[gumby79]

(But I am still struggling to understand how that helps on engine modifications, as you suggested.)

An engine that is more effectively extracting energy from the fuel being inserted will go faster by translating more power off the same fuel at the same throttle setting. EG :this would allow modifications targeting a specific throttle% setting.

If all the parasitic losses are isolated meaning not changed,then a positive or negative result in speed is to the engine modification.

especially if it is repeatable with Aba.

In my opinion motor modification testing in this manner would have to occur with absolutely no crosswind. Julian has kindly demonstrated and charted how much of a skew this is had on the Windows Up Down Baseline test

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Julian may I suggest an amendment to your test procedure.

Windows up > down as Baseline skue/ calibration run at the beginning of a test session to establish the current environmental conditions versus Baseline so that multiple iterations of a modification can be compared through time

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But a fixed amount of fuel does not equal a fixed power! It closer approximates a fixed torque. But given the influence of that on the drag calculation (^2 rather than ^3), the basic approach should still be valid (on diesels anyway)

No.
Only for naturally aspirated diesel ( ancient dinosaurs not applicable to this discussion)
Diesel is a fixed amount of fuel not a fixed amount of power measured in Horsepower or Torque ,Diesel is a variable ratio engine. Therefore can make a variable amount of power on the same amount of fuel based on how hard the turbocharger is spooling changing the fuel ratio and power output.


With a fixed fuel rate if you increase the load on the engine it lights the turbo better resulting in a higher pressure ratio going into the intake leaning out the engine changing the power output continue loading the engine and continue building boost at the same fuel position. Observation of this fact, is the dividing line between Gas and Diesel Chassie Dyno operators; gas guys go to the floor and read the graph industry-standard that works, is accurate, and is backed up at the track. Diesel Dyno operator is going is going to throttle up to the window hit the brakes and throttle up to load the turbo once the turbo is loaded the brakes are released now you have a loaded dyno test for accuracy of your all out effort, that you can back up at the track. EG a diesel tuned on a chassis dyno using Gas techniques for 9.8sec in the 9.9 bracket class( bracket race speeds/times are dictated by safety equipment limitations) will brake out (produce more power than expected and exceed the safty limmits of of class required equipment, resulting in a banned from competition until New safety requirements of the next higher class are met ).