Anybody ever use any desktop dyno software? Also, victor heads...?

[defiance]

I just got a desktop dyno software package - Virtual Engine Dyno Pro - and I've been doing some playing around with it...  I wanted to see if anyone had any experience with desktop dyno software accuracy.  So, anybody?

My initial test was just to enter an engine I had dyno'd myself, a stock config '74 with a performer 440.  Came out saying 283hp @ 4500, 370tq @ 2750.  I'd dynod it at the wheels at 212hp / 357tq, so just under on torque, and a good bit under on hp - but those could be attributed to tranny/rear end (727/2.76) losses, maybe?

Anyway, I then set up the config I'm working on now - 496 stroker, 292 duration 550 lift cam, ross 12cc dished pistons, 10.5 compression, edelbrock heads, dual quad intake, headers, etc. - It showed that config at 503 hp @ 5500 / 536tq @ 4250, this time a bit less than I expected, but still quite nice.

Here's where I really got to wondering, though.  I made two (and only two!) changes - I changed the heads for victors, and changed the pistons to a slightly larger dish so that I'd be at the same compression with the smaller chamber.
Suddenly, it jumps like crazy!  687 hp @ 6250 / 610 tq @ 5250 - that's 150hp and over 100 ft/lbs torque just for changing to victor heads??  Can that be right?  I guess that would mean my config before was starving for airflow through the heads...

At which point I started doing some checking; victor heads really aren't that much more expensive than the performers - I was going to get harland sharp roller rockers anyway, so getting offset should make little difference, and I was getting the edelbrocks a once-over at the machine shop, so that should be similar, too - meaning there's really only effectively the difference in actual cost of heads and valves, which comes up to around $300.


If all that is true, and this software is right, that's a HUGE jump for one part... Is there any reason I shouldn't do that?

[RD]

i use dyno 2000, and this is what I got, but I have not dialed in the heads or the camshaft correctly.