Quote:
Originally Posted by ss_m5
This is what’s so confusing about JB4. I thought anything above Map1 requires race fuel. This is how they explained it to me over email.
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I'll start by saying they're the experts, not me.
That said, I originally followed those same guidelines for... years I'd guess. During that time, I'd been (unintentionally) studying and had learned a lot from build and tuning threads where folks experimented in small increments and posted their results. Eventually, I started experimenting myself--in even smaller increments--and figured out what worked on what cars and on what fuel. 92 octane is what I have available so I tried map 2 with a reputable octane booster (Klotz is the brand I use). Map 2 states it requires 93 so just a small amount of octane booster got me to a point where I was comfortable to try--it worked well enough on my earlier M5s and M6s. Aside: it doesn't work well on the F90 Comp edition, map 1 is better... there's also a lesson in there.
I started logging to see what boost targets the car was requesting and things progressed from there.
Another disclaimer: I'm increasing boost targets by 0.5 at a time relative to what the car is requesting across the RPM range. Then I log for miles and miles and days on end sometimes steadily pushing the targets further. If I feel something 'off', I revert immediately and typically call it a day concluding I've hit the ceiling. Getting this stuff wrong can quite literally destroy your engine. That's a risk I'm obviously prepared to take but it's a very real risk--the evidence exists on the very same posts I mentioned earlier and on this very forum.
Map 6 isn't as cut-and-dry as map 1 or map 2 because it requires you enter boost values (I'm deliberately not saying targets here) per RPM increment plus its very behavior changes depending upon what you enter for the 1500rpm boost value--so yet more risk.
Just like the OEM, aftermarket vendors leave room for a margin of error. BMW's OEM margin is clearly gigantic; Dinan's, to me, barely pushes the envelope; the JB4 on map 1 strikes a nice balance--anywhere beyond that and you're squarely in the 'taking a risk' & 'on your own' category; the latter part being what I would expect to happen in some hypothetical nightmare situation, not what I know to be true through experience.
I'm not suggesting you follow my lead, this only explains how I 1) got to a possibly naïve point where I'm comfortable to tinker and 2) how I got the times I got today.