proving performance modifications

["Ian Lomax" <ilomax@domain.elided>]

From: "B Shuler" <ypp86w@domain.elided> writes...

Oddly, yesterday I was killing time at the magazine rack of the grocery
store and saw an article in the current issue of CarCraft magazine where
just such an experiment was conducted on their beater '68 Sattelite.  Along
with other low to no-buck mods they mounted a coffee can scoop under the
front bumper and ran a flexible four or five inch dryer vent tube straight
into the air cleaner.  Before and after runs with that modification alone at
the drag strip showed a measurable improvement of 0.13 seconds to just under
18 seconds ET. While ET is not a direct measurement of horsepower, and a
Detroit iron v-8 is not an Alfa, the modest seven-tenths of one percent
improvement jibes with my own experience better than some of the more
fantastical notions previously offered.

Given Ghaham's taste for measurment over speculation as in his excellent
previous post on valve springs, I look forward to hearing of any experiments
along the same lines with Alfa engines.  I would actually be very surprized
indeed to see ten percent improvement but only a test can truly tell.

Bryan Shuler
Austin TX
<snip>

This is the kind of information I like to see.  Actual test results.  I was
driving my spider around on the evening of July fourth, and it felt pretty
sluggish.  I had been stuck in traffic after a fireworks display, and the
engine got nice and warm.  Once traffic started moving the car just didn't
seem to be up to it's usual tricks.  Half way home I remembered that the cold
air duct was off, because it has split.  The next day a little "100 MPH" tape
fixed it.  It wasn't a 10% loss, but noticeable to me.  OK, so that's not
really measurable...

The point I originally wanted to make, is that I don't trust a performance
claim (especially "performance chips" coming from a former calibration
engineer) unless I can prove it.  The last time I modified the Verde, I went
out and found a nice flat stretch of highway late at night (flat aint a
problem in Detroit!).  I ran five 60-80 MPH 5th gear acceleration runs.  No
worries about wheelspin, gear shifting, and other variables that can affect
acceleration times.  I did this before and after the modification, and
averaged the times.  The result?  About a two second improvement, on a 12
second run.  Not bad I'd say.  I'm sure there was still room for error in my
testing, but I'm confident that the "seat of the pants" improvement I felt is
real.  One of these days I'll write this up for Craig's GTV magazine that
seems to be lacking submissions.

This would also be an easy way to test these cold air and ram air effects.
Maybe I'll try this in the Verde on the way to Pittsburgh tonight...

Ciao!
Ian
88 75 3.0 (slightly tweaked)
71 Spider 1750 (going from tweaked back to stock slowly)
Ann Arbor, MI

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