legacycentral bbs

I was thinking about how I could find out the transfer function of this MAF I got and got an idea. Plumb the new MAF in before the intake system of my car and make shure it has power. With the car running, I could read/graph the outputs of both, and use prior knowledge of the stock MAF's curve to extrapolate one for the larger MAF. Does this make any sense?

I'm not having much luck looking for the transfer function online.

That should work decently... the extrapolation is the only part that might be stressful. But most MAF sensors do have (nearly) quadratic transfer functions.

I know that MAF sensors also multiply errors. So if I didn't get even flow through it, the curve could be incorrect. Hmmm. I just wish there was an easy way to find the transfer function for a large MAF.

I've worked with wire MAF sensors in a few of my labs but we haven't really done transfer functions for them. I would think though that different MAF sensors will have a slightly different transfer function, especially hot wires vs. flat film vs. conical film vs. element material vs. etc, and that's what makes it so hard to find anything specific on the net. Depending on what software you have available, once you get your data you can do a good regression and get resonable extrapolations.

Yes, Lee, you're right that every MAF sensor has a different transfer function. And that function does depend on the pattern of airflow through the sensor. That's part of the reason that modifying the intake of a MAF-equipped car can affect driveability.

But we're just trying to get approximate information here, right, 93forestpearl? Cuz you're gonna be doing some tuning anyway, right?

You could get a better idea if you did the test twice -- once with the new MAF upstream of the stock sensor and once with it downstream.

If you have an OBD-II MAF-equipped car available for your use you may want to use that car... an OBD-II scantool should report actual airflow to you so you don't have to know the sensor's transfer function.

Yeah, I'm just looking for approximate info here. My Leg obviously isn't OBD-II, but I'm shure I could use a car that is. I'm just kind of brainstorming since I have that MAF sitting here that I got for nothing.

I guess it also depends on what I do for tuning. Depending on how the LegaCU turns out, I could end up with the Megasquirt. I'm just trying to aviod spending $1500 on tuning equipment that I feel is very overpriced for what it is. If free5ty1e incorporates a wideband, EGT, and datalogging, I'd be a happy boy.

What I like about the Megasquirt is that it uses MAP. I'd have to get a sensor with a higher range as that one maxes out at 20psi. Soldering it together isn't a big deal. I built a couple Heathkit radios when I was little. I still know some guys in the ECE department(eletrical and computer engr.) if I need to change part of the assembly code. For about $200, I couldn't complain.

I won't need anything until spring though. I just ordered a set of Wiseco pistons, and have my block down at the machine shop waiting for me to get them because they can't bore the cylinders .020 over untill they have the pistons in their hands. I also bought a badass intercooler off of ebay for $200. 30x6.5x3.5 Soearco core. I think that will fit the bill, but it barely fits where i want to put it. It will be interesting when I get to that point. Now I just need to let my paychecks catch up to my indulgence