Target Air Fuel ratio for NA Cobra 4v? - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 9 Old 05-07-2002, 08:11 AM Thread Starter
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Target Air Fuel ratio for NA Cobra 4v?

Just used a Bailey AFM-1 on my 99 Cobra. It is lean at 14.0:1 Air fuel ratio at wide open throttle in 2nd and 3rd gears throughout most of the rpm range. Richest I saw was 13.9 at 6200 about. My understanding is that the target should be 12.7-13.0 normally aspirated. What do the tuners normally shoot for on normally aspirated street engines when burning chips?

I don't have a data logger set up yet to take the output from the wide band and an rpm signal and record it real time on a lap top. But I'm working on it.

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post #2 of 9 Old 05-07-2002, 10:40 AM
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Dont know if this helps Joe but I remember my A/F Ratio being 13.2 ish NA and 11.7 on spray. I dont think this is a 2V,4V or Mod Motor specific question. I would post this question in Windsor Forum and I bet you get the answer you need.



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post #3 of 9 Old 05-07-2002, 12:38 PM
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Joe,

Just lurking and reading, Ive seen that most tuners richen the A/F up one step from like 13.x to 12.x.

I am wondering if gutting the stock MAF would accomplish this as well? I want to buy a spare and carve it up, but I have not found one as yet.

Also, Joe, what do you think of the The RACE Systems SnEEC-IV Real-Time Data Logger?


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post #4 of 9 Old 05-07-2002, 02:07 PM
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Joe, That's really lean. I'm surprised it didn't dentonate. I have an a/f of 13.1 all the way to 6200 then went to 12.5. This was done w/ no chip and just an adj fpr. IMO anything over 13.5 is getting risky. Gotta take into consideration of hot days and bad batches of gas ya know. -Mark

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post #5 of 9 Old 05-07-2002, 03:35 PM
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Joe,

I can confirm what others are saying. 12.5:1 to 13.5:1, depending on the engine. Most seem to do best in the upper 12s.

Chris

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post #6 of 9 Old 05-07-2002, 04:58 PM
 
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Jason Meiers and other N/A 4V cars have made the best power at 13.1 A/F ratio...That seems to be the optimal level for the best power on an N/A car...


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post #7 of 9 Old 05-07-2002, 09:23 PM
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You want an A/F ratio of 12.8 - 13.0 for a N/A 4V

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post #8 of 9 Old 05-07-2002, 11:29 PM Thread Starter
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Thanks guys. I will shoot for the 12.8-13.0 range.
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post #9 of 9 Old 05-08-2002, 12:43 AM
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Yeah just to back up what everyone else is saying, Jimmy LaRocca tuned mine at a A/F ratio of 12.5:1. He tried a 13.2:1 and didn't get any more power out of it than the 12.5:1, so he put it back down to keep it from possibly detonating on bad gas. This a/f ratio also gives me more room to play with my timing adjuster.

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