s4what?

What is the relationship between torque, g/sec MAF flow and sensor voltage?

I have learned, courtesy SlvrBulletS4, that the voltage maxes out at 5 v and that MAF readings have gone as high as 295-300 g/sec. Is that max reading at 5v or were the K03's maxed out?

If it's 300 g/sec @ 5 v then the relationship is 60 g/sec per volt. Is this correct? Then what is the torque to MAF flow relationship? (I'm too rushed to search for it this morning - somebody must know)

VonK :: Retired

The MAF output voltage is not a linear function of the mass air flow. It is linearized in the ECU.

mpwolf

<ul><li><a href="http://www.autoshop101.com/forms/h34.pdf">MAF Sensor (PDF File)</a></li></ul>

SlvrBullet Unloaded

I think this more of a function of the voltage ramping up more quickly in the lower gears than anything else!

VonK :: Retired

And that's done in the ECU not the MAF.

VonK :: Retired

As you know, out MAF is a "micromechanical hot film air mass meter", not hot wire.

DarinS4Turbo

g/sec is correlated to HP because it is a flow rate over time. But from that you can derive torque. There is a very *rough* guideline that 1 g/sec = 1 wheel HP, which would mean

wheel TQ = (MAF g/sec * 5252) / RPM

Now that is very rough, does not take octane, timing, and air/fuel ratios into account, so by no means is it terribly accurate.

SlvrBullet Unloaded

the extrapolation is done in the ecu but the actual output voltage is done in the MAF!

VonK :: Retired

Right. But I would say "linearization" rather than "extrapolation". :-)

Mike@VAST

a 4th order fit based on some low-flow values gave me about a 10% full-scale output error when compared to an observed max of 364.08 g/s. according to this equation, the max flow would be 401.15 at 0 Volts out.

MAF = -0.615*V^4 + 4.4545*V^3 + 14.659*V^2 - 188.43*V +401.15

Fitting data to a minimum of 0 g/s @ 5V, and ~364 g/s @ 0 V...

MAF = 16.669*V^2 - 155.44*V + 363.9

Later,
Mike