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Air/Fuel Ratio Oxygen Sensor Targets?

Air/Fuel Ratio Oxygen Sensor Targets?

Old January 14th, 2018, 08:05 PM
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Air/Fuel Ratio Oxygen Sensor Targets?

I just installed O2 sensors in the exhaust systems of 2 carbureted 455’s.

Both engines are mild builds, 800 cfm Qjets, with HEI, and factory duals. In big street cars, a ‘66 98 and a ‘66 Starfire.

In CA, our gas is about 10% ethanol, which I gather means I should aim at a stochiometric ratio of 14.1:1 or so instead of 14.7:1 as you would for pure gasoline. I suspect that %’age of alcohol means richer across the operating range.

I can dial in the idle to 14.1 no problem, but what are the air/fuel ratio goals I should aim at for part throttle cruise, acceleration, and WOT?

Opinions?

I understand qjets well, but I’m new to this information as inputs to tuning them.

Thanks in advance for any guidance

cf
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Old January 15th, 2018, 04:40 AM
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Originally Posted by cfair View Post
I just installed O2 sensors in the exhaust systems of 2 carbureted 455’s.

Both engines are mild builds, 800 cfm Qjets, with HEI, and factory duals. In big street cars, a ‘66 98 and a ‘66 Starfire.

In CA, our gas is about 10% ethanol, which I gather means I should aim at a stochiometric ratio of 14.1:1 or so instead of 14.7:1 as you would for pure gasoline. I suspect that %’age of alcohol means richer across the operating range.

I can dial in the idle to 14.1 no problem, but what are the air/fuel ratio goals I should aim at for part throttle cruise 14.5 or so, acceleration 12.5-12.8, and WOT Same 12.5-12.8?

Opinions?
I understand qjets well, but I’m new to this information as inputs to tuning them.
Thanks in advance for any guidance
cf
It'll also depend on the amount of camshaft in it but hope this helps.
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Old January 15th, 2018, 05:04 AM
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I can't help on this but do have a question on the subject. I have been interested in this for a while but not studied up on it yet. Do you have a recommendation on what kit to use or any information about doing this?
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Old January 15th, 2018, 05:43 AM
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I use and sell the AEM stuff, because imo it's the best stuff out there, especially for the money.
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Old January 15th, 2018, 06:17 AM
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Don't mean to steal the thread, maybe I should ask in another one... With the Jetfire models we are flying a little blind. They have a single bbl side draft carb and turbo setup. Most of them run lean with no jets or needles available. I have played with our automatic car by drilling the jet and also playing with the needle. I have it running nice but I am sure it is to rich now as I am sooting up the turbo turbine. Would it be worth the money to aid in this or is there a better way? The plug readings are all over the place with the water injected. At least they are not like I am use to seeing with ATV race engines.
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Old January 15th, 2018, 09:16 AM
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Buy the Wideband, you can use it on just about anything.
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Old January 23rd, 2018, 02:23 PM
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I use O2 wide bands from 14point7.com they are cheaper and top quality. In today's day and age I wouldn't tune a car with out one.

Ray
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Old January 23rd, 2018, 02:45 PM
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14 to 1 is good, even pushing 14.7 at idle, cruise. Moderate load, 13-1, WOT 12.5 to 12. E85 is crazy, like 8-1 but good for boost and high compression. Timing, cam, compression will play a factor but I assume you know that
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Old January 23rd, 2018, 02:47 PM
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Originally Posted by cutlassefi View Post
I use and sell the AEM stuff, because imo it's the best stuff out there, especially for the money.
I agree, for around $200 you can't beat it. Back when I was in the tuning testing biz in the early 90's through 99 a wide band afr monitor was near 15K
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Old January 24th, 2018, 04:52 PM
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Originally Posted by 74sprint View Post
I use O2 wide bands from 14point7.com they are cheaper and top quality. In today's day and age I wouldn't tune a car with out one.

Ray
Just went to that website. First thing they mention is value, not accuracy. Hmmmm
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