ash.zero

can someone explain the term "boost comp"? i'm using ems and i've been reading up on it, but can't seem to find a good source of info on this topic. i've checked ems forum as well, but that forum moves as slow as snail.

also, if you're building ignition table, i know that you're supposed to retard / pull timing per increase in boost, what's a general rule of thumb here? if someone can explain this, it'd be great. (more detail, better it'd be )

thanks.

Boltz

Not really sure about your question on the EMS but .5 degree retard is a pretty general retard per pound of boost. .75 is very conservative

ash.zero

so if the ignition values are:

psi___|___rpm___|___ign
-0.03_|___5000__|___35.7
-0.03_|___5500__|___35.7
-0.03_|___6000__|___36.4
-0.03_|___6500__|___38.5
-0.03_|___7000__|___38.5
1.53_|___5000__|___34.3
1.53_|___5500__|___34.3
1.53_|___6000__|___35.0
1.53_|___6500__|___37.5
1.53_|___7000__|___37.5

this what aem basemap came with. as the psi increases (more boost) the ign value be smaller by .5 per 1 psi of boost? thank you.

ash.zero

also, i found this link: http://www.pgmfi.org/twiki/bin...Ratio


"I'll be aiming for:

13.5 AFR while NA. 28 degrees timing at boost/NA transition peak power production. Timing retarded by 1 deg / 1000 RPM on top side of RPM band after peak power production.

12.5 AFR from 0psi to 3psi. retard 0.25 degrees cumulative by 3psi (i.e. 0.08 degrees/psi)

12.25 AFR from 3psi to 5psi. retard 0.75 degrees cumulative by 5psi (i.e. 0.25 degrees/psi)

12.0 AFR from 5psi to 7psi. retard timing 1.75 degrees cumulative by 7psi (0.5 degrees/psi)

11.5 AFR from 7psi to 10psi. retard timing 5 degrees cumulative by 10psi (0.75 degrees/psi)

Timing ends up at 23 degrees @ 10psi ... little on the high side but not much. The gradual increase of retard is called a "step-retard." The step retard is designed to retard the timing when it is needed (high boost) and leave you with as much advance as possible when you don't to spool the turbo and get overall better performance. (low boost) BE CAREFUL. The key to a good step retard is to figure out where you want your FINAL timing to be, and work backwards from there. "

this guy seem to pull not as much timing as the basemap i have. any thoughts? thanks.

ash.zero

where did all the tuners go??

ash.zero

what happened to this forum?

SOHC_MShue

yes you want to do a step retard. Pulling .5 per pound of boost is gonna make your car sluggish in low boost. You barely need to pull any timing out under 5 or 6psi.

g0ldywang

v

ash.zero

good deal. finally some clarification! thanks.