Some MAF stuff for your enjoyment
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Teching In
Joined: Oct 2013
Posts: 40
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From: Christchurch, New Zealand
Some MAF stuff for your enjoyment While tuning my MAF I thought I would have a look at the transfer curve and do some thinking. My car had one of those Granatelli MAFs and I wanted to replace it with an 85mm.
So look at the first picture, this is the transfer curve of an 85mm MAF from a later model C5 than mine. I did a curve fit and the function is shown on the picture. The constant term at the right is the vertical offset of the whole curve. The next term to the left is a linear term and is responsible for the flatish region at the low end where the frequency is small. As the frequency rises the square and cubic terms have more of an effect and start to dominate.
The second picture is a curve fit to actual airflow data that I recorded during a brief run. The data is not very good, it is incomplete but illustrates the general form of the transfer curve. Notice that although it is pretty rough the function has a similar form to the first picture.
Adding or subtracting a percentage to the whole MAF table changes the constant term and so just raises or lowers the whole curve.
Anyway no real information but it helped me understand how to go about changing the MAF table.
Cheers
So look at the first picture, this is the transfer curve of an 85mm MAF from a later model C5 than mine. I did a curve fit and the function is shown on the picture. The constant term at the right is the vertical offset of the whole curve. The next term to the left is a linear term and is responsible for the flatish region at the low end where the frequency is small. As the frequency rises the square and cubic terms have more of an effect and start to dominate.
The second picture is a curve fit to actual airflow data that I recorded during a brief run. The data is not very good, it is incomplete but illustrates the general form of the transfer curve. Notice that although it is pretty rough the function has a similar form to the first picture.
Adding or subtracting a percentage to the whole MAF table changes the constant term and so just raises or lowers the whole curve.
Anyway no real information but it helped me understand how to go about changing the MAF table.
Cheers
