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A/F question

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Old 05-24-2005 | 12:13 AM
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My power is down a bit from my best but, my A/F is supposedly in the optimal band. I use HPTuners, and I think I'm lacking something, I've been tunning off of the stock o2's, but I have access to a wideband and a dyno, where should my a/f ratio be?


Last edited by 99FormulaWs6; 05-24-2005 at 12:24 AM.
Old 05-24-2005 | 01:29 AM
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12.8 is supposed to be the magic number n/a. Looks like your spot on to me, numbers look pretty strong too.
Old 05-24-2005 | 01:32 AM
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I'm happy with anywhere around 400 but I had 402RWHO before I started tuning! and on a hotter day! This is what's tripping me up. I should be a bit closer to 410 even through the 12 bolt.
Old 05-24-2005 | 07:31 AM
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Idealy, from what I've read on here, you want your AFR to follow the peak paths of your hp and tq. Many people command a 13.0 AFR except around peak tq (where 12.8 is good) and slightly after peak hp to redline (where 12.8-12.9 is good). If you can flatten out your AFR at a solid 13.0 aside from your peak tq and post peak hp, you might be able to squeeze a hair more out of it.
Old 05-24-2005 | 06:01 PM
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Your A/F seems reasonable.

I had a similar experience on the dyno the past week. I see your #'s are SAE, so that should help. I Dyno'd 4 weeks ago and pulled 412 rwhp with a 12.2 A/F - and that was after being in traffic for 2 hours. So, I went back two weeks later, similar type of day, but no traffic, so my drive was only 30 minutes and I had time to cool down. First run on the dyno was about 13 rwhp and 20 rwtq LESS than my prior best, and A/F was still the same. After tuning to 13.0 I got it back to 410 rwhp or so, but I couldn't figure out why my #'s were off so much. I figured (guessed) it was just the dyno that day.

I guess even the same dyno can vary from day to day.
Old 05-24-2005 | 08:49 PM
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Thanks guys I actually have a bit of research to do, I didn't have my tuners with me, so I didn't watch and see if I was picking up any knock, that may be an issue also. But I was also told since I was at a different dyno than my first runs that might be the issue.




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