I had a 360 magnum 380 horse engine in my 72 Dart.I had 3.91 gears with a mild converter in it.I ran it one time and ran 13.07 @ 107.89 mph.I had planned to up my shift point each run to see how it ran,but i only got the one run.5500 rpm was where i started at which was way to low.I'm sure another run would have put me in the 12's.235/60 Firestone Firehawk tires and 2980# car weight.