Hello Chris,
If you had taken some time to look at other topic postings the subject of visa overstays has been discussed extensively.
With all due respect, and I'm not trying to single you out for special criticism, I personally find it strange that Europeans especially are the most prone to trying to find ways to get around immigrations rules and thinking that they aren't important or just don't apply to them. You're not the first and I'm sure you won't be the last either. Many Europeans make elaborate plans to come here for longer periods than permitted by law and I really can't figure out why. Perhaps you could shed some light on this for me, if you don't mind? I'd really like to try and understand this mindset of "rules be damned" which seems to be very European.
My question to you is why would you even go to all this trouble? First of all, if you'd read a bit you would already know that visa overstays here in Brazil are really no big deal, subject to a small fine (R$8,25 per day to a maximum of 100 days) and a big ugly stamp in your passport to ensure you pay it. Beyond that the only possible consequence is that it MIGHT, and that's a pretty big MIGHT at that, give another country reason to deny a visa should you travel during the life of that passport.
On the other hand, If you used up the 180 days you're legally entitled to on the American passport and visa then left Brazil only to try and return a few days later on another passport the risks and consequences are enormous. Yes, you might pull it off. However, there is a greater chance of being caught. Now rather than being able to play dumb and say you didn't intend to overstay the mere fact you try to re-enter using another passport clearly proves the contrary and also ceases to be a simple overstay and falls into the category of an immigrations crime. This can lead to some extra time in Brazil that you're not counting on... like at the hospitality of the Brazilian government with lodgings in something far from being considered a resort. This would surely be followed by deportation which would have a permanent negative impact on your future travels worldwide.
My advise, and I hope you'll see the wisdom of following it, is to either stay in Brazil for your six months, bite the bullet and leave it at the six month stay. The other option is if you are really intent on breaking immigrations laws anyway, just overstay and play stupid when you get caught or leave voluntarily following the overstay. The first is the smartest thing to do, the second while ill advised at best isn't going to get you locked up or screw up your future travel plans forever and a day.
Is there really some burningly compelling reason you must stay exactly seven and a half months anyway???
Cheers,
William James Woodward Brazil Animator, Expat-blog Team