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Message: <blockquote data-quote="garrittpwl" data-source="post: 1569771" data-attributes="member: 21560">Okay so a little about turbos, a little about valve spring seat pressure, a little about displacement and a little about my issues.Too Long Not Gonna Read Preface; I'm trying to find out if I'm floating the valves or if my turbo is still too small....Start with the details, turbo built 5.4, e85, +1mm valves etc etc.I've got a second hand turbo kit with a 70/65 .68 AR turbo that I ran last year, car made 573/610 at 5200rpms, but the graph looks like an ecoboost after 5200 rpms. Didn't matter if 7psi or 14psi, 5200 was the limit on power, although I could continue to rev the engine to 6500.picture of said graph at the bottom of this post. (note the 469 pull was 7psi and the 573 was 14psi. They both max hp at 5200 which corresponds with where the MAF stops climbing).Fast forward to 2025; I installed a gen1 VSR 78/75 .96AR turbo to see if I could get some more RPMS out of it (got it stupid cheap). Haven't had a dyno log on it but per the MAF and datalog on some mexico pulls, the MAF isn't reading any more counts after about 55/5600rpm, regardless of boost level.I don't think it's valve float (unfortunately I'm not sure the exact spring thats in it as they came second hand as well). I was told they're comp beehives but idk. machine shop seemed to think the seat pressure was around 100lbs back when I built it, and honestly I've never thought about it again until now. I know they're not factory springs as I'm running .550 lift cams without binding. Now I also know the math behind calculating valve surface area and the PSI against it. But my thought is that if it truly was valve float, the more I turn up the boost, the less and less RPM the car would turn before the issue arises.My thought is that even with the upgrade on the turbo, I'm still not running a big enough turbine/AR.What are yall's thoughts?[ATTACH=full]43133[/ATTACH]</blockquote>