How accurate is calculating bhp from your MAF readings?

[GVK 0]

Ross-tech site states

 

"

Here's a good sanity check for the status of your MAF. Do a full-throttle run all the way to redline in a single gear (second works fine). Group 002 usually shows air mass in g/s. Your peak airflow should be roughly 0.80 times your horsepower. So, if you have a stock 150 hp 1.8T, expect around 120 g/s. If you have a 201 hp 24V VR6, expect around 160 g/s. If you see significantly less than that, you MAF may be on the way out. This still works if you are chipped, but "race" programs may make more power through timing, rather than airflow. Therefore, take all readings with a grain of salt."

 

I've done various logs on different cars on vag-com and calculated the bhp from it, suprise suprise it can be less than that car has made on the dyno...

 

My VR6 shows 152 g/s flat out = 190bhp Has been 200+ at Stealth evertime.

mk4 Golf R32 with Schrick 264 cams and Revo 215 g/s = 269bhp (pretty close to what it was at Awesome-GTI)

mk2 20vt with TT lump 177 g/s -221bhp

 

Any thoughts?

[dr_mat 0]

Depends on the exact make and model of MAF, and the exact calibration of that particular MAF, and the size of the TUBE it sits in!

Plus on early 12v VRs you can't read the MAF in measuring blocks, and they aren't running closed loop stoichiometric either, so you can't guarantee that air flow == fuelling == power output.

 

If you can get a *calibrated* reading of grams per second, you have a reasonable idea of power output, but otherwise all bets are off.

[dinkus 10]

My thoughts would be that your MAF's fine... as the quote says - it's just a finger in the wind type sanity check, so I wouldn't worry about 10bhp. If it was off by 50+ then it might be slightly concerned, but as the good doctor says, it's not calibrated or nuffink :lol: