TrinaBabe

iTrader: (3)

I was hoping that someone may have a datalogger (Like an OBDII) logger that can log both MAF hz and some sort of true airflow measurement so that I could come up with a Hertz -> airflow calculation or better yet, if someone has already done this for me

I am trying to figure out roughly what my airflow is not the damned hz readings... they are worthless for me to compare to another vehicle (Non-Evo). Please if someone could help me out I would greatly appreciate it. I am also curious to see how accurate/inaccurate the MAF readings are becoming now that I am reaching over 2900hz. Anyways thanks!

l2r99gst

iTrader: (2)

The HZ reading that you get from a Karman MAF will not directly correlate to a mass airflow. The Karman HZ is a volume airflow, thus you need the temperature and barometric pressure to calculate mass airflow.

The stock ECU uses the barometric pressure and intake temperature at the MAF to calculate mass airflow. Sorry, I don't have the equation.

Eric

silverofs

iTrader: (3)

i just switched to a aem from a flash/afc setup i'm also seeing right around 1900hz i will see what my aem reads for airflow & let you know.. dsmlink was great for that it just gave you the lbs per minute for you..

l2r99gst

iTrader: (2)

I used DSMLink, too, and it was great because of that. The ability to read OBDII and directly from the ECU is something that other EMS's don't offer.

Anyway, here is a link that I found that sort of explains the calculation.

TrinaBabe

iTrader: (3)

I know it has a few variables but they could be guestimated quite easily to get an idea. Alot of the people using the DSMLink know this because they have locked thier intake temp to a set number. This will throw off the values slightly but is good enough.

Pretty much I am just looking for the calculation of at least a number of points that I have both values for, ie: 40hz @ 850 rpm (Dont know is RPM matters or not) @100 degree intake temp and sea level = xxx g/sec or any other airflow measurement. If I can just get a bunch of these different samples I will create my own calculation that is close enough for what I want. Thanks!

TrinaBabe

iTrader: (3)

Please do for me silver,

Try to get a very large range of data so I can graph it up and use it to make a calulation. For some reason it seems that no one has already... or if they did they didnt seem to post it up on the net anywhere

To get the volume of air I think I would need to use the F = K(V) formula but we need to know what K is. the constant that mitsu uses to get to the V which is velocity. With the velocity we could probably figure out the size in which it is using the measure of velcoity for in which would give us the volume of air (If you cared you could plug in the temp and pressure part or just use guesses.. sea level and 90 degrees?) Hence, if the velocity is 1ft/minute in an area of 1 sqaure foot we would achieve 1CFM. Or 50 ft/min in an area of .5 sq/ft we would have 25CFM. Like i said my math is bad but maybe someone can help me out here

l2r99gst

iTrader: (2)

The reason that some people using DSMLink lock their intake temps is because they are using a hotwire GM MAF. The MAF Translator does the same thing (locks baro and temp). The reason that your airflow will still be accurate is because a hotwire maf measure MASS air flow, not volume airflow like our MAFs, so the baro and temp could be locked to any arbitrary number. I used a GM MAF in my Eclipse.

You're right in the fact that you may be close, but you do need to use the absolute temperature, barometric pressure, and find the velocity to really get an accurate result. However, if you just want a 'ballpark' guess, then yes, you can pick a sea level baro and whatever your intake temps are.

Eric

joeymia

iTrader: (6)

I am pretty sure you can get those numbers with the MAFTpro. But what would the point of keeping the MAF once you have that

EvilDylan

iTrader: (3)

just for future reference, the Hz is called a frequency.

it just sounds wrong when you say "i need to find out what this hertz means"

no offense.