Blow-by MAF

[Xero]

how accurate is a MAF sensor put not on the turbo's intake side, but put on the compressed side, like really close to the TB? Can a Z31 MAF take it with any sort of accuracy?

THANKS!!

[huguetpj]

I am debating the same thing myself. I'm thinking that as long as the casing can take the pressure, the MAF would be even more accurate than using it at the intake side, mainly because of two things:

- Practically no delay between the reading and the actual air entering the cylinders. I' pretty sure the ECU has no delay programmed into it to take into account the difference between the reading and the time it takes the air to travel through the stock intake system (not much but there is) even less a turbo intake system.

- The MAF reading would take into account the correct air temp of the air entering the cylinders.

But when going blow-through you need to take into account air turbulence affecting the readings. For example what would happen when the BOV opens and you are using the following setup:

Intercooler - BOV - MAF - TB

Air backing out from the TB would affect the MAF, or wouldn't it?

Maybe someone with some experience could help us out here... jeje

[240marcuSX]

now, im not sure, im just thinking logically, but i dont think the MAF would respond too well to air flowing backwards through it in the opposite direction, i think that might just be asking for trouble, but i dont know. Im guessing theres a good reason they put the MAF where it is.

what about this? intercooler - MAF - BOV - TB

[Xero]

it's not flowing backwards, it's ust instead of it being pulled in, it'll be blown through,

and having IC - MAF - BOV - TB would have the same atmospheric BOV problems that it'd have if the MAF was on the intake side of the turbo,

[C-Kwik]

Hot wire MAF's theoretically should read it just the same. As long as the temperature of the hotwire is still high enough over the temperature of the air. Since the ECU measures the voltage required to keep the hotwire at a certain temp, as long as the air passing through is colder, the air will still absorb heat from the wire so it should work fine. Some have tried it and the only proplems appear to be from turbulence. Choosing a good location where air tends to be smooth will probably help keep this from being a problem. Stillen uses a blow-through set-up with the Supercharger kit for the Maxima and it appears Greddy is using a Blow-Through set-up on their turbo kit for the Z.

[:: orion ::]

I ran non-intercooled, blow-thru MAF for a month or so, and had a stumble during every shift...obviously turbulence due to MAF/BOV placement. That, and at part throttle cruising, any *tiny* accelerator blip would cause a hesitation...again, turbulence. Even if you held the pedal still, under light load, the RPMs would vary 200 or so either way randomly.

I'd think an intercooler would smooth out the flow and help this issue...but I have yet to try it. I'm happy ith my traditional setup, re-circed. BOV noise is annoying...

I don't think that (other then the atmosheric BOV option) that there's any benefit...and in my experience, it ran MUCH better as a draw-thru.

Later - Brian