This is likely a pony. If you want to get technical, a Y is sometimes considered a vowel. That is used as a diversion to get people to ignore the most obvious answer. Also, saying that it has a P and an N in it and that vowels are left out does not imply that there are no missing consonants.
No, you cannot get a word with 8 letters that doesn't have any vowels. It's impossible, but you can get a 7 letter word without vowels, which is rhythms. There is, however, several obsolete words without vowels; symphysy, for example (which means the union of two bodies).