[olddog]

Thanks Jac.

One of the several things that got me thinking about this was another club cobra members dyno chart. The VE was still running flat, but the torque was falling off, as the rpms went up. When the VE stated to drop the torque dropped much faster. I have since seen several other dyno charts that showed similar results.

It seemed to me that if the VE is running flat and the toque is dropping then the most likely reason is that the timing is not right.

The Ford ECU timing tables does add a few more degress of timing from 3500 up to about 4500 or so for the 5.0 engine. This is another thing that has got me thinking. When you are no longer limitted by centrifugal weights, springs, and vacuum, and actually have a computer to work with, you are now free to do pretty much anything you want. You can make the timing curve go up or down in any shape you want. The issue is you have to understand what the engine needs, or you are going to waste tons of dyno time trying to figure this all out.

A third point, I built a spread sheet to calculate the time it takes for the crank to move from the point votage goes to the plug until the crank gets to TDC. Here is what I found:
At 6^ timing and 600 rpm it takes 1.67 miliseconds for the crank to go to TDC.
At 35^ timing and 3500 rpm it takes 1.67 miliseconds for the crank to go to TDC.

So it looks like the mechanical (or EFI WOT) timing is based on a fixed lag time for the fuel to burn. However if you carry this to the next logical step then you need:
At 60^ timing and 6000 rpm it takes 1.67 miliseconds for the crank to go to TDC.

But this is not the case, as most engines will stay at 35^ at 6000 rpm. If you calculate where the crank is at after 1.67 miliseconds it is at 25^ after top dead center. So either the burn rate changes dramatically or a lot of Hp is lost due to less than ideal timing. At this point I suspect a little of both is going on.