Data logging MAF settings with Cobb AccessPort

Denny McLain

Understand they are apples and oranges, but in this case they are the same thing as they measure airflow. I'll do a bit of homework myself but unfortunately at this point it may be a moot point. Don't believe the readings are accurate as things just don't add up coming straight out of the book of common sense.

Actual CFM
Is the flow rate of fresh air into the engine measured in cubic feet per minute (CFM). This is measured at the entrance of the air cleaner or if no air cleaner is present, the throttle body(s).

Actual CFM should correlate closely to actual dyno measurements. For example, a small block Chevy making about 334 hp @ 5500 rpm (close to what our engines are suppose to make) dropping to 320 hp at 6000 rpm using Performance Trends Race software computations will flow the following:

Rpm 2000 2500 3000 3500 4000 4500 5000 5500 6000
CFM 171 220 273 330 394 459 521 578 612
HP 118 154 188 225 263 298 322 334 319

This is pretty hardcore science which the MAF readings I'm getting do not match. Even if the hp drops some, the cfm will increase with rpm unless it's a drastic drop in hp. As mentioned from 6200 and up.....zero change in grams per second when logged.

So far I'm basically getting nothing but grief trying to figure things out as what I've learned over literally decades of doing this is going out with the baby and the bath water.

Throwing a set of 4.08 gears in the car and leaving the AccessPort in the drawer until something changes. My intentions were to throw a set of 305x30 tires on the back, lightened the car by about 100 lbs and use a few drag strip tricks in cool weather to get the car in the 12's. Putting everything on hold untill something changes as I realy do not like not being able to control things.