Salut Patrick,
Welcome on board...One more "French Perv" on this forum:laugh:...
According to Superformance website, the original GT (le mans winner) was able to reach a top speed of 205 mph at 6200 rpms..basically 330 km/h.
Considering top speed capacity can also be determined from a phyics mechanicals principles.
For example, going on with the specs mentionned on the spf website :
We have :
2682 lbs
485 hp (max output)
CX 0.39
Frontal area :14.1 sq / feet
This is all what is needed to calculate how fast such a vehicle could go (not considering gear ratio), the max speed such vehicle and shape could attain.
We determine the opposite forces to motion : basically friction and aerodrag. There would be also the slope of the track but for easy calculation here, I will consider 0° slope, normal air density and a friction coefficient standard of 0.0015 not altered by speed and a drivetrain efficiency of 0.85, today we could take a 0.90 but with machining tolerances of this era better to take a 0.85 ratio.
Added a 0.003 value to friction for resistance of steering, brakes etc....
So with these value assembled together and computed we arrive to a result of 350 km/h for 484.7 hp (Rounded values). what does this means : it means that to maintain a speed of 350 km/h you need 484.7 hp of power for this vehicle, with the specs and inputs mentionned.
Converting in mph, it means 217.49 mph so a bit more than the 205 mentionned above.
This is where engineering starts : when you have these numbers and the way the car will be used, you will define your gear ratio, in the case of the original gt, it seems clear that fors engineers decided that 217.50 mph was not their target or went blocked by the gear ratio available , I don't know the story..anyway we are not too far : 217.50 vs 205 mph...
Then you will consider how fast you want to reach a predetermined speed and this will be an additional power to add to a calculation.
And fnally according to this you will be in position to define your gear ratios according to engine specs : shifting at hp peak and having rpms to drop down at the highest torque level...
etc....etc...To explain all , there would be a book to write...and it wasn't my purpose, so pllease retain :
max speed for the gt 205 mph as configured by ford, max speed determined by physic 217.50 mph, so with the right gearbox this is the max speed the car would reach.
Greetings
If you are on Paris, maybe let's share a drink one day...
Stephane
Saving you all calculations :