[SSport16]

Suprised they are not really advertising the 180 mph top speed for the SS, would be good marketing. They do it with the Vette all the time.

[motorhead]

Originally Posted by Hyper RS

Lol....Would be curious to find out what the top speed would actually be, if the 4 and the 6 were drag limited as the SS is.

We may be surprised. I bet it's faster than most would think. Why are the 4 and 6 limited? Tires?

[SuperSound]

Originally Posted by motorhead

We may be surprised. I bet it's faster than most would think. Why are the 4 and 6 limited? Tires?

Yep, no Z rated ones. Wonder if the 1LE V6 will have it removed.

[JaxChris]

Where are you seeing 180mph? For 6th gear in the A8, the mechanical top speed is 195mph when pushed to 6500rpm. The drag limit for the estimated Cd, Frontal, Weight with Driver & fuel should be 180mph based on 20% drive loss, 25 rolling resistance, 4000 lbs w/ driver&fuel, 28 sqft of frontal & a 0.32 Cd. With these numbers it says our car makes 470 bhp, not 455. Small difference but it explains the higher rwhp figures people are seeing on the dynos.

But actual peak power stops around 5700rpm in 6th gear (overdrive gears don't work accelerate over 120mph or so), so that brings top speed down to 171.5mph. This is based on the A8's 2.73 rear end and 27.6 tire diameter with a 1:1 gear ratio in 6th with the converter locked. The person that posted the below video thinks there is a governor, but he just hit the true mechanical limit of his car and the speedo rounded 171.5 up to 172mph. You'll need to raise your effective peak power RPM in 6th gear to go any faster. I don't think anyone is going to swap a 2.73 for an even taller gear just to set a speed record in the Camaro6.

[pjz1082]

I'm not dumb enough to drive 149 mph so I guess I should do just fine with my 2 less cylinders

[gw6211]

i dunno, it just stopped at 172, like it was clicking like a mph a second and stopped. Seems like if it was struggling due to drag that it would be slower and slower to reach the top speed, not just stop.

[Drags1998]

The Convertible is the ONLY 1 to be Limited, And that is limited to just about 160MPH!!!! DON'T ask how I know!!!!

[oneredry]

Originally Posted by JaxChris

Where are you seeing 180mph?

seen it in the Sales brochure. I would believe this as there was a video done by Hennessey a 1 mile flat out with the car and achieved 170 not a problem.. However, I did see it slow down a bit when reached those speeds but I believe he ran out of room. from the looks of the tach, he had plenty to go RPM wise. when he F/I'd the car, he was clocking somewhere around the 202 mark.

[LesserO2Evils]

Originally, on the 2016, they stated it was set@175. Now Im seeing 180, but IDK if that is a 2017 specific number, or no.
I saw 176 for a nano-second, and then maintained 175 for a long ways without moving.

[wnta1ss]

It was posted that the 2016 SS had a limiter in it's ECU set to 180. This is why I'm wondering if it's also done to the 2017.

I agree that video does not look like a true drag limited speed, as it should struggle a lot more to gain the last couple of mph if it really was nearing the drag/hp balance point.

I ran a couple estimates to compare transmissions, at the power peak rpm listed:
A8=2.77 rear, using 6th gear, 5700rpm = 168.8
M6=3.73 rear, using 5th gear, 5700rpm = 169.4

These estimates used the theoretical circumference of a 275/35-20 tire and therefore it's likely that those speeds are higher than reality for a given engine rpm.

[JaxChris]

I based my numbers on 2.73 in the rear, which gave me 171.5mph, which does happen to line up with that video. After 5700rpm, HP starts to dip from what I've seen on stock dyno runs. Only way to get more speed is to increase the peak HP rpm or use an even taller gear. Other than that, it is topped out and not hitting a governor.

Boost can move peak power up the scale, but you don't want to exceed the engines operating speed without some more massaging. So if Hennessey did get 200mph, he moved peak HP to 6700rpm (201.5mph), which is past the GM recommended threshold of 6600rpm for the stock internals.

[SuperSound]

Originally Posted by wnta1ss

It was posted that the 2016 SS had a limiter in it's ECU set to 180. This is why I'm wondering if it's also done to the 2017.

I agree that video does not look like a true drag limited speed, as it should struggle a lot more to gain the last couple of mph if it really was nearing the drag/hp balance point.

I ran a couple estimates to compare transmissions, at the power peak rpm listed:
A8=2.77 rear, using 6th gear, 5700rpm = 168.8
M6=3.73 rear, using 5th gear, 5700rpm = 169.4

These estimates used the theoretical circumference of a 275/35-20 tire and therefore it's likely that those speeds are higher than reality for a given engine rpm.

5th gear in the M6 is an overdrive I believe, so wouldn't be useful.

[wnta1ss]

JaxChris, I got the 2.77 rear ratio for the A8 from a Chevy website.

SuperSound, yes 5th in the M6 is an overdrive. However, it's the gear that puts the engine at it's peak hp in the generally expected area of speed the car might reach. Using 4th (1.00:1), the 6500rpm redline would raw estimate to 143, which is obviously below the car's potential.

[toro1966]

Hey guys - not that I ever intend on going that fast, but can someone confirm for me whether or not the convertible 2SS is governed, and if so, at what speed? Thanks.