Quote:
Originally Posted by gtfoxy
I get what you’re saying. & even agree to a point.
It is, however, what you touched on is much more important, repeatability in a consistent matrix of comparison. What were your induction points before the mods? Remember also atmospheric density is a factor in actual MAF calculations. Simply looking at someone else’s MAF readings is a bit of a misnomer. A person on a dry winter night at sea level is going to have drastically different reading than a hot humid day in Denver Colorado.
The other side of efficiency is valve curtain, or more over duration/lift/lobe acceleration as well as opening closing event points, in relaton to TDC/BDC, & given engine dynamics.
The main thing to realize is VE is also a function, to a point, of spacial displacement over time, or more over not piston velocity but piston acceleration. In other words the faster the piston creates cylinder vacuum the faster the that negative pressure is transferred to the incoming air molecules. Someone even mentioned a compression test, I even say a leak down would be in order, in truly diagnosing a possible issue.
That being said, you, personally, could have an issue with cam timng, which I alluded to before, & that you acknowledged, that could be causing you a detriment in VE.
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There is another PID in GEN V engines that has very limited information but I believe to be a good "summary" of weather conditions although I can't prove anything since there is no documentation about non EPA/emissions GM/internal only PIDs, but "Air Density Torque Multiplier" is a PID that puts out a number usually close to 1, in my last log it was .9922. I haven't looked at enough data to confirm but I would assume this uses all of the new GEN V airflow estimation features like the humidity sensor to give basically a correction factor. So when someone reported so many grams per cylinder (gpc) we could multiply it by the air density torque multiplier PID, so looking back at my log my peak gpc number of .870 occurred at 5913 rpms and is basically more like .870*.9922~.86 when "corrected" back to a normalized (assuming its SAE standard temp) environmental conditions for a comparison with someone elses gpc number.
Also can you explain more about what you are saying about spacial displacement over time? I don't see what piston acceleration has to do with anything, and to me I see VE more so as a "dynamic" or "effective" displacement, which is time dependent. I see "tuning" an engine (bigger cams, longer/shorter intake runners, headers, etc.) as just doing everything at the right time, or matching its "resonant frequency", just like when you push someone on a swing you want to push them at the right time, the time being when you push in the same direction of their current velocity. This is most "efficient" because you want to do you work/energy input into the system at the right time.