Max Possible Top Speed

[Intrepidman]

Does anyone know how to do the math on this. If you have a stock 02 F-body with an A4 and 3.23 rear end, what is the maximum possible top speed you could achieve (assuming you had enough horsepower) with a 6800RPM limit in 4th gear?

Second question, has anyone ever pinned 4th in an A4 with stock gears and what kind of power would be required to do it?

[SOMbitch]

Yep I pinned mine and the gps said 161 when the limiter cut off fuel. Did 174.6 with H/C/I and boltons and the GF told me to back out....... It was 4:30am and I was scared Sh!tless a deer was going step out in the road. I am done on wide open runs unless I do an organized event like the Maxton Mile or another ECTA event....

EDIT: 161 was lid and CB only so basically stock.

[pajeff02]

Start by measuring your tire diameter. Ours is 25.6 inches, so I will use that for this example:

For every 3.23 turns of the driveshaft your tire will make one full revolution. Engine revolutions to driveshaft revolutions depends upon transmission gearing. Assuming overdrive is 0.70:1 (engine rpm : trans rpm), running the engine at 6,800 rpm means that the transmission is turning the driveshaft at approximately 9,700 rpm. There is going to be some converter slip, etc... so this is a close approximation.

With 9,700 rpm at the pinion, the wheels are turning 3,003 full revolutions per minute. Your tire circumference is the distance the tire travels in one revolution. Assuming a stock tire diameter of 25.6", the circumference is equal to the diameter times pi. This yields a circumference of 80.425" being 3.14159 x 25.6". Converting the circumference to feet (divide by 12) equals 6.702 feet per revolution.

6.702 feet per tire revolution times 3,003 revolutions per minute equals 20,126.1 feet per minute. There are 5,280 feet in a mile, so the car is traveling 3.8117 miles per minute. Multiply this by 60 and you get 228 miles per hour at 6,800 rpm.

[blkSS98]

Holy Shit!!! HAHA!!!
I can't imagine a 4th gen going 230mph

[lrader99]

this is theoretical it does not take into account for CD coefficient of drag which compounds exponentially with speed. basically you have to take your speed then figure out your surface area and CD and a bunch of other crap and it will give you a realistic number. i know personally i had my car clocked at 187, but it was way modified and slammed on the ground plus i had my own wing on the back for aero stability. Also the Factory gauges get very inaccurate above 100, there is a +/- correction factor that is built into the computer. the faster you go the less accurate the sensor gets

[pajeff02]

I agree -- the formula does not take into account drag or anything else. It would be "top speed in a perfect world".

[redbird555]

The drag has a huge impact on the top speed for example the bugatti veyron take oly 350hp to reach 150 mph it takes another 651hp to get it to 253 mph.