Keith,
As an interesting note, GM's build manual and software for the IRL Aurora
expect to see 3 lbs at >210MPH...
John
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Okay now we got the question framed with the right subject... let me give
you a bit of my experience....
We were thrashing in 03 to get the Modified sports car ready in a very short
period of time, this question came up and we decided that bigger was better
by default.... to small was not going to help anywhere on the course.... so
we added a bit of size and simply accepted the increase in drag.
Last year at speed the airbox was increasing the ambient air by about 1 lb
of boost.,... When we went back and checked what that meant to our hp it was
around 30hp more then at standard day, no boost. Obviously there has to be
some kind of fuel air ratio change to compensate for the increased boost and
every system is a bit different. Ours uses a boost referenced fuel
regulator which increases fuel pressure to the injector.
When I went back to the data from the runs I can't see a change in fuel
pressure hence the motor was leaning out on the big end.
The best reason I can come up with for this is that the air line to the
regulator got pinched, so the regulator never actually got the notice that
the fuel requirement was different. I think one of the solutions is to
increase the outside diameter of the line to provide it more rigidity to
prevent this in the future.
That wasn't even close to your question but at least provides some room for
discussion.
Keith
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