how accurate are these things, and how can they be fooled?
Well, I know of one NHRA record (both ends) that was set by a car with an oversized engine and the tester didn't catch it. This was at the Indianapolis Nationals in, I believe, '63. I had accompanied the owner and builder (now deceased) and we were chatting when he mentioned the engine's bore and stroke. I had my pocket slide rule handy (no electronic calculators then) and, for the lack of anything better to do, calculated the displacement. Uh-oh! The engine was too big. I told the owner (he had already won his class and set the records) and he spent the next few hours sweating profusely!
The engine passed! So much for the accuracy of those testers.
(My friend was so dominant in his class that those extra cubes wouldn't have made any difference as far as his elimination win was concerned, but, of course, they made it that much harder for someone else to set new records.)