ok... first there is not enough octane for 27psi (95 octane)..
Second (after running atleast 104 octane) you need to be pulling atleast -25% on the safc from 3500 to redline for 27psi.. remember this is a 3 bar map. The stock pcm maxs out the pulse width at 89% at 18psi. It pulls lots of timing to try and reduce boost over 18 psi. You will have the same fuel being put into the engine at -10/-15/-20 and -25% at 27psi.. With the rising rate regulator set at 50psi vac line off you will have 70 psi at 20psi boost and 77psi at 27psi boost.
Rules:
Pcm must not see more than 18psi.. set the boost to 18 psi get a map input voltage reading on the sensor screen of the safc. Then turn the boost up and the % down so that the safc map output is never above that original 18 psi number.
Never run more than 22-23psi on 93 octane on a stock pcm .. you can but you will see spark retard due to knock.. whenever you see dips in the power band it is usally due to knock induced spark retard. when you see rapid dips and spikes thats detonation.
Always run enough octane plus 2 points..
buy a scan tool to montior knock.
Nemo
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