Couple Small N/A Mod Questions
09-17-12, 03:41 PM
#26
Driving RX7's since 1979
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ive had widebands on both stock S5's and S4's and the S5 runs really rich* and the S4 doesn't. so on an S5 car you can pick up a big gain by leaning the thing out a little, but the S4 is not over rich to start with, so the gains are really small. if anything the S4 could be a little richer, which can't be done on the SAFC's**
i don't have an S4 right now, but to use the SAFC the stock fuel system would have to deliver more fuel to start with. i would like to try a bigger fuel pump and higher fuel pressure, but that would be a $300 experiment...
*the S5's run rich, because Mazda had to warranty the cats, and so they needed to keep EGT's low(er). i've never tested an S4, but EGT's on a stock S5 stay under 720c, which is piston engine territory.
**the SAFC modifies the signal from the Air Flow Meter. the AFM is close enough to 100% open by 6000rpm on a stock car, and it'll be 100% open sooner on a modded car, because it flows more air. since the AFM is at 0 volts wide open (5v closed), the SAFC can't make it be more opener, as voltage would have to go negative.
i don't have an S4 right now, but to use the SAFC the stock fuel system would have to deliver more fuel to start with. i would like to try a bigger fuel pump and higher fuel pressure, but that would be a $300 experiment...
*the S5's run rich, because Mazda had to warranty the cats, and so they needed to keep EGT's low(er). i've never tested an S4, but EGT's on a stock S5 stay under 720c, which is piston engine territory.
**the SAFC modifies the signal from the Air Flow Meter. the AFM is close enough to 100% open by 6000rpm on a stock car, and it'll be 100% open sooner on a modded car, because it flows more air. since the AFM is at 0 volts wide open (5v closed), the SAFC can't make it be more opener, as voltage would have to go negative.
09-17-12, 04:06 PM
#27
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09-17-12, 06:24 PM
#28
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I just dont have the money for a wide band and I think that with the right A/F meter and building my own fuel maps on the SAFC or NEO that I can achieve all I need for now. I want to do a high comp turbo build next year but for now I figure I can get a used SAFC and then resell it in the future for nearly what I paid for it.
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