ERA427 You have the same problem as other guys with cobras and running a 400hp/450torkmotor. You are trying to push a barn door through the air. If you want to stay with this motor and give the car some more pickup,here are the 2 things to change, Mufflers and gears. Mufflers have been covered here with the internal size of the inlets and outlets. You will pick 20-28HP in top end if you go from 2" centers to 2 1/2". You also will need ear protection with the louder exhaust. You have an overdrive 5 speed trans. What is the rear end gearing? We need to go up in numbers from say a 3.07 to either a 3.31 or 3.54. This will give you a faster car from "0" to "100".
I have been running 3.31 gears with both motors. I do have 2 different trannies for the tracks. The trick is the keep the motor in the power band all the time between torque and HP. YOu want the motor to cruise in the torque band at about 750 rpms from where it starts and no more than 500 rpms pass where the motor HP maxes out. After this you are just wasteing motor.
You also need to remember the air drag keeps doubling every 10 mph added to the speed of the car.
Suggestions, want more power, build another motor that is aluminum to save weight on the car and a stroker in the 480-527 range. Save this motor (428)for a rainy day or resale. Other ideas are to build a windsor stroker motor. This about 1/3 less in cost and parts are easier to buy and build with. Power limit will be in the 400-800HP and 300- 675 ft of torque ranges.
Last, not sure of your driving ability, but when you start getting to this kind of power numbers, your driving skills better improve to hand this killer.
Been there,done this too. The different between 368h and 448 of torque and 540hp and 620 of torque is HUGE. Find out what the gearing is too start. I think you will be happy going up 1 higher number of ratio. You can get a Jag center section and swap over all other parts. Good luck. Rick L.
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