Ok, having read this thread: Governor? how fast can my 2005 V6 SE go?
... I've noticed a lot of people are confused on what the top speed of their Tib is and what they've obtained.
I posted up this information a long time ago back when NT.com had one of it's "top speed" thread stretches (another newbie would start a top speed thread like every other day...as if 20 of them wasn't already enough)
STOCK TIB Gear Ratios
4-speed (5 spd for I4 is the same as for V6)
Tire Diameter - (215/45/17) = 24.62 inches
Max RPM = 6500
Top Speed capable of reaching in 6th gear at 6500rpm = 153.52716538203458 mph
Top Speed capable of reaching in 5th gear at 6500rpm = 139.59879775090584 mph
4spd AUTO V6
Top Speed capable of reaching in 4th gear at 6500rpm = 165.97676051097798 mph
5spd I4 (assuming 205/55/16 tires)
Top Speed capable of reaching in 5th gear at 6500rpm = 141.07303363292192 mph
4spd AUTO I4 (assuming 205/55/16 tires)
Top Speed capable of reaching in 4th gear at 6500rpm = 153.6570131588633 mph
How did I come about this info? Well it's simple, and anybody can do these calculations themselves any time they want. Just open Google and type "top speed calculator". There are MANY sites that have little applets set up to make finding top speed, how fast your car goes in a certain gear and at a certain RPM, etc. very easy. Now how do they work?
Well, your vehicle's top speed (theoretically) is determined by a combination of the drive tire's diameter, the car's final drive ratio (or rear axle gear ratio for RWD), the transmission gear ratio, and finally the engine's speed (RPM's). These factors combined allow you to determine the fastest speed your vehicle can theoretically obtain on a flat surface. Now why do I say theoretically? Well, there are also inhibiting factors that prevent your vehicle from reaching it's full potential. These factors include, but probably aren't limited to: vehicle weight, aerodynamic drag, road/tire surface (friction), and vehicle power.
First and foremost, the vehicle must have enough power to overcome those other forces working against motion (the weight, friction, and drag). If the vehicle doesn't generate enough power for the way it's geared, it will never max out the potential of the transmission/axle and we'll say the vehicle is drag limited. As speed increases, one of these forces grows considerably...the aerodynamic drag. It becomes much harder to move air out of the way at 120 mph then it is at 40 mph. You may be able to accelerate in 6th gear from 50-70 mph in only 7 secs, but to go from 110-130 mph it will take you like 15 secs (these are just guestimations). That's because at 65 mph it takes about 12 hp to overcome drag. But at 120 mph, it takes 75 hp just to overcome air's resistance.
So neglecting these inhibiting forces, the top speeds provided above are the theoretical maximum speeds you can obtain w/STOCK Tibs assuming they make enough power. Why is the word STOCK important? Because once you start changing things about your Tib, such as getting bigger wheels/tires, getting a new transmission or drive gear, or raising the rev limiter, you increase your vehicles potential for top speed. Adding a supercharger to a stock Tib w/o changing the wheels/tires, transmission, or raising the rev limiter WILL NOT INCREASE YOUR TIBS TOP SPEED POTENTIAL. It will make it easier to obtain the vehicle's top speed, and may make it reach it's full potential if the vehicle was previously drag limited, but it will not increase the theoretical top speed.
So, if you claim to have obtained higher top speeds then those posted above w/a Tib that has STOCK transmission, drive gear, wheels/tires, and rev limiter, then you were either on a downhill slope and/or had the engine past its 6500 rpm redline. I know my 6spd has a rev limiter at about 6500 rpm, so you couldn't go much past it. Maybe you "thought
" your car was going faster when you glanced down at the speedo...which itself may be inaccurate since on webtech I believe the tolerance of the speedometer is somewhere in the neighborhood of +- 2-3%....which in the 150 mph range 2-3% equates to being off by 3-5 mph.
Finally, for those of you who still don't understand how a 4spd AUTO Tib has a higher top end than the 6spd, if you lower your gear ratios (whether final drive or the transmission gear), you increase your top end for that gear combination. For the 6spd it's a combination of a 4.43:1 final drive w/a 0.70:1 6th gear. For the Auto it's a 4.04:1 final drive w/a 0.71:1 4th gear. 4.43 x 0.7 = 3.101. 4.04 x 0.71 = 2.868. 2.868 is LOWER than 3.101. Therefore the Auto has the higher top end w/the same 215/45/17 tires. If you don't believe me, go hear and find out for yourself.
Enter in different gear ratios, etc. In real world, my 6spd cruises at 80 mph in 6th at 3400 RPMs. This calculator will say that exact same thing.
THE BOTTOM LINE ABOUT TOP SPEED: WHO CARES!
You claim to have reached 140 mph and this other person claims 145 mph... big freakin deal! Get a life and enough pointless TOP SPEED THREADS!