im really sorry if this is too vague and a stupid question but just asking for a general tuning rule of thumb.

i have a b16 in my 00 Si (of couse) with toda spec b cams, p28 chipped and vafc. my A?F ratio was a 12.7:1 A/F ratio pretty much accross the board with 370 cc injectors, 14 degrees ignition timing, 5800 vtec xover, and 0, 0 cam settings:

VAFC wide throttle settings:
5500 -15%
6000 -15%
6500 -10%
7000 -10%
7500 -13%
8000 -20%
8500 -20%
9000 -20%

i advanced both cams now to: int. +1 and exh. +2
18 deg. ignition timing and 7000 vtec x-over.

if my A/F ratio was at 12.7:1 accross at 14 degrees timing and 0, 0 cam settings, approximately what you think my A/F ratio be with both cams advanced as i did with bumping the timing to 18 degrees. especially between 8000-9000 rpms? sorry if its a really retarded question, just wanted to get an estimate if anyone knows. thanks

E Lo

 

obviously by advancing the timing its giving the flame front more time to burn. so i would guess the a/f ratio wouldnt be 12.7, but a bit leaner, but not sure how much leaner??

so not sure if i should just leave the vafc alone or add 5% accross since i bumped the cam and ignition timing?

besides, i also highered my vtec xover to 7000 from 5800 so i have to lean it out a bit from 5500-7000 or just add fuel from 8000-9000. sorry again

 

12.7 measures with a wideband ?

aim for 13.3 or 13.2 ...

the vafc compensates for fuel when you move vtec crossover.

3 degree bump in timing is prolly around 0.1 to 0.2 leaner in fuel ratio relative to compression.

leaning 15% on a VAFC is too much as you are not using WOT ign timing maps from your eprom, so turn down fuel pressure and do less leaning ... or better yet PM me for a much better eprom for your ecu

greg

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CHEETAH &raquo;</TD></TR><TR><TD CLASS="quote">12.7 measures with a wideband ?

aim for 13.3 or 13.2 ...

the vafc compensates for fuel when you move vtec crossover.

3 degree bump in timing is prolly around 0.1 to 0.2 leaner in fuel ratio relative to compression.

leaning 15% on a VAFC is too much as you are not using WOT ign timing maps from your eprom, so turn down fuel pressure and do less leaning ... or better yet PM me for a much better eprom for your ecu

greg</TD></TR></TABLE>

appreciated much for the info.

yes, 12.7 on the wideband. you have pm. thanks

E Lo