running rich???
12-11-2002, 01:06 AM
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running rich???
can i lose power by running too rich? or too lean??? i realize that's not good, but i'm just asking to be thourough. when i get on it, my a/f guage pegs rich. if i could be losing a bit of power, i could use the s-afc to feed it just a bit less at wot so i'm on the first or second rich led, as opposed to the richest led. anyway, i remember when my nitro r/c car ran really lean, it would have a lot more power. is the same for our (or any 4 stroke)engines? i'm not planning on doing this, though. i'm just asking.
12-11-2002, 01:20 AM
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You are not making maximum power when running rich. If you could dyno tune your s-afc, I would shoot for 13.5. Don't go too lean, it will cause damage. I wouldn't tune a s-afc unless I could get on the rollers, but, a few percent less in the top 1000 rpms probably wouldn't hurt.
12-11-2002, 03:04 AM
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Most BETA I engines use an S-AFC map that looks something like this:
Ne Points:
1000: 0%
2000: 0%
3000: -3%
4000: -5%
5000: -9%
5500: -12%
6000: -15%
6500: -17%
Don't take my word 100% for it, but after a few people with S-AFC's have come back to me with their resulting fixes, that's the general numbers they ended up with.
These cars (stock) are horribly rich in higher RPM's. Aiming for a 13.5:1 air/fuel ratio is the best, and the above-posted numbers seem to get most people pretty close.
Ne Points:
1000: 0%
2000: 0%
3000: -3%
4000: -5%
5000: -9%
5500: -12%
6000: -15%
6500: -17%
Don't take my word 100% for it, but after a few people with S-AFC's have come back to me with their resulting fixes, that's the general numbers they ended up with.
These cars (stock) are horribly rich in higher RPM's. Aiming for a 13.5:1 air/fuel ratio is the best, and the above-posted numbers seem to get most people pretty close.
12-11-2002, 04:31 AM
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None of the aftermarket A/FR gauges are accurate enough to give a specific air fuel ratio if they plug into your stock O2 sensor.
The stock 4-wire narrowband Bosch O2 sensor is accurate ONLY at 14.7:1 A/FR, at which point I believe our sensors output 0.638 VDC. Anything above or below that point is a "relative" measurement and is not accurate enough to tune against.
I have all but stopped suggesting purchase of any A/FR gauge because of this limitation. They are useful essentially only to see if your stock O2 sensors are functioning correctly and not a whole lot else. If you don't mind spending about $250, you can buy the DIY-EFI wideband pre-built setup from Australia, plus the cost of the 5-wire NGK Honda ULEV O2 sensor for another $120 or so.
That setup is very accurate in it's O2 readings, but is not cheap and just like a normal wideband should not be used *permanenetly*
The stock 4-wire narrowband Bosch O2 sensor is accurate ONLY at 14.7:1 A/FR, at which point I believe our sensors output 0.638 VDC. Anything above or below that point is a "relative" measurement and is not accurate enough to tune against.
I have all but stopped suggesting purchase of any A/FR gauge because of this limitation. They are useful essentially only to see if your stock O2 sensors are functioning correctly and not a whole lot else. If you don't mind spending about $250, you can buy the DIY-EFI wideband pre-built setup from Australia, plus the cost of the 5-wire NGK Honda ULEV O2 sensor for another $120 or so.
That setup is very accurate in it's O2 readings, but is not cheap and just like a normal wideband should not be used *permanenetly*