the thing with the speedometer being off by a couple of miles is because the speedometer reads the speed that your tires are going... but oviously the wind will slow you down wich the speedometer wont read it... its just like pressing the gas on 2nd gear and you see your speedoter hiting 60mph in less than 2 secs... wats not reading is that the tires are sliping and you are actually not going that fast.... same thing with the wind.... but like someone said that the f1 hit 240 and someone read the car was going 220... its because of the wind... if im doing 162 im not going to loose 7 miles... ill loose about 3 or 4 miles...

 

You can go by the rpm and do alot of math

 

Huh. The speedometer on this car seems to be slow on the acceleration or deceleration. Wind will slow you down or make you a little faster but the speedometer will read those changes unless you happen to be spinning the tires.

 

He is right.. if you can hit 6300 rpm in fifth gear you are going 176 mph... do not try and gimmie all this bullshit with the wind and blah blah, its ******* math. Stop judging your car by your inaccurate speedos...

BTW if anyone was curious, if you want to reaach 200 mph in a ss/tc, you need to be going 7200 rpm in fifth, on stock tires. with a 235/40/18 you only need to hit 7115

 

Your math is correct However.
My point is has anyone actually recorded that speed because I believe we need almost 400 whp to rev 5th gear all the way to 6300 which is indeed 176 mph. The drag on our cars at that speed is enormous. Mine feels like it slows down quite a bit once I shift to 4th at 111 mph or so. Wind resistance is a bitch up high. I was not doubting that math. i just doubt that a 280-300 whp TC can acheive those speeds.

 

Notice how i said if your car can reach those speeds... Im not saying it can because i have not had the abilty to test it out myself, but that will all change soon once i get my trifecta tune and other goodies... i am hoping to see at least 170, and to be able to beat a 360 challenge stradale from a 40 roll

 

170 might be attainable if you take the wing off the back. The problem is that most tuned TC s loose a lot of power after 5800 or so. That will limit you some. If you make it to 6K that is 167 in 5th. IDK. My cars goes pretty damn fast but I dont have the ***** to push it to those speeds on public roads.

 

i do:P

 

Damn, if you're experiencing wheelspin at the top of 5th, don't get the Trifecta tune 'cause you already have close to 1900 hp.

Factory speedos are not perfect. They are good enough to get it down to +/- 2 or 3 mph, and error gets greater as speeds rise.

 

your speedo on your dash is inaccurate.. put a gps unit inside and take a picture of 162mph you will get better responses