There, you've answered your own question. Done. Next question.

Is your room cleaned?

 

That's his parent's car.

 

not sure what your responce was but thanks

 

Do your parents know you are on their computer?

Now, go clean your room before they come home from work.

 

It is not a fixed number. As noted, my 996 GT3 and my 997 GT3 RS have different discrepancies on the displayed speed vs. actual speed.

Tire wear affects the speedo readings, tire sizes affect the readings, tire pressures affect the readings.

The procedure to determine the ratio is explained already. The data acquisition systems and lap timers (G-Tech Pro, Traqmate, Race Keeper, AiM Solo, Aim Solo DL, even the Harry's Lap Timer on an iPhone, or a Garmin GPS), can help you capture the actual speed readings to determine how much the speedometer is off in your GT3.

It is a fact that the GT3 speedometer is way off. You can use it as a reference, but the value displayed on the dashboard is far away from reality, especially at very high speeds.

I used to work at NASA (space program), but the NASA I referred to here is the other NASA, the National Auto Sport Association, a motorsports club that sanctions racetrack events.

 

why oh why

 

i dont think i answered my own question if you look back through the conversation you will find that all i asked was will MYGT3 will top 200mph sorry for upsetting you but a GT3 may be out of your reach you obviously have issues

 

your GT3 will hit 193mph range.
It could hit 200mph, however you would need to remove the wing and most likey need to duct tape the gaps around the bonnet etc....

 

Bingo. I see others are slower on the uptake.

 

thanks its got the power for 200mph but you could be right with moving wing have you tried yours to that speed

 

i can tell you know imence things about racing im only trying to figure out my gt3 ie how do you work the lap timer

 

Not many places to exercise top speed.... I have toyed with it in the desert on public highways but it is not safe practice or proper enviroment.

Nevada offers a top speed event but you would need a roll bar for 165mph and a full cage for 165mph+:
http://www.sscc.us/

Most road courses in USA have too many turns to allow a large enough straight.. perhaps a Nascar oval?

 

 

im in the uk so i will have to use carrageways and toll roads to reach the maximum

 

Up to about 120 MPH, my 6GT3 speedo reads almost exactly 5% high, as verified by GPS. Haven't checked it any faster than that.