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Dual Mass Air Flow

Reason

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the stock mass air flow meter poses a significant restriction in the air flow as one approaches and exceeds 500rwhp

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the restriction is apparent from these pics

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parallel MAF's would allow more than enough intake air

Physical Design

bulletintake -> Y pipe -> 2 MAF's in parallel -> Y pipe -> turbo
bulletuse the A'PEXi S-AFC or Greddy e-Manage to combine air readings (and compensate for larger than stock (550cc) injector size if desired)  (Note the e-Manage does a superior injector size compensation to the S-AFC)
bullet 2maf.jpg (46487 bytes) pic of design (by Mohd)
bullet dual_maf.JPG (94053 bytes) pic of 90 percent complete dual maf setup (by Phil P.)

Wiring

bulletHarness M1 (to MAF)
Wire number 93.5 - 95 Colors 96-98 Colors Usage
1 black w/ red stripe black w/ red stripe +B (power; 9 - 14V)
2 yellow w/ red stripe yellow w/ red stripe VG (O2)
3 pink w/ blue stripe green w/ black stripe THA (temp)
4 brown w/ black stripe white w/ black stripe E2
5 brown brown E2G (ground)
bullettap into power and ground and connect them to the 2nd MAF
bulletwire from 2nd MAF O2 value goes back to S-AFC blue wire (see Nissan 300ZX instructions)

S-AFC settings

bulletset to combine O2 sensor signals from each MAF by adding
bulletif installing 720cc injectors set the low and high throttle baseline settings to -24 percent
bulletcompensation percentage = ((1 / (new injector size / stock injector size)) - 1) * 100
bullet720cc injectors will flow 30.9 percent more fuel at the same duty cycle
bulletif one has 1.309 times the fuel then 1.309 * .764 = 1 (the correct amount of fuel), i.e. -23.6 ~= -24 percent
bulletif installing 850cc injectors average the 2 MAFs (instead of adding) and set the low and high throttle baseline settings to +29 percent
bulletcompensation percentage
bullet850cc injectors will flow 54.5 percent more fuel at the same duty cycle
bulletif one has 1.545 times the fuel but the s-afc is putting out the average of the MAF's then .5 * 1.545 * 1.294 = 1 (the correct amount of fuel), i.e. +29.4 ~= 29 percent

last modified on Saturday, January 19, 2008

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