I own a 09 G37 Vert. Nightmare of a story with this car.

The Engine was JUST replaced due to low oil and it seizing. No warning lamps, just died on me one day to make the story brief.

The new engine which is an entire long block gives me a slight vibration outside of the normal noise/vibration felt from day to day driving. Under acceleration especially between 2k and 3.5k the engine sounds as if it is out of sync. It doesn't sound smooth. Think along the lines of a slightly out of balance wheel. Its more of the noise I am hearing and vibrations at idle.

Is this because the engine has less then 50 miles on it and still needs to break-in? Or i am screwed with another major issue?

I call the dealer and he tells me.. Are you ready everyone... "You had a short block before, now you have a bigger long block." Really..... So my 3.7 is bigger then the one i had before??? Unreal..

 

Sounds like two things. . . A) very stupid person at the dealership you spoke with (short block is just the block while a long block is the block with the heads on it as well. . .) But as far as the vibration issue more then likely it was a newer tech replacing the engine, and while unbolting he allowed tension on the mounts while engine was coming out and stretched or tore a mount easy way to tell is pop the hood, start the car, have someone tap the gas don't hold just tap and the motor should move but should not have a large amount of motion mounts should allow for flex of approx. 1/8 inch

 

If they pulled the engine and transmission as a unit which is common,they may have not marked/indexed the driveshaft and they installed it in an unbalanced position.