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What A/F ratio do i want??

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Old Aug 10, 2003 | 11:32 PM
  #1  
ChillinEvolved's Avatar
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What A/F ratio do i want??

im gettin my car tuned soon and i was wondering what a/f ratios i should be looking to stay in to still be running safe from detonation and all that other **** i dont want happening..
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Old Aug 11, 2003 | 06:31 AM
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From: Sarasota
You have a couple choices ...

1. You can call Buschur Racing and ask them to sell u their S-AFC settings (although u may have to buy a S-AFC from them but I'm not sure -- it's worth a shot)

2. You can attempt to get a forum member to disclose his (like u just did), but you may not have much luck

3. Tune your car on the dyno with wideband o2 (this is the logical choice if at all possible)
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Old Aug 11, 2003 | 06:34 AM
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Um, on the street on 93 octane i would aim for 11:1 AFR for being safe.



-Zach
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Old Aug 11, 2003 | 06:48 AM
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i'm running 11.5
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Old Aug 11, 2003 | 06:58 AM
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From: Phoenix, AZ
Originally posted by apursell
i'm running 11.5

The 4G63s sweet spot is actually ~12:1 but that really isnt safe on the street on 93 octane.. 11.5 is probably safe, but when recommending stuff to others i go on the safe side..
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Old Aug 11, 2003 | 05:09 PM
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At what RPM on the plot are you guys reporting your single AFR value from? AFRs change across the curve and I'm not sure where the most critical axis lies. 3500 rpms at full 19 psi or 6500 at 16.9 psi, assuming stock boost map is still being used.
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Old Aug 12, 2003 | 11:32 AM
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For a somewhat rough tune, they are talking full boost everywhere. It should be stoich up to about 0 relative pressure and then taper down to 12:1 by 6~8 psi. From there, I've seen DSM's run 12:1 at full boost as a pretty safe number on 93 octane, but I would shoot for 11.5:1. You can change things a bit for spool (deaden it a bit to soften drivetrain shock), for peak torque (timing or fueling to combat a bit more knock tendency) and at high rpm (for heat loads), etc.
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Old Aug 12, 2003 | 11:42 AM
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What kind of gauge are you using to measure this Chillin - that makes all the difference in the world
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Old Aug 12, 2003 | 12:13 PM
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I'd say it would be pointless if it was not a wideband.
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Old Aug 13, 2003 | 06:57 PM
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greddy 60 mm a/f guage w/ peak hold warning etc... im using Emanage to tune... and yes i have an eo1 also so my boost is 19psi all the way up... so from reading few of the responses i am guessing i want to be 11:1 on 93 octane because it is my daily driver and i rack up quite a lot of miles .... 11:1 everyone agree? i want the MOST power while still stayin away 100% from detonation... thanks for the responses every1
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