09-09-2014, 07:31 AM
(08-09-2014, 07:48 PM)pro_steve Wrote: The stock 90 can measure up to 577Kg/hr, the 2.2 MAF can read 774 Kg/hr.
Are you sure about that?
Do not take the max flow limiters as gospel.. Ever tried fitting one in a flow bench?(08-09-2014, 07:48 PM)pro_steve Wrote: At 5000 RPM, for example, that's a difference of 960 mg/r vs 1290mg/r. Quite a big difference really.
It is not able to measure that much, not the 2.0 nor the 2.2 sensor. They are maxed out before that. Let's just say that they are able to measure that kind of flow - how much power does that give us? Remember we do not want any smoke from it.
(08-09-2014, 07:48 PM)pro_steve Wrote: And obviously you aren't going to get all of that useable range out of it, but with some clever maths on the linearisation you can maintain smoke control down low and also up high and then get it useable above 900 anyway.
clever math = decalibration ? I know that there are some folks that tend to decalibrate the sensor by 30% - thinking it will give them more headroom. But you can not beat physics. Running decalibrated is always a bad idea.
(08-09-2014, 07:48 PM)pro_steve Wrote: If your MAF is broken anyway then it's not too much trouble to change to one of these.
True, but the 2.2 sensor will not give you much more (measurable) flow as you think.
(08-09-2014, 07:48 PM)pro_steve Wrote: When you use the normal MAF in a 2.8 housing, how are you working out the calibrations other than just the maths for the cross section, you've got boundary layers, the depth at which the sensor is submurged/actually measures the flow etc etc to work out, or does it not need to be that precise?
You do not need to be 110% accurate on a diesel since the engine will not die from a miscalibrated sensor - but using a flow bench and some logging on the car (wideband lambda) you can get a 98% match with reality. The rough work is done by using maths, the finetuning is done by using the flow bench. Once you have the first one nailed - you have them all, as long as the sensor position in the housing is the same. Offsetting it will give you a different reading.
Getting the right MAF is critical to be ableto control the smoke properly. it will not give you more power, but it will give you a better burn since you have so much more control.
MAFLess is _very_ rough, the maps needed in order to run MAFLEss have too low resolution. I see no point in running without a maf really.