What are the pot odds required to draw at a backdoor flush?

[chson]

If you need one more card to make your flush basically need at least 4.22*bet in the pot to make a correct call. What would you need for a backdoor flush?

[BruceZ]

Click "search" link above, select probability forum, type in "backdoor flush", and search "all posts". You will immediately find a ton of posts about this, many of which have extensive discussions.