I have a brand new engine with 3,000 miles on it. I dont really see anything in the day but at night if there is a car behind me and I pretty much floor it i can look in my rear view mirror and see like a smog or smoke. I am pretty sure the car runs rich bc I have a fuel/funky smell when I turn the car off. I dont have a cat or anything and I just have a Borla exhuast. I am pretty sure its not a blue smoke which would be oil. It almost looks like the stuff your exhaust makes when its real cold outside but this is a little bit bigger puff and seems so stay together longer. Anyone have any ideas???

 

Black smoke is fuel which would be a rich condition. But if you cant see the color your not going to be able to tell. For the most part though, most LT1's run a little rich and puff black smoke at WOT.

 

Look at your rear bumper; if it's oil, you'll see oil residue on the top of the bumper.