I keep pulling timing....and I keep getting faster !!!
06-17-2006, 04:15 PM
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I keep pulling timing....and I keep getting faster !!! WHAT is the deal with this......
I've been trying to cure some REAL audible knock that I've been seeing - at 120º ambient with the A/C on there's a pretty good load on the engine and during rapid throttle transition it'll audibly knock
So here's my conundrum: From 1800-3600rpms and .32-.72 gms/cyl I'm 5º-7º LOWER than my previous timing table was. Now, I've pulled ALOT of timing from this table but I keep getting faster 0-60mph !!!....my best time during the winter was 5.9sec, now I'm again running 5.9sec but it's 80º warmer out and the A/C is on ?!?!, in fact I've knocked off a full second 0-60mph TODAY working on this knock issue (6.91sec this morning before tuning....5.93sec this afternoon after tuning as measured by HPTuners scanner)
Have I been inaudibly knocking THAT BAD....or does this particular head/cam combo just like less timing down low ??
(cross-posted from PT.net for better exposure)
I've been trying to cure some REAL audible knock that I've been seeing - at 120º ambient with the A/C on there's a pretty good load on the engine and during rapid throttle transition it'll audibly knock
So here's my conundrum: From 1800-3600rpms and .32-.72 gms/cyl I'm 5º-7º LOWER than my previous timing table was. Now, I've pulled ALOT of timing from this table but I keep getting faster 0-60mph !!!....my best time during the winter was 5.9sec, now I'm again running 5.9sec but it's 80º warmer out and the A/C is on ?!?!, in fact I've knocked off a full second 0-60mph TODAY working on this knock issue (6.91sec this morning before tuning....5.93sec this afternoon after tuning as measured by HPTuners scanner)
Have I been inaudibly knocking THAT BAD....or does this particular head/cam combo just like less timing down low ??
(cross-posted from PT.net for better exposure)
06-17-2006, 10:44 PM
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If you are getting a lot of knock retard, you have two things
going on. One, you are going to get spark learning toward
the low octane table. That's a pretty global penalty. Two,
you still get the knock, right? So you have KR on top of low
advance, and low advance even where you don't have KR.
Now you take out the advance excess that was a local
problem, and the learning backs off so it doesn't tax you
generally all the way down the track. Just where the KR is
still active.
Aggressive timing will help street "responsiveness" but
over-the-top just gets scaled back and double-whammied.
If you look at the delivered advance now, for CylAir and
RPM, cell by cell, this is what the truck says it likes. Now
compare that to the HO table. If the truck is giving less
than you said, try letting it have its way and it won't
fight you so much, maybe.
going on. One, you are going to get spark learning toward
the low octane table. That's a pretty global penalty. Two,
you still get the knock, right? So you have KR on top of low
advance, and low advance even where you don't have KR.
Now you take out the advance excess that was a local
problem, and the learning backs off so it doesn't tax you
generally all the way down the track. Just where the KR is
still active.
Aggressive timing will help street "responsiveness" but
over-the-top just gets scaled back and double-whammied.
If you look at the delivered advance now, for CylAir and
RPM, cell by cell, this is what the truck says it likes. Now
compare that to the HO table. If the truck is giving less
than you said, try letting it have its way and it won't
fight you so much, maybe.
