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Forced Induction Turbochargers and Superchargers..Got Boost?

Stupid A/F question

Old Jul 18, 2004 | 10:55 AM
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I made some changes on my Vortech set up . I moved my air intake down to in front of the wheel well . I was told by my tuner that in may cause a vortech of air around the air filter and make it harder for the SC to bring in air . Now the question ....I put higher octane gas [96] and noticed at the track under boost My A/F was under 10 to 11.2.....would the higher octane cause this ...or may it be the SC having a hard time pulling air in ? We tuned my car at a A/F of....11.8 to 12
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Old Jul 18, 2004 | 01:00 PM
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any one.....I just dont know about the A/F with higher octane
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Old Jul 18, 2004 | 01:10 PM
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I am going to have to disagree although I have no real proof that we he is saying could not happen to some degree. The reason that I am going to disagree is that this is the same location that the AEM CAI places the filter. The AEM CAI has in some instances been shown to increase HP. The supercharger is going to suck in alot more air than the AEM ever would so if there was an air vortex I would think that the SC could overcome that. I would be more inclined to believe what ever method you used to move the filter may have introduced a restriction to the intake tract. My 2¢.
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Old Jul 18, 2004 | 01:17 PM
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From: council bluffs Ia.
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I guess the only thing I can do is put the air filter back and run the same octane gas and find out if it still is running that rich
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Old Jul 18, 2004 | 04:02 PM
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Any pics of the intake mod?
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Old Jul 18, 2004 | 04:43 PM
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Booger, the increased octane in the fuel did not cause you to run leaner. Higher octane burns slower, and if anything, it would make you run a bit richer, but even that...I have never seen when I run 100 octane race fuel.

I do notice that on certain days...or even hours...my car will run slightly leaner or richer than my target. Chalk it up to the stock ECU variability. Before you go through the trouble of removing the CAI, I would monitor the A/F over a week's time...see if it changes.
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Old Jul 18, 2004 | 05:18 PM
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Am I reading this wrong? Didn't he say he is now running richer (a lower A/F number)?
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Old Jul 18, 2004 | 05:31 PM
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Yes..I was running richer....high 10 to 11.2...I tuned the car at 11.8 to 12.2 A/F......at the track with 96 octane...I was at high 10 to11.2 while under boost
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Old Jul 18, 2004 | 05:40 PM
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One thing I've noticed is that my A/F ratios are higher on the dyno than during my "around town" WOT runs.

I've surmised that it's because the dynomometer I use (Dynapack) puts more load on the car than the typical 2nd or 3rd gear street run. It also could be due to the differences between the tailpipe reading of the dyno and the pre-cat reading of my wideband O2. But I could be wrong.

--Steve
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Old Jul 18, 2004 | 05:48 PM
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Ive never seen my gauge run any lower than 11.4 . and then just for a second . Think I will replace the filter to on the blower and see what happens . The Mustang dyno does the same thing....puts more load on than you see on the street...you can feel it
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