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Old 04-22-2021, 08:21 AM   #19
Jack Shaft
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Join Date: Dec 2019
Posts: 1,196
Default Re: Max Speed of a Model A with 26% OD and HC Head

Quote:
Originally Posted by Synchro909 View Post
Without getting into the details of the physics, it takes a certain amount of power to push a car along at any given speed. As the speed rises, the resistance increases till you reach a point where the available power is all used to maintain what is the maximum speed of the car. So long as there are no silly gearing issues etc, O/D or not will not make much difference to the top speed. The O/D does not increase the power available. The HC head makes a bigger difference.
That said, if you want to travel at say, 60 mph, the car is happier with the O/D. Things are not so busy under the hood.
The model a powerplant will handles a 2.90 or so to 1 final drive ratio,especially if you can split between 3.78 and 2.90 easily..2.90 allows you to keep the engine in its torque band at a higher speed so in essence OD does make a difference in useable,dependable top speed.
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