True not really much left stock. The 1st time I did that was bone stock, 2nd with intake/plenum/test-pipes/and Injen exhaust. It felt like it would have gone another 5-7 mph on that stretch of flat road that I was on when I recently did this again. FWIW, I have seen videos of a stock C5 vette, not a Z06 hit 170mph on the speedo, dont know what it actually was, but I believe a Z06 under ideal condition could hit closer to 180 than the 171 claimed. As far as magazine or manufacturer info goes, I think top-speeds are a fuzzy topic...most may not tell the truth, or most may truly not know, and just use a very educated guess. They prolly think most people wont "test" their figures.

 

Because of the German manufacturers' political decision to limit top speeds on the Autobahn and thereby reducing emissions. It is over a decade old and all German car makers adhere to it except Porsche and several tuner firms, ie. Ruf, etc. The limit agreed upon was 155mph.

 

I've hit 160 on my digital gauge. On most Z's, the 2 gauges are about 1-2 mph off from each other; and I found that my digital was about 2-3 mph higher then the speed I was accually traveling.

 

it will only go 159 which is electronically limited

 

Because of the German manufacturers' political decision to limit top speeds on the Autobahn and thereby reducing emissions. It is over a decade old and all German car makers adhere to it except Porsche and several tuner firms, ie. Ruf, etc. The limit agreed upon was 155mph.

Good point Boomer. AMG is another exception though it is by special arrangement. The Japanese also limit to 155. The previous generation 300ZTT, Supra TT, and I believe the 3000GT VR4 were also limited to 155 (I don't believe the RX7 got up that high).
rich

 

The easiest (and safest) way to find out where the electronic speed limiter cuts in is to do a top end run on the dyno.

cj

 

The Z is infact electronically limited, I talked to the guys from TechnoSquare (ECU hackers) however, It'll take a while to get above 160....theoretically it'll get 176 but I'd say on a good day, stock, we'd probably top out at right around 170.

 

Originally posted by ares
yeah tho no "proof" is shown of higher speeds, tho we do have a photo of 156mph. lots have said theyve done higher, which leads to speculation that there is no limit.

also remember, this depends on up and down hill, wind ect. at these speeds, and if you were going down hill you might get a little extra.

question is, will the fuel cutoff, limit power, or just limit acceleration? perhaps it cant accel past 156, but if your going down hill, that same power might take you a bit faster unless it starts doing engine braking, which they should be hesitant to have a car do at such speeds.
Does that mean that if the wind is 100mph you will do 260mph? No, wait, if I am going 30 and wind is 30 I am doing 60, right? What kind of world do you live in? I wish I was there. Imagine all the speeding tickets I would get .

 

i have done 171 in my z. this is with the TS flash which moves the limiter to 240 or something silly. the gearing limit on my car is just over 200mph.

at 171, the pedal still had room to go. i decided that was enough to be happy with

m

 

Damn skidazzle. you crazy ****. I hope your tires were rated for that...

I'm bringing this post back to life after my little top speed run just a few minutes ago. Absolutely bone stock base model with aero package. Temperature was 74 degrees, humidity was high at 83%, with a 9 mph CROSSWIND.

I shifted to 6th a little early, somewhere around 140. The acceleration from 140-150 was actually slower than 150-159. After I hit 150 I was gaining around a MPH every second right until I hit 159 and it just wouldn't go any faster. I kept it floored for about 45 seconds. The reason my experience might be helpful to this old discussion, is because I also went up and down a hill while it was pegged. It stayed pegged at 159 up the hill, and also down the hill. That leads me to concur with the majority that the Z is electronically limited, not drag limited. If it were drag limited, I would have either lost some speed going up or gained some going down, but neither happened.

Either way, the only thing that really matters is that the Z is one bad@$$ car. There is no debating this.

 

Got to a quiet spot of autobahn (road with no speed limit, in Germany). The autobahn was unrestricted, good weather, good visibility of course) and took the Z up to an indicated 157 mph (confirmed as being an actual 152 mph by GPS).

For your information, the digital speedo reads slightly lower than the analogue speedo. Both of these displays are controlled via the ECU. All cars overread, some more than others; it's so that you are not falsely prosecuted for speeding. Also, the ECU can work out your real speed (try pressing average speed when driving at a constant speed for 5 minutes; the 'average speed' readout corresponds exactly to GPS confirmed speed).

The car did not feel as it was being limited. Road conditions meant I needed to slow down. I believe that unrestricted examples can top 160 actual miles an hour.

There is a limitier (electronic) fitted, though I haven't reached it. Those who have say that the revs don't cut out; you just can't accelerate more.

In no way do I condone speeding; this was done on a road with no speed limits in Germany.