#24072, "RE: Why retard ignition while boosting?" In response to Reply # 0
Retarding the timing will preven spark knock, but it will also make you slower. If you want to go faster you want to advance timing, but be careful too much advance you will get spark knock.
#24073, "RE: Why retard ignition while boosting?" In response to Reply # 1
Our engine advances timing quite a bit. I've heard anywhere from 20-45 degrees. That does result in quicker air/fuel combustion, but when you are boosting, there's a lot more air going in to the combustion chambers (especially at higher boost, 15 or more psi). When the ecu "sees" a greater MAP, it's going to advance timing even more, but that increases the possibility of knock (detonation--which is when the combustion of air/fuel occurs too soon--before TDC). Retarding timing will delay or pull back timing, in % of degrees, to minimize or prevent detonation. And, of course, when you "pull back" timing, you are also loosing a bit of acceleration speed. It's better be safe than sorry. With my Crane Retard module set at the first mark, I could feel that slight "delay" in acceleration. I haven't data logged my car yet, so I don't have any real numbers to show you yet.
___________ Kon C
"Sometimes, a man has to do what a man has to do."
#24075, "RE: Why retard ignition while boosting?" In response to Reply # 3
I've seen it on my data logger. I have about 21deg advance at 15psi and WOT. I will be data logging on wednesday at the track for 20psi and race gas. It will probably need some retarding at 20psi
#24077, "RE: Why retard ignition while boosting?" In response to Reply # 5
Yep, I remember having read on this forum by a few people who have datalogged their cars that, that's those are just some numbers they've seen. I believe it will vary from car to car, though.
#24079, "RE: Why retard ignition while boosting?" In response to Reply # 7
Stage IV is awesome when I punch it. I could break loose in 2nd or 3rd gear on dry pavement! I'm always afraid my axle will break or something. I don't know; I get this inner grin whenever I'm on the road, as if I'm not easily intimidated by any domestic muscle car anymore.
#24081, "RE: Why retard ignition while boosting?" In response to Reply # 9
Nothing on the road scares me except me. There are, very certainly, faster cars out there. I'm the only one that scares me
You want to retard timng while boosting because this ECU is tuned to make good power NA - it increases advance at a rate that will cause knock to a high HP, FI car. When this ECU gets knock, it pulls timing WAY back - around 14* at WOT. if you take a few degrees out before it reaches that knock-causing peak, or take a degree or two up top where you might be knocking just from the high boost and advance, you'll end up making more power overfall by being able to maintain a steady smooth timing advance over your whole powerband without knock induced dropouts in your timing curve.
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