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Old 02-27-2017, 07:09 PM
olddog olddog is offline
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Cobra Make, Engine: A&C 67 427 cobra SB
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By my old rule of thumb you are likely giving up 75 ft-lb of torque, but if you spin it to 9300 you should make the same Hp as the bigger motor made at 8200. Since you changed the ramps on the cam, you should pick up a bit more power.

I'm not sure that you are going to gain anything in the usable power range, in terms of MPH of the car, assuming that the gear ratio change has you running the same speed at maximum rpm of both engines. At least in theory you would need ~13% more rpm to put the same Hp to the wheels at the lower torque output. Wherever the torque dropped off (on the low rpm side of the torque curve) happen on the long stroke, it should happen on the short stroke at 13% higher rpm. So the usable torque range of both engines should give the same speed range, even though the rpm range of the short stroke is a bit longer.

That said, theorys don't always hold water. Since you said you already had too much torque to start with, I would bet this is going to help you out a bit. You may have to play with the rear end ratio a bit. I'm thinking you do not want to drop the ratio as much as the stroke ratio was changed. Maybe half way.

Keep us informed, I find this quite interesting.
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