Camaroholic

iTrader: (1)

Well, I felt like playing on the computer the other night, so I whipped out the cam card for the new solid roller cam, the flow sheet for the heads, and entered it all in to DD2K. It wasn't terribly far off.

My cam is about a 242/242 .650/.650 114.

Throwing all this in to DD2K, I went to the iterator. I tried various timings, and it came up with a 241/243 as making 'the most power' with .650/.650 lift.

So then I iterated again, varying lift this time. Now, it comes back saying that .490/.630 is going to make more power than a .650/.650 - by a significant amount (~25 hp).



Any idea as to why it does this? "I'd have thunk" that more lift = mo powah. The heads don't stall until above .670 (LS6 GTP). So why does DD2K want to waste .15" of lift? Is it the 346 cylinder filling properties?

Just curious. I know, "grain of salt", DD2K is a cheap program, but it's a toy, and kinda fun to tinker with.

-Andrew

BurnOut

iTrader: (1)

The thing that I have found that DD2K doesn't take into account is port velocity. Hell, it doesn't even ask for the volume of the ports- or the valve angles. It could very well be that since DD2K was created when 18* heads were pretty much the hot ticket for SBC's, the software assumes that in order to get intake side flow numbers like you entered your port has to be HUGE, and therefore your port velocity for $#!+. It may be "thinking" that limiting intake valve lift like that would increase port velocity, and induce a sort of ramming effect to fill the cylinder.

Or I may be completely full of crap. Your pick.