Originally Posted by 240M3SRT
What gap are you running? I had the colder #7 ngk plugs at a stock .039 with 12.5 afr's. I went back and lowerd them all to .025 which is a huge decrease(what MD SRT6 is running 11.2's in the 1/4 on with nitrous and 181 pully and nitrous). I ran the car again and the freaking a/f went up to 13-13.4, wtf!
Brian, do you see your a/f being greatly affected by outside temperature? As in .5-1.0 higher a/f for every 10 degrees drop in temperature.
I am running the NGK BKR7EIX-11 Iridium series plug gapped at .039. (per the Chrysler service manual)
The NGK website said that for cars running higher compression - forced induction engines running denser A/F ratio will require smaller gap - but I am not running a denser A/F ratio, and the SRT coils provide plenty of power to spark at .039 gap plus we have two plugs per cylinder. I think .039 gap is fine and works great for me. .025 seems a bit extreme. I would pull a plug to see if you are bridging between the electrodes.