i turned up the boost from 11-12psi to 13-14psi. MBC grainger valve. it briefly spikes to 15psi (very briefly) then holds 14psi but closer to redline it goes down to 13.5psi or so. 100% stock fuel system. it is not high enough that it hits cut out. stock cal, no ziener diode or anything like that. stock turbo and intercooler too. i am at 4500ft elevation and it's COLD out too. 91 octane gas because that is our "premium"; the highest available here due to our elevation.
i haven't checked plugs yet but i will tomorrow morning. only real mods are full 3" mandrel bent FWDP exhaust and forged JEs FWIW. also has a K&N panel filter, Magnecor KV-85 wires, a vacuum distribution block for MAP, FPR, boost gauge (electronic Autometer) and TiAL BOV. the MBC is sourced from the nipple on the compressor outlet.
so should i be "ok" with 13-14psi on a stock fuel system or should i be using +20s and AFPR? it's only 2-3psi over stock so i figured it should be fine. a new Walbro 255 is going in very soon. i don't have WB02 yet. i cannot hear any audible detonation but i know i can have detonation without actually hearing it. pulls like crazy and seems to run very smooth. i am going to replace the plugs and then check them after "getting on it" a few times tomorrow morning.
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Joshua Mitchell
2000 Audi A6 Quattro - 2.7T/6-speed, 100% stock
1998 Buick Regal GS - S/C Series II L67/4T65-E HD, trade pending!
1991 Dodge SPiRiT R/T - TIII/A-568, 3" FWDP exhaust, MBC @14psi
1987 Shelby CSX #667 - TII/A-520, sale pending!