Tom,
Good points all, I think. Thanks for the technical insights!
In regards to a telltale boost gauge, I think it could work like this:
It would be plumbed, of course, to intake manifold pressure.... period. If the factory boost figure were say, 10 psi, measured in the intake manifold during dyno testing to determine flywheel horsepower output, that 10 psi figure would be the determining factor in the engine's eligibility at any given time. But, not quite...
Increases (or, decreases, which we are not concerned with) in ambient barometric pressure would change this pressure incrementally, as per your demonstration in the previous post, but the changes in boost, upward (say, at a reading of 2,500 feet BELOW sea level,) could be dealt with by giving the participants who run forced-induction, a boost "window" that would forgive, if you will, levels of boost that would be influenced by anomalous weather conditions; a "grace" amount of an indeterminate amount, at this point. That could be discussed by NHRA's "experts" so that a car that is legal, operating in sea-level barometric pressure, wouldn't become "illegal" when the boost goes up due to favorable weather conditions.
Those weather conditions would sometimes happen, of course, but I don't think the amount of this "leeway" would have to be very much.... not to the point that it would be something that could be taken advantage of by an unscrupulous competitior. It could be a matter of percentages; say, two percent of the maximum boost figure??? That is just a wild guess....
I have NO IDEA if that is even close to what an engine's manifold conditions might experience under high barometric pressure, but you might have a formula that could get us in the ballpark for the increase.
The agreed-upon "window" would have to include boost increases (percentage-wise) for the worst-case scenario regarding records having to do with barometric pressure "experience". Location wouldn't matter; this would be a blanket figure that would, ideally, cover any possible eventuality with regards to barometric pressure increases below "sea-level" accepted standards.
It would be implemented so that the Tech who reads the gauge is oblivious to its existence; it would just be say, for instance, a one-pound of boost value, tacked onto the original boost limit figure (obtained from the OEM source.
As a PERCENTAGE, agreed upon by NHRA Tech, it would be easy to apply to any and all forced-induction engines, and would be in evidence on the boost spec sheet as a part of the total boost allowed. It would always be a part of the acceptable boost level figure, so no one would even be aware that it was being implemented.
Is there a reason why that couldn't/wouldn't work?
f so, what am I missing, here?
Thanks again for your excellent technical advice and information. I am (obviously) not educated in this area; I just deal in generalities, so my thinking may well be flawed.
As regards your comment, "Another huge factor in intake manfold pressure changes is cam timing. Ex: Less overlap = more boost at fixed drive ratio. So again within the legal mods for stock, how do you maintain some "stock" boost level?"
I will leave that one for someone else, as I am not sure what would be fair, or even workable on that score. Sorry; my resources are limited...
Bill