what would 400 flywheel hp be ta the rear wheels

 

330-360, depending on automatic or manual transmission.

 

It is the collective assumption that a manual eats up about 15% of your power, and an automatic, about 20%.

400-15% equals 340
400-20% equals 320

So, I would have to say it would be between 320 to 340 horsepower at the wheels.