Re-scaling Maf for New Tube Size

[lanerjo]

Here is the general idea... Z32 Maf (3"tube) took the sensor and place it into a 2.5" tube as a blow through set-up... I know that I need to rescale the vq map to suit and wanted to make sure I am on the right track...

After using HPX Tool to figure out that 2.5" tube is 69% smaller than the 3" tube I take the figures in the Maf translation and change them to be 69% of the Z32 numbers... Correct?

Now should I also need to adjust the K Constant as well? I wouldn't think so being as I rescaled the Maf Voltages according to tube size (theoretically thus far).

This should put the Maf closer to my targeted HP and should also make the Maf more accurate in theory.

[Matt]

HPX scalers were used for that particular sensor, the polynomials are probably different for Z32

[lanerjo]

I only used the HPX to get an idea as to how a MAF would react when placed inside of a smaller tube basically any maf should work on the same general idea when placed into a larger or %smaller pipe... Thus I used the HPX calc to figure the are difference of a 3" tube (7.07) and a 2.5" tube (4.9) I saw that there was a ratio between the numbers inside of the hpx calc of 69% when going from a 3" to 2.5" the percent did vary by a small amount usually about .01 or less. I did not use the figures from HPX... I only found that there should be about 69% of the flow through a 2.5in pipe vs a 3"pipe.

In theory just using pi*r^2 of both a 2.5" and a 3" and comparing you will come up with 69.03%.

So I then lower each part individually from 0mV all the way up to 5040mV to 69% of its original number... This should put me in a ball park area.

[crans]

Wouldnt you just select a z32 then adjust the K const by that percentage? The curve of the maf wouldnt change just the scaling

[lanerjo]

I thought about having to change the k const... Except that take for example the hpx in a different size tube... You have to rescale the maf voltage accordingly, thus my thoughts on that are you should have to rescale the z32 as well... I know the voltage the z32 puts out stays the same except that it would try to tell the ecu it is getting more air than what is actually going to the engine... Since the standard z32 maf is calibrated to a 3" tube.... I suppose adjusting the k const might work but is it really the right way to do it?

[PL]

Z32's are not actually 3" (76mm). They're 71.5mm ID. It's the ID that counts.

Dunno why people call them 3"...

PL