Ok...

So I'm not understanding so well, is the point of a getting a bigger MAF is to increase the range of air it can detect (example: getting a z32 MAF to operate on 1-8v versus a stock MAF operating on 1-5v)

Or is it to reduce the output of the MAF based on the volume of air? (example: 50CFM of air intake sending 2.0v on a stock MAF, but 1.5v on a Z32 MAF)

please note, all numbers are strictly just there as numbers, I don't assume them to be accurate, neither should you.

Now, depending on the answer, for the higher operating range, why doesn't the ECU freak out at 5v just like it would with a stock MAF -- and if the answer is for reduced voltage, wouldn't that result in the ECU sending the wrong injector pulses to the ECU thinking there is less air?

I'm asking these question based on someone saying that with an upgraded MAF, you still have +/- 50% adjustability with an S-AFC, so to me that assumes there is no compensation required for the bigger MAF itself.

Sorry for the long post, but I like to be detailed, I've found it gets you better answers. Thanks.

Both MAFs still read between 0-5 V

Your stock ECU will flip out, because 3 V from a KA MAF is different then 3V from a Z32 MAF, at 3V there is more air beeing read from the Z32 MAF, but your ECU doesn’t know that, it doesn’t have the scale map, the MAF does

(using arbitrary numbers)

This is where a hacked MAF comes in, you increase the surface area of the wire so that at a certain air flow, the Z32 maf wants to read 3 volts, but because of the larger wire it reads 4, the ECU thinks its 4 volts, that is the corrected reading. you don’t want your ecu reading 3 volts, because with its scale 3 volts is not allot of air, but in reality more air is passing threw

Maybe I got this backwards, someone correct me…or word it better

No and no.

Toki is kinda right. When you change the stock MAF for a Z32 MAF at the same amount of air the stock MAF would output more voltage than the Z32 MAF. Neither of them will output more then 5V, but the stock MAF does this at about 250HPs worth of air. The Z32 MAF does this at 500HPs worth of air. Unfortunately the MAF response curves are not linear so the ECU needs the correct VQ map to linearize them, and the VQ maps are not linear to each other. If you connect a Z32 MAF to the stock ECU it will not work.

This is where the SAFC comes in. Since the SAFC has both IN and OUT settings for MAF sensors you can say that you have a Z32 IN and a KA out. So, using what I guess to be the equivalent of VQ maps the SAFC will adjust the OUT signal to compensate for the different MAF. You still can have a +-50% adjustability from this setting since you have not touched the high/low maps for the SAFC, you have just told it to use a different MAF.

Now, checkered does have it backward. The hacked MAF only works if you use bigger injectors. Smaller injectors is also theoretically possible but of no real use. When you increase the cross sectional area of the MAF the hot wire will read less air going in, since more can bypass it on the bigger cross sectional area. Now, if you have stock injectors you would be leaning the AF mixture. If you use 370cc injectors, which are 37% bigger than stock or stock being 27% smaller, you would have pig rich AF mixtures. If you use them both, 370cc injectors with a hacked MAF with a 27% bigger cross sectional area then they even each other out.

Hope I explained myself

i don't see why you couldn't use a simple yet precise amplifier to double the output voltage from the 300zx MAF. (some additional circuitry may be needed to keep the signal voltage from exceeding 5 volts.)

you would still have a ~250hp maximum but you could run a larger MAF: less restriction in the intake.

Putting all that work in just to get a tiny bit more airflow isnt worth it, but a new maf and injectors put together with a reflashed ecu or management system is a very important upgrade.

Turnman261 wrote:i don't see why you couldn't use a simple yet precise amplifier to double the output voltage from the 300zx MAF...

Because it's not a linear realtionship...

It's a voltage CURVE...so where 3000rpm at no load may give you 2v output with a stock MAF, it may be 1.5v with the Z32 MAF...

And 4500rpm under load may be 4v with a stock MAF, it may be 2.3v with a Z32 MAF...

And WOT at 9psi may be 5.11v from the stock MAF, maybe it's 3v from the Z32 MAF...

Etc, etc...

- Brian