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Old 08-22-2010, 05:35 PM   #1
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Default afr's for different boost levels

I've been hanging around 12:1 under any amount boost but can I go a bit leaner at lower levels and still be safe?

I max out at 6 psi right now but with those afr's it feels boggy until I get to 6 and even then I feel it's too rich a mix for good power.

Would there be any benefit to leaning it up say from 1psi to 4psi? Maybe stay around 12.5:1?

Running a emb and no IC.
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Old 08-22-2010, 05:52 PM   #2
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I think 12.5:1 is very lean for boost, you should have good transition into boost as far as AFR goes, IE 13:1 at 0 vacuum, 12.5:1 at 1-3 psi, 12.0:1 at 3-5, 11.5:1 or less anything above that. I run about 11.3-5:1 from 5 psi up, since you have no IC I wouldn't run anything in the 12 range personally, but I don't like to blow **** up.

FYI I run 11.9:1 with race gas and 25+ psi.
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Old 08-22-2010, 07:03 PM   #3
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Thanks J.

IDK whats up, Maybe my lc1 is on the fritz but it sure feels like it's too rich. The plugs all have a dark black ring on the first couple threads and i'm pulling between 1 and 7 degrees timing from 1-6 psi with no audible knock. Just feels like there's more power to be had?

Perhaps i'm just in need an IC and about 4 more psi.
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Old 08-22-2010, 07:14 PM   #4
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Aim for 13.0:1 right at atmospheric (100kPa)
12.50:1 at 3 psi
12.25:1 at 5 psi
12.00:1 at 7 psi
11.50:1 at 10 psi

This is what I aim for when doing a base/street tune
dyno tuning will lead to AFRs probably a touch leaner for more power, but this should be conservative and make good power.

edit:
Just noticed your lack of IC. You should get on that asap.
I still would use my target AFRs but be very conservative with timing (the basemap youre running on is probably already pretty conservative, so I doubt you need to pull any, but Id have to see it to be sure.
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Old 08-22-2010, 07:38 PM   #5
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Not sure if you can see this, but here's what I'm working with.

boost comes on at 1.60 and hits 6 psi by 1.90-2.00.
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afr's for different boost levels-maps.jpg  
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