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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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What AFR do I Want for Daily Driver?
I've always set my CO by feel, and since I don't have to pass emissions w/ this car, I have no Idea what my settings actually are.
Recently I made my WUR adjustable, and while in for an oil change, my mech noticed I have the CO bung on my SSIs. He has a hand held AFR meter so we are going to do some test drives to see if we can maximize settings. My engine is an enlarged 80 w/ 3.2L, "approximately" 10.0 CR, and no lambda brain or onboard O2 sensor. I have my control pressure charts, the fact that JW recommends a 3.5% CO setting and I'm ready for some testing. I use the car as a "daily driver". Although it is not actually driven every day for the past 3 years, I still use it 3 days a week or so. I also use it for occasional trips. I'm not a track junkie, but, even @ the age of 60, I still enjoy some spirited off ramp type driving. Sunoco 94 is about $1.50C per liter, which is also a concern. So knowing all this, what AFRs am I trying to achieve and under what conditions?
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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07-14-2008, 06:37 AM
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Registered
Join Date: Sep 2005
Location: Yuma Az.
Posts: 282
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Take the advice of JW and set it up at about 3 - 3.5% any leaner and it will run like crap. I took Johns advice and set mine up in this range and it really runs nice now.
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07-14-2008, 09:17 AM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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So just go for 3-3.5 as recommended and not worry about whether it's 14:1 @ idle or 12:1 @ WOT?
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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07-14-2008, 01:49 PM
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Registered
Join Date: Sep 2005
Location: Yuma Az.
Posts: 282
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You want to be at 13.3 to 13.2 at idle, the more throttle you put into it, it should get richer at least mine does. Ask your wrench if you can borrow his CO meter for a day and hook it up to your car, temporarily run the wires in to the cockpit and with a bud at your side take it for a good drive. Have your bud watch the AFR ratio as you drive just to see what is happening while the car is under load. I dont think you ever will see it any leaner then the 13.3 - 13.2 range. As I said before if you get leaner then this as per John Walker, they just dont run right.
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07-14-2008, 04:59 PM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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Thanks, 76.
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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07-14-2008, 06:29 PM
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Registered
Join Date: Feb 2001
Location: Somerset, NJ USA
Posts: 269
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Isn't 14.7 ideal?
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1984 911 Euro Cabriolet 1988 928 S4 with Murf Supercharger S1 |
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07-15-2008, 08:25 PM
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