I am not going to dispute anything but have you considered aerodynamics, wind speed and direction, roof up or down and road surface .Attaining top speed on a rolling road is theoretical speed not one that is obtained on the road/track.
Point well taken. My post was simply to address if it was even possible to attain 171 mph that the owner's manual states based on gear ratio and maximum revs. No factors of drag (aerodynamic, nor drivetrain, nor rolling resistance, etc) was taken into consideration. The amazing thing is, I must have a seriously messed up speedo because when I had my little jaunt up to an indicated 145, the engine was pulling strong and there was quite a bit of pedal left. I had the top down so arguably, this would have been the least aerodynamic situation I could muster with out taping card board boxes to the body of the car. I think someone needs to volunteer to do a real world test. Any takers?
Oh yeah, Kenyon, you're not eligible for the test because your car can kick the rest of our stocker 348's butts! Mike
Ah, one thing to keep in mind fellas is that the combined wheel/tire diameter will increase with speed. Even low (35/40/45/50) profile rubber will expand and get "taller" at higher speeds - can be as much as a full six or seven percent in the 150mph+ range. So, given the horses, the car will go faster than the static/slow speed rpm v. speed formula suggests.
I have been hearing that argument since I was a kid driver, but I have never found any basis of factual evidence to support it. In all the years R&T showed test results, and in all the myriad of cars tested, not one test I have seen shows any difference. R&T always showed speed per 1000 rpm in high gear, and you could easily compute thier top speed readings vs rpm back into the rpm per 1000 and see no difference. Speedos can be checked for accuracy by driving at a steady 60 mph for one minute (10 is better) and making sure the odo reads one mile (or 10). You can check speed at the same time by reading mile markers and distance while measuing time with a watch with a second hand. You can read off speed at 1000 rpm in high gear, and easily calculate your expected speed at a higher rpm.
Krowbar, the analysis is quite readily available from a variety of sources including, obviously, the major manufacturers. You can find the growth specifications for any commercially made tire relatively easily, and, again, the typical range is 5-7% for tires speed rated for, and tested at, Ferrari top speed ranges. It's standard testing for any new tire and required disclosure under DOT approval processes, specifically, the National Highway Traffic Safety Administration. Similarly, it is mandatory disclosure under the European regulatory schemes, the most strict being Germany (TUV). Look back through some of the R&T Top Speed test write ups over the years and you will see mention of this phenomenon with regularity. A little research would serve you well.
Holy cow, son of a gun!! Check this out, if you assume (i conservatively estimated a 5% increase in diameter, although it would seem likely that the wider the tire, the more increase you may experience) Again, no consideration for resistance (air nor rolling) taken into account here, but if you adjust the calculations (all others the same, same max revs of 7700 for stock 348, and same engine revs to wheel revs) it now works out to max speed of 172mph (171.9). So...assuming that the car is capable of reaching max revs in 5th gear before the drag limits its speed, it is physically possible to attain 171 mph in a stock 348. Who is going to try it?
