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#1 |
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Have added a single O2 sensor to a racepak sportmans unit.
It is mounted on the collector just after merge. Running a BBC on C12. I know location is not the prime Spot. I am only taking values above 6000 for comparison since The sensor is in the collector. The "lowest" reading I very see is 13.8 and that is only in High gear at higher rpm What values should I see and does the motor load effect The AF value. The 13.8 is lean correct? But plugs look Ok. Haven't tried bigger jets let but will soon now tracks are Opening up Thanks David |
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13.8 is rich by around one point. Perfecto is 14.7.
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Dale Shearon 68 Mustang 6394 |
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1989 Camaro Iroc-Z I/SA B&B Auto Machine Shop. |
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14.7:1 is only perfect for a street car on pump gas. It is a compromise that a few different factors meet @ to be stoichometric. (for emissions to make the catalytic converter work its best) USUALLY, when you mash the gas you want the AFR to drop to around 12:1 - 13:1. Different manufacturers and different cyl head designs, compression ratio's and probably several other factors determine where an engine makes its best power @.
18:1 works for mileage but sucks for power, if you can keep the fire lit. ![]() https://x-engineer.org/wp-content/up...io-300x296.jpg
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Dave Noll, E/FS ,?/SA 6526 Last edited by Dave Noll; 06-23-2020 at 07:28 PM. |
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#5 | |
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https://x-engineer.org/automotive-en...e-performance/
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Dale Shearon 68 Mustang 6394 |
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If you want to read more, try some of David Vizard's stuff.
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Dave Noll, E/FS ,?/SA 6526 |
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Dave Noll, E/FS ,?/SA 6526 |
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#9 |
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My plots look backward compare to what everybody
Is explaining The first plot was in 3500' air and the second Was 300' air. No changes in the car at all. The graph index for A/F is 10 to 15 at the top of the graph The first plot has a 12.8 reading at top of 1-2 gear change The second plot has a reading 12.1 at 1-2 gear change Plots show lean in the worst air of the two. Am I looking at correctly. [15 lean. 10 rich]. ? This is why I am confused by readings Couldn't upload a higer resolution pictures Thanks David Last edited by Willyracer; 06-26-2020 at 10:59 PM. |
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When you get tired of reading what all the experts say... Go to the track and tune your engine where it is happy.
Best ET and MPH in the conditions available. Then hook up your gauge and let it tell you what the A/F ratio is. Your dealing with arbitrary numbers and your engine combination may not be happy with them. I loved it when I was dyno testing and had customers tell me the EGT and AF had to be certain numbers to make power. Their engines usually told them something different. When making power most engines accelerate when slightly rich at peak Tq and run up toward lean at peak HP. In the car I like slightly rich at the gear change to produce Tq and pull off the gear.
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Adger Smith (Former SS) Last edited by Adger Smith; 06-30-2020 at 05:35 PM. Reason: sp add |
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