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Tired of modifying your engine with poor results?
If you are, consider doing a computer simulation of your engine with Desktop Dyno, by Motion Software.
With Desktop Dyno, you can figure out what modifications will actually work on your combo,
without the hassle of buying them, installing them, and scratching your head wondering why you
didn't get the same results as the ads said you would.
If you click on the image to the right, you can see a dyno curve comparison
done with Desktop Dyno. When I first built up my Capri, I was still stuck in the '60s-'70s musclecar
mindset of "If you want a fast car, you need to swap out the cam." Of course, with my anemic '86 heads,
the problem was hardly with the cam. As you can see from the graph, with this cam, the heads start to
die out at about 3000 RPM, just where the cam's starting to make some power. And here I was, all annoyed
that I had trouble beating stock 302 EFI Mustangs. I probably would have been happier with a set of 1.7
rockers with the stock cam.
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One thing I've discovered with the software is that one of the most important things you can
do with your motor is match the cam profile to the head flow characteristics. There's no one
"right" cam for a set of heads, but there are plenty of wrong ones. In my case, the cam was
way too big for the heads, and I suffered. With stock tires and 3.73 gears I couldn't spin
the tires if my life depended on it. (No, really, it's got traction control!)
If you are using Desktop Dyno, don't rely on the generic head profiles that come with the
program. They're good for toying with it when it's new, but if you want to seriously
test anything, you need to get the flow numbers for the heads you're using. You'll also
need the actual timing events and lift numbers for your cam, no guesses because
the catalog only lists advertised duration and overall lift.
Since I'm a Ford guy, in the near future I'll be putting up some Dyno files for common Ford
heads and cams. I've also got a couple for other Brand-X cars (Brand-B, actually), but if
you have some you've input and you're sure they're accurate and not guesses, go ahead and
send 'em to me and I'll post them on here.
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