Contour Enthusiasts Group Archives Forums Modifications Forced Induction Diablo MAFia - How does it work?

Originally posted by ButtonPuncher:

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Sure you're improving resolution! You can increase resolution by either making a smaller MAF look larger or by making a larger MAF look smaller. Let's say that you are using a 90mm Cobra MAF. At your peak horsepower you only generate 3.5volts. You are wasting 1.5volts of resolution. If you scale the 0-3.5volts to 0-5 volts, then recalibrate your PCM for a smaller MAF, your are effectively using the whole MAF's range.

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Okay, I could be wrong in the way I was phrasing my last post but the 12v source ends up as a 5 volt reference signal for the maf, period. As far as achieving 6.5 volts, okay you proved it is possible but you are using a compressed air nozzle right in the opening! That would never be duplicated in real life, Maybe at 25psi boosted...

Here is why I think this is jacked up and that the marketing campaign for the MAFia has pickled your brain.

I don't agree that you will get more resolution by extending the voltage range in the limited way you are trying to.
It isn't the voltage range that improves your resolution, it is the number of sampling points AND the number of sampling points that you can use. You want to keep the voltage range the same and increase the number of data points to actually increase the resolution. WHat you are doing is increasing the range with higher voltage but not increasing the number of data points. Isn't that the opposite?
Here's and example:
By increasing the voltage range then scaling it back down you are increasing the measurable range at a DECREASE in MAF resolution because you are now using the same 30 points to represent and even larger range. Oh, I forgot to mention there are only 30 data points that the pcm can use; whether on 5 volts or on 7volt you still get 30 data points.
Where do you want the increase in resolution? Down low where precise fuel metering is important or up high? Fully half of the data points for transfer function are used to describe the curve in the low range anyway and that is all below 2-3 volts. Oh, and you haven't even answered the question as to whether or not you truly NEED increased resolution or rather an increased range.
Is that what you need, or do you just want your MAF system capable of reading more airflow than it is now?
I will tell you that the stock SVT maf is capable of reading 700kg/hour of airflow and that is enough for well over 300 crank horsepower. You mentioned 270 crank, well there you go. More resolution isn't required because the airflow volume is large at higher rpm and since it is WOT you only need a few data points to keep the A/F on target.

Additionally, you are going from 5-7 volts where you don't even know what the airflow/voltage curve looks like above 5.5volts as your compressed air into a small hole might indicate! To get enough flow volume through the whole maf that it will cause the sampling tube to see that kind of pressure and flow that equals what you just put into it with your compressor nozzle would be mind boggling; and that only gave you 6.5v. These functions aren't linear as you probably know, so does another volt mean another 100cfm or does it mean 1000cfm?

Anyway, no matter what you say you are still
- extending the range of the maf into uncalibrated territory
- rescaling the extended range back down into the pcm 5v expected range with the same 30 sampling points, and thereby reducing resolution at the expense of increased range
- making for a lot of expenses on the dyno as you try to figure out just what/how you will calibrate this equipment to make it work
Trust me, I spent big $ getting a pro-m into calibration and after all that money a normal lightning maf cost less and required less tuning to get it into calibration.

So I just don't get it.
But go ahead and do this and prove to us it works as I am curious how it will benefit you.