Changing Afm Internals

[sinistaGTR]

This is just a theoretical.

I'm upgrading the gtr ATM and unsatisfied witht the cost of nismo afm, I'm looking at going rb25 or z32 afm. Just wondering if it's possible to swap the internals of these into the rb26 bodies. As I said it's just a theoretical idea, but one I have been thinking about ATM. The idea of keeping to stock airbox without modifying to fit bigger afm is fantastic but not keen on spending 1k on afms.

[R31Nismoid]

The AFM calibration needs to change if you put a Z32 sensor into a GTR housing. It won't read the same if you do this as the piping is smaller and the AFM calibration does not understand this.

This is why a Z32 & Nismo AFM are not identical, they actually read differently.

It works the other way also by putting a stock AFM into larger piping, it will max out later using the same sensor

I'm still confused though as to why you keep saying they are too expensive/$1000???

Z32 Just Jap - $700

Nismo AFM - Greenline - $800 (+$15 delivery)

A lot of stuffing around to save $100

[sinistaGTR]

Thanks for the info

[Room42]

The AFM calibration needs to change if you put a Z32 sensor into a GTR housing. It won't read the same if you do this as the piping is smaller and the AFM calibration does not understand this.

It works the other way also by putting a stock AFM into larger piping, it will max out later using the same sensor

So changing the afm pronger into a different size pipe sounds like an easy way to scale your afm.

[GTSBoy]

So changing the afm pronger into a different size pipe sounds like an easy way to scale your afm.

Yeah, except you have to come up with your own trustable flow curve to put into the ECU. With Nistune you can put in an arbitrary curve, I don't know if you can do it with a PFC. Either way, making the curve up correctly is not something you can do just working theoretically. You should do an actual bench test to work out how much it flows in total, and what voltage it puts out for each fraction of total flow.

[Room42]

Yeah, except you have to come up with your own trustable flow curve to put into the ECU. With Nistune you can put in an arbitrary curve, I don't know if you can do it with a PFC. Either way, making the curve up correctly is not something you can do just working theoretically. You should do an actual bench test to work out how much it flows in total, and what voltage it puts out for each fraction of total flow.

I don't know a lot about it for the pfc as I haven't researched it yet but I do know that using the datalogit there are 32 points at which you can adjust the curve. There are 20 load points in 400 rpm increments that have a load value which is adjustable. There is a number that corresponds with each of the 32 voltage points that is adjustable to set the curve values. I don't think it is the load value tho because the numbers in there don't match up. I have no idea what this number is. Does someone on here know?

[R31Nismoid]

Don't forget in a PFC you can just "select" the AFM, and it already knows the calibration out of the box.

Doing it manually would cost time to test & tune etc.

Whilst it is cheaper to do it to a stock AFM than purchase a Z32 AFM for instance in pure cost - end of the day it still costs you money (tuning/testing) & a lot more in time and effort. I reckon it would be lucky to be $100 difference @ the end.

You also have to remember you still have an OLD AFM element/sender. Doing a transplant could just be enough kill it so all stuffing around to find the AFM is playing up or gives you grief whilst trying to tune?

Not fun at all

[Beer Baron]

yeah all the way you can try and save a few bucks are a bit of a false economy. I think my last set of nismo afms was around $750 brand new (in fact I still have a spare set I should flog). for that money they are well worth it. they fit whatever piping/filters/airbox you have now and they are brand spanking new.