Ross et al:
I went back and Re-Gonkulated this thing – no way I can get the peak at 6800rpm without just “making stuff up” but I can now get:
Torq 432 at 4700 +28 from Gonk of prior dyno
Powr 490 at 6400 +57 from Gonk of prior dyno
I had guessed more advance before but Brent noted the ICL=105 on the old thread, so that’s only 1 degree advance, and the Gonkulator likes that better up high. Getting near 500hp now, within 2% which is well within the Gonkulator’s +/- range.
It is possible that a quick RPM gain on the dyno is making the peak higher by taking away a few ponies down low.
The YouTube movie, if it’s the dyno pull, is about 5 seconds to gain 2300rpm or about 460rpm/second. That may be enough to cost a few ponies during the pull, and “let go” of them on the top when the RPM’s stop going up, so the apparent peak is higher. Maybe! Again though, it’s not unheard of that the Gonkulator HP peak would be 400rpm low as that’s only about 6%. Good enough for pro bono work.
I’d try a couple different rev rate dyno pulls, eg 500rpm/second, then maybe 200rpm/second.
It’s also possible that the cam is “fatter” in the middle, I’m just working off the .050 duration. The .100 or .200 duration would help – Ford used to give the .100 duration on all their cams.
Either way, there’s a range – 472hp to 490hp, and I’d bet more on the 490hp with the right ICL=105 in there.