What does the first sentence of rule 4.CC on page 46 state?
DW
Of course since it is likely no one has ever thought of this (the oil pan thing) and the rule really was written for "body" modifications you might have gotten away with it.....
But now the cat is out of the bag with the impound guy...
Besides rule says around or within the car, not under-picking nits here
(oops- inspector says "my interpretation is... you lose)
Along line of some of the prior posts. Rake "generally" is helpful compared to a flat stance. But you can over do it so that not only you don't get the Drag improvement but the frontal area increases, a double negative whammy. Wind tunnel or lot of testing to prove what is best for you. I have been involved with a /GMS car (Bonneville Bugeye- see build thread) on which we do have wind tunnel testing. We clearly improved the drag numbers with a bit of rake.
Keeping as much air from under the car (irregular, poor flow) usually is good for lots of reasons, but as an air dam for a "50's car is not likely a factory item (understatement there), lowering the nose/whole car is about all you can do.
Taping seams, the grill, radiator etc are not legal as has been pointed out. However, sealing the hood well to keep the flow down and out rather than through big cracks above can be helpful.
Cold air to the engine of course can help, if can be done without an aero penalty. At least on some cars a small hood scoop (for cold air- ram effect is whole different issue and topic, covered here elsewhere at length- may have very little drag penalty. At least as shown in a tunnel on a well known Camaro. Lot of talk about the hot vs cold performance above. My car with efi (so theoretically compensating for temps and density altitude mixture wise) as stated previously ran faster late in heat of the day than early in am. And it was among the best aero shapes out there (mid '80's trans am). Again this supports the drag vs HP argument about density that has been discussed above.
See also the thread on rake in the aerodynamics section:
http://www.landracing.com/forum/index.php/topic,12933.0.html