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Discussion Starter · #1 ·
I am taking my Bullitt to the dyno for the first time tomorrow. Since I am currently running only a boxed tune in my SCT Xcal3, I am not sure if a custom tune would be much better. Is the air fuel ratio montiored when a pull is done?

Is it simple to adjust the fuel between pulls if I go rich or lean during the pull? I am getting 2 pulls for $40 at a local Mustang event, and I'd like to maximize my benefit if anyone can give me any advice.

THANKS!
 

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Depends on what they include for that price. The correct A/F readings depend on what condition the shop keeps their A/F monitor's O2 sensor in.
A good N/A tune should be in the 12.8 to 13.0 range,at WOT. You can trim to that level by adding or subtracting percentage of fuel,and or spark timing,using your SCT programmer.
I do my testing,on a secluded back road, in 3rd gear WOT,up to 5200 RPM.
However, while at the strip,my readings came out about a tenth of a point leaner,while in the top end of 4th gear. This could be due to the greater air flow going into the JLT CAI setup at over 100 MPH. I was tuned in at 12.7 to 12.8 in the 3rd gear test.
 

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Discussion Starter · #3 · (Edited)
3934 pulled the following numbers today on the DYNOJET:
263rwhp & 304rwtq UNCORRECTED(How does that relate to other results?)
The air fuel ratio was a very consistent 13.95:1.

Is this too high? Should I try to tweak that down a little or just leave it alone. How much do I need to change it? I have the SCT Xcal3, but don't plan to take it back for any more dyno pulls, so I won't know what my air fuel ratio is after adjustment if I do so.

What do you think?

BTW, I am very content with the dyno results based on the mods I have.
 

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13.95 A/F is on the lean side,for WOT. I would bump up the fuel 2% RICHER. Look into getting a A/F monitor,like the Innovate LM-1 unit,or better. That is what I use to tune both carbed and EFI setups. 12.7 thru 13.0 is a good safe range to shoot for.
 
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