque feels like full power at any RPM, I have bypass switch just to shut the boost off sometimes for safety.
Play along? Oh its all real, it just hasn't happened yet!