Norm Peterson

I've got top speed numbers right in the same range, working it up from a wide variety of basic inputs as an acceleration simulation (when acceleration → zero, that's top speed). Been at this one quite a while.

I do expect the power curve to soften between 5000 and 6000, but not to go completely dead-flat. A 5 - 10, possibly 15 HP increase once past 5000 would make more sense because sudden discontinuities don't happen without a reason. I suppose that Ford could have artificially made that 'flat' in the power curve happen, though I can't offhand think of any good reason why they would.


Norm

Dino Dino Bambino

The reason is the stock cams were designed primarily for good low/medium rpm torque. Thanks to VCT, the cam timing is retarded at higher rpm to extend the power band and provide good pulling power up to 6000rpm, but there's still no escaping the limitations of the mild cam profile.