Air/Fuel gauge usefulness
05-01-2009, 04:39 PM
#31
Rennlist Member
Could be because the engine was low on power, and the vane was not open as much as we see. (a stretch)
Seems also to reason that if you could get more lean'ness by opening it up,(what is more lean-ness? are we talking 1 full point of AFR?) then it stands to reason that you could open it up and gain 10% more HP by richening up the fuel regulators. sorry, more like 2-3%HP gains, as the air effects on the vane are logrithmic.
Bottomline, other folks might not see any changes by playing with the AFR screw at WOT, and if they did, it would massivly screw up mixtures at idle, for which it was designed to tune. make it leaner at WOT, and your NOX will be high at idle. Richen it up at WOT with the screw, and CO will be way high, regardless of if you saw a change or not at WOT.
Seems also to reason that if you could get more lean'ness by opening it up,(what is more lean-ness? are we talking 1 full point of AFR?) then it stands to reason that you could open it up and gain 10% more HP by richening up the fuel regulators. sorry, more like 2-3%HP gains, as the air effects on the vane are logrithmic.
Bottomline, other folks might not see any changes by playing with the AFR screw at WOT, and if they did, it would massivly screw up mixtures at idle, for which it was designed to tune. make it leaner at WOT, and your NOX will be high at idle. Richen it up at WOT with the screw, and CO will be way high, regardless of if you saw a change or not at WOT.
I never did. L-Jet fueled pretty well for the minor changes I made, mostly exhaust.
Now I'm all about LH 'n MAFs 'n stuff.
If I want noise, I would actually read your posts.
What I observed is that when the bypass was closed, the AFR richened, when it was opened a few turns, it leaned out, and again when it was closed, it went rich again. You figure it out.
Now I'm all about LH 'n MAFs 'n stuff.
If I want noise, I would actually read your posts.
What I observed is that when the bypass was closed, the AFR richened, when it was opened a few turns, it leaned out, and again when it was closed, it went rich again. You figure it out.
05-01-2009, 05:09 PM
#33
Race Car
475hp/460lb.ft
05-01-2009, 08:08 PM
#34
05-02-2009, 02:25 AM
#36
Rennlist Member
Good article, but wrong about the AFM not being able to measure mass flow. If that was true, the Bosche book wouldnt have referencef the use of barametric and tempurature sensors, only required up over the altitude of 10,000ft for fine tuning!
The only think that measures "Volume" air flow , is something like an anemometer.
. I for one, have measured the voltage at sealevel WOT and 6000rpm and that at 6000ft. mixture and mass flow were metered and measured just fine. The voltage from the AFM was representitive of the 20% air density loss at 6000ft. CFM at 6000rpm is near 500cfm, at 6000ft or sea level. the differnce is the density of that air flow. (ie the mass flow). The vane is very good and accurate at measuring mass flow. It has been used to measure fuel accurately from 170rwhp to 293rwhp with no changes to the system. So, it is extremely good at measuring mass flow, albiet via a small intake hole and vane. sure the vane doesnt have the losses that it gets credit for, but its inlet area is very small compared to most MAF meters which is its main deficiency.
The article says:
There are a few other things to note about vane airflow meters:
(1) Unlike a hot wire design, the vane airflow meter measures volume airflow, not mass. It's mass which is important, and so a temp sensor is included in the airflow meter. With airflow volume and temperature available, mass can be calculated. (Atmospheric pressure? - for really accurate calculations, it's needed as well!)
Since when is mass flow only equal to volume and tempurature?????? What about PRESSURE? (pv/nrt). For "really accurate calculations" ??? Funny.
mk
The only think that measures "Volume" air flow , is something like an anemometer.
. I for one, have measured the voltage at sealevel WOT and 6000rpm and that at 6000ft. mixture and mass flow were metered and measured just fine. The voltage from the AFM was representitive of the 20% air density loss at 6000ft. CFM at 6000rpm is near 500cfm, at 6000ft or sea level. the differnce is the density of that air flow. (ie the mass flow). The vane is very good and accurate at measuring mass flow. It has been used to measure fuel accurately from 170rwhp to 293rwhp with no changes to the system. So, it is extremely good at measuring mass flow, albiet via a small intake hole and vane. sure the vane doesnt have the losses that it gets credit for, but its inlet area is very small compared to most MAF meters which is its main deficiency.The article says:
There are a few other things to note about vane airflow meters:
(1) Unlike a hot wire design, the vane airflow meter measures volume airflow, not mass. It's mass which is important, and so a temp sensor is included in the airflow meter. With airflow volume and temperature available, mass can be calculated. (Atmospheric pressure? - for really accurate calculations, it's needed as well!)
Since when is mass flow only equal to volume and tempurature??????
What about PRESSURE? (pv/nrt). For "really accurate calculations" ??? Funny.mk
Last edited by mark kibort; 05-02-2009 at 03:01 AM.
