Maroc - SAU.COM.AU - content - 17/Aug 11:01

Engine efficiency issue?

Hi again all, i got the GTT dyno'd and the car was down on power for what i believe it should be making (very common story i know)... The power curve is good, with great Lambda readings, and drives well apart from during very low speeds i.e: carparks (seperate thread for that issue). It has all the usual parts that i reckon are pretty well matched, and in some cases, overkill for my needs (i'm ok with that). 2.5L Neo with supporting mods, manual trans kelford drop-ins, Performance springs, Ferrea S/S exhaust valves Hypergear ATR45SS-2 (gtx3582 compare) 6boost, 3.5" exhaust, 60mm plumbback gate Plazma pro-series cooler, tophalf and 66mm TB. Haltech elite 2k on E85 , Ross triggers, R35 coils - Power peaked at 530rwhp on hub dyno at 8k (25psi boost). The tuner commented on how the engine wouldn't respond with more boost, as if there is a restriction somewhere. Tapped out at that power level.... Couple ideas for what would be choking up the engine would be ; - Plumbback causing backpressure, got some advice to convert to screamer - Valvespring tension incorrect, causing float at 25psi and up. I didn't test and shim the springs, i just installed them with a shim under each one. Perhaps the Ferrea locks are a different height? Torque curve is smooth all the way up, no erratic spikes on the curve, so not sure if its actually floating.. I reckon this setup should make over 600rwhp at peak with this setup.. Thoughts on either option, or another potential issue?