Steve, you're spot on with some of your insight. There's a couple things I'd like to comment on:
Thanks for the follow-up Jason, but a few comments in return: (Note: I use “terminal velocity” knowing that it more correctly describes the max speed in free-fall due to gravity. )
“For example, at high speed where a car is aero limited, it's actually weight that matters little, and power that primarily determines acceleration.
To summarize, at low speeds, power to weight ratio dominates the acceleration rate. At high speeds, power to drag ratio dominates the acceleration rate. “
I said:(Speaking of variables on the highest velocity straights)
“Aero drag is certainly the greatest potential factor at those speeds...
Generally speaking, with cars of relatively low power, aero is likely the biggest variable at higher speeds (above about 85, certainly by 5th gear) and power/weight more important at lower speeds.”
I see no basic difference in the meaning of our statements, do you? But, I think my point about relative importance of aero vs power at those speeds is also accurate.
“As we approach terminal velocity a few HP makes very little difference, the drag is just too great. Any clear advantage in terminal velocity is almost entirely aero.”
I say this because of course the “value” of a single HP diminishes dramatically as speed increases AND as torque multiplication decreases with each gear. On the one hand, all else being equal then sure, an extra few HP is (by definition) the only difference so it’s really important, but in absolute terms +2hp will have little impact on acceleration as you approach terminal velocity or in TV itself because of course drag increases at the square of velocity and the gearing sucks. So, the faster we go the more likely I am to prefer a very small aero advantage over a small power advantage at that moment. So my point as relating to your data where you indicated aero was set the same for both, was that the ACTUAL aero differences were likely to have more impact at the highest speeds than is the known small power difference, potentially rendering the comparison graph less accurate at the very speeds being discussed at the moment.
Do you disagree with any of that?
As for the rest from there down, I think we are in total agreement. Each car has strengths and weaknesses which come into play under different conditions. One you didn’t mention but of course know and is clear in the data is the higher RPM shift points for the 1.6, which is the only thing that keeps it close. Because “low end torque” has for many years dominated these parity discussions (an absolute obsession for one individual in particular!!) I always make a point of noting that having an acceleration edge early on a straight is better than having it at the end. Besides helping you “get a run” on the guy ahead or break the draft of the guy behind, or win that sprint to the finish line, you get to use those extra MPH a little longer. In almost every way it makes “racing” easier even if the ultimate lap time is identical. Anyone who has driven a 1.6 very long has probably had the experience of being checked up by an NB, intentionally or not, and watched them pull away out of the corner. It requires a little different mindset to stay close and keep the pressure on without getting balked.
And I think we agree on all the pros & cons of real vs simulation data. My only point there is that it’s much easier to test the impact of changes to the SAME car than to compare the “absolute potential” of two, even very similar, cars because when they are SO close even the smallest difference not accounted for with your inputs can distort the results and conclusions.
I think that covers it. Other than perhaps a slight difference in the relative importance of a couple HP vs aero at or near terminal velocity, is there any light between us at all?