What Airflow Rate Do You Guys Hit At WOT?

[jfpilla]

Those figures sound more like a grams per cylinder value, grams per second should be up around 300.

The maximum grams per cylinder under perfect conditions on a perfect engine can be be calculated using the following formula:

m = PVM/RT

m = mass in grams
M = 28.96 grams/mole (molar mass of air)
P = (use atmosphere: 101.3kPa)
V = 0.708 (5.7/8) liters per cylinder
R = 8.314 constant
T = IAT (Use standard temp: 21degC = 273.15+21=294.15degK)

m = (101.3*0.708*28.96)/(8.314*294.15) = 0.8493 grams/cylinder

The closer you are to that figure (normally aspirated) the better your engine is working.

Regards
Paul

Paul,
Going above the calculated number is good?
I just looked at 2 dyno runs and 2 track runs. My number with a 6.0 liter and 22* is .88512. IAT at 2 different tracks a weekend apart was 22*. In both cases my best times were identical. The cylair in both cases was .96 1st gear, .91 2nd and 1.01 3rd. One dyno was done on the AM of one track run. It produced 7 more HP and 19 more ft lbs(and best times) than a dyno run a month earlier, which only produced .81 gms/cyl. Does this all make sense?
What could have produced the lower gms/cyl and lower power on the first dyno?
Regards
Joe

[Blacky]

The cylair number is calculated by the PCM based on MAF (or MAP/RPM/VE table in SD mode). Did you change anything in the tune between now and then?

Different ambient air pressure (altitude) or temp would cause a difference.

The value I calculated is the mass of air that will fit into a cylinder at STP (standard temperature and pressure). If either of those change then the mass of air will also change.

Paul

[DramaFoYoMama]

I didn't know it used the VE table to calculate that. I'm running lean across the board, which means it should actually be hitting higher, correct? If so that brings me even closer to my max theoretical flow. This makes me beg the question more, what the heck?

[jfpilla]

Paul,
I changed MAF values based on Dynair. It lowered some.
Regards
Joe