125 on my 370z

went 165mph 2 weeks ago which is around 5mph more than what I did last summer...

prolly like 85

My Young and dumb numbers:

83 Toyota Supra - 140
72 Datsun 240Z - 160
02 Yamaha R6 - ~174

155 in the nismo. 189 cbr1000rr however bike speedos r usually off I would say close to 175. I will never top out a bike again.

Hi, I've done with my 8 months old 370 to only about 160km/h and that equal to about 99miles/h. The aerodynamics do not allow me to go any further as the front was really starting to float and the steering is so light that i have problems maintaining a straight line without weavering abit. I've read that somebody here also have the same problem with their Z but most do not have that. So is it something wrong with my Z?

At 99 mph the car should still feel very firmly planted, yes. My experience is with the sport model's front spoilers (the long under-chin plastic spoiler that faces straight down, and the two little air dam flaps in front of the front tires), but honestly even if those were removed I wouldn't think you'd feel any lift at 99 mph. Is the undertray off the car maybe? (the one you remove partially or completely for oil changes?).

Hmm never thought of that, i'll look into that. Sorry for asking again, any idea how long the under tray extent to? Cause i don't know if the dealer took off some of it when i got the car. Hey thanks for the advice Wstar, in the meantime im looking for a set if front lips, hope it make things better.

I have had mine up to 125 mph a few times and it is very smooth.

It's a single large, roughly rectangular piece of black plastic on the underside of the car, covering the bottom of the engine area. Has 16 bolts all around the edges, and 3 round plastic clips in the center. Some places may remove the whole tray for oil changes or to do other services, but a basic oil change can also be done by only removing the rear four bolts and folding the rear section of it down temporarily.

Haven't had any issues even up to 120 mph.

Thanks Wstar, appreciate the help. Will check today ;-)

ok........ fastest ive ever gone in my Z so far..... 145 mph in 6th gear, i didnt even realize my Z had a 7th gear till i accidently flipped it again, and it popped into 7th gear... but by that time i slowed down considerably, 145 mph in 6th gear, not knowing i could have alot Faster, if i flipped it up another gear.......

145 mph could of been 165 to 180 (depending on different variables)

It's not about what gear you're in, it's just about coefficient of drag vs power to the wheels (or if your aero is bad, you could lose control of the front of the car rather than just being "held back" on speed by aero).

On your (7AT) car if we take say 7400 RPM as a maximum, 4th gear tops out at 123mph, and 5th at 174mph, with 6 and 7 going to 202 and 226 respectively. However, the stock ECU has a speed limiter that will limit you to around 155-160-ish regardless of gearing. And even if you had that limit removed, without some serious power and aero upgrades you won't get very much further than that just due to the aerodynamic "drag limit" your car faces.

I highly don't recommend coming anywhere near these numbers on a public road. Most people really don't have a firm intuitive grasp of the braking distances and effective reaction times at these speeds. For example: taking reaction time, speed, and traction into account, in the best case from the time your eye catches a problem to the car being at a dead stop is going to be well over 1/4 mile if you start at 160mph. You may fail harder and take even longer to react if you're not on the edge of your seat scanning every inch of road way out ahead of you.

I know people are going to do it anyways, I've done it in the past on various cars as well. I'm just saying, be careful. Don't run that kind of speed with any cars near you, especially within 1/2 mile -ish to the front of you. Absent-minded (or suddenly freaked out) drivers will change lanes right in front of you at less than half your speed, while panicking and slamming on their own brakes as well. And if you can't see that far ahead due to curves or hills, you may as well be driving blindfolded.

Well written post wstar, always good to be extra safe :tup: