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Jeff Chambers · 05-01-2002, 06:45 AM

For my combination, DD was about 55 hp off from what we measured on the engine dyno and it predicted the peak hp & tq points to be about 800rpm less than what we measured. And that was with a carbureted combination which you'd expect its math models to be more accurate at compared to a long runner EFI model.

This doesn't mean that DD was worthless though. You've got to use it parametrically to examine the effects of a component change. Start with your current combination and get a feel for how the DD output varies from what you know about your combination. Then start making changes ONE-BY-ONE to examine how it affects the output.

I used the solver to literally run through thousands of cam combinations over the winter. In the end, it was useful in narrowing in on the cam that I did have ground but I also had to sort through some very bad cams that DD actually said made more power. It'll converge to a poor solution but the computer can't recognize the fact; that's where the user's brain power has to take over.

Bottom line, DD is qualitative not quantitative but it can still be a very useful tool.

05-01-2002, 06:45 AM	#5
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	For my combination, DD was about 55 hp off from what we measured on the engine dyno and it predicted the peak hp & tq points to be about 800rpm less than what we measured. And that was with a carbureted combination which you'd expect its math models to be more accurate at compared to a long runner EFI model. This doesn't mean that DD was worthless though. You've got to use it parametrically to examine the effects of a component change. Start with your current combination and get a feel for how the DD output varies from what you know about your combination. Then start making changes ONE-BY-ONE to examine how it affects the output. I used the solver to literally run through thousands of cam combinations over the winter. In the end, it was useful in narrowing in on the cam that I did have ground but I also had to sort through some very bad cams that DD actually said made more power. It'll converge to a poor solution but the computer can't recognize the fact; that's where the user's brain power has to take over. Bottom line, DD is qualitative not quantitative but it can still be a very useful tool. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"