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TS4l
06-28-2005, 02:47 PM
Hey I was just wondering what type of AFL%'s on their SAFC's others with the Z32 are getting, in comparison to their actual HP numbers. I know you can't figure out exactly what you HP would be just by knowing the peak AFl% but I would like to see the %'s compared to hp. Just curious and bored at work! I'll post mine next time I get to the dyno, hopefully at the end of the week. My AFl% is usually at around 72-75% on a 60 degree night!

kovert
06-28-2005, 03:51 PM
Hey I was just wondering what type of AFL%'s on their SAFC's others with the Z32 are getting, in comparison to their actual HP numbers. I know you can't figure out exactly what you HP would be just by knowing the peak AFl% but I would like to see the %'s compared to hp. Just curious and bored at work! I'll post mine next time I get to the dyno, hopefully at the end of the week. My AFl% is usually at around 72-75% on a 60 degree night!

im at 72-73% with 390whp-400whp

if the z32 maxes out at 550whp, 73% would be 401whp

asad
06-28-2005, 08:59 PM
if the z32 maxes out at 550whp, 73% would be 401whp



I don't think it works like that. I haven't tested it, but my guess is that the S-AFC "percentage" is just a percentage of the 0-5V output, not a percentage of the amount of airflow that the meter reads -- remember that the MAF is nonlinear, so going from 10% to 20% is a smaller change in airflow than going from 70% to 80%.

Asad

90s13drifter
06-28-2005, 09:40 PM
The z32 maf reads like this.
http://www.streetneeds.com/uploads/dragva/blah.JPG

TS4l
06-29-2005, 09:07 AM
Thanks that is what I was wondering, I knew it wasn't linear but I wasn't sure exaclty how those percentages compared to HP numbers! Plus there are many other variables like compression ratio, intake temps, etc that would make a difference even with the same amount of air, but I just was curious to know more. Thanks guys!

Kingtal0n
06-29-2005, 02:10 PM
Thanks that is what I was wondering, I knew it wasn't linear but I wasn't sure exaclty how those percentages compared to HP numbers! Plus there are many other variables like compression ratio, intake temps, etc that would make a difference even with the same amount of air, but I just was curious to know more. Thanks guys!



You are confusing volume of air, with mass of air. The maf measures MASS of airflow. that takes into consideration air temp and altitude (density) on the spot. a specific amount of air mass will always have a potential of a certain horsepower figure... Things like compression affect that only by changing the motors Brake Specific fuel consumption... or the amount of power a motor extracts from a given air/fuel ratio. You still have the same overall potential of horsepower worth of mass of air... thats why MAF sensors work. If you give me a specific mass/hour flow rate of airflow (for instance Lb/min as you find on most turbo maps) and a motors BSFC number, I can tell you how much BHP that motor will make at the given flow with some simple math. so can a MAF sensor, except it doesnt care about BSFC it just tells the ECU which in turn decides how much fuel to inject based on programming.

_Def_
06-29-2005, 02:29 PM
The compression ratio changes the thermal efficiency of the internal combustion process. That does limit how much HP you'll make from a given massflow of air.

Also, the volumetric flowrate is a consideration since you'll have drag induced from increased volumetric flowrate when it's hot among other things. That's why your MAF voltage % goes up a bit when it's cooler at night versus during the day. It's just easier to move denser air, even though the setup is the same.

TS4l
06-29-2005, 02:52 PM
Thanks guys, this is very informative information. Exactly what I was trying to better understand! Thanks, Jason.

rn240sx
06-29-2005, 07:26 PM
Hey I was just wondering what type of AFL%'s on their SAFC's others with the Z32 are getting



Im at 15 psi and im reading 49-50% on the afc for my MAF.. Im guesstimating ~300 whp...