[TommyBwell]

Not to hijack this but normally when guys are talking about what their speedo says you can subtract 5-10% due to optimistic speedos but I checked my SS against one of the signs that reads your speed and at 60 it was dead on.

 

[Treytaw]

Not my driving, but its our speedo

That is mine lol...Picture was of 162-163 but did get 164 out of it before hitting the rpm limit

 

[stvmoe75]

That is mine lol...Picture was of 162-163 but did get 164 out of it before hitting the rpm limit

And what exactly is the RPM limit? Do we know or is hit rather hard to read at 160+ ??
(And what's with the TPM light being on?)

 

[R1Budha]

Not to hijack this but normally when guys are talking about what their speedo says you can subtract 5-10% due to optimistic speedos but I checked my SS against one of the signs that reads your speed and at 60 it was dead on.

electronic speedos are set so the math formula is most precise at highway speeds so this should be no surprise.

as you go faster smaller discrepancies exaggerate. so a 5 mm larger tire diameter (depending on tire make/model/treadwear) will make a larger and larger difference.

 

[jgisonfire]

I thought the Motor Trend article was talking about top speed if you could use 6th gear to go fast. I know there is a math formula that will tell us the top speed we could reach with RPM - Gear - Rear End Ratio - Tire Size, but I was told there would be no math so I can't tell you what that would be!

 

[Speartech]

And what exactly is the RPM limit? Do we know or is hit rather hard to read at 160+ ??
(And what's with the TPM light being on?)

The rev limiter is set to 6500 RPM in the upper gears on the 2014 (6600 in 1st and 2nd gear).

 

[Jstue]

This has been dicussed somwhere on here before, just gotta do some digging. Without factoring in aero and the massive power it would require to push even near that speed.

Automatic transmissions (6L80E)

3.27 gears:
Top speed in X gear:
1st: 40 mph
2nd: 68 mph
3rd: 106 mph
4th: 140 mph
5th: 190 mph
6th: 242 mph

RPM at XX mph in 6th gear:
60 mph: 1525 rpm
70 mph: 1800 rpm
80 mph: 2050 rpm


3.45 gears:
Top speed in X gear:
1st: 38 mph
2nd: 65 mph
3rd: 100 mph
4th: 133 mph
5th: 180 mph
6th: 230 mph

RPM at XX mph in 6th gear:
60 mph: 1625 rpm
70 mph: 1900 rpm
80 mph: 2125 rpm

3.73 gears:
Top speed in X gear:
1st: 35 mph
2nd: 60 mph
3rd: 90 mph
4th: 123 mph
5th: 166 mph
6th: 212 mph

RPM at XX mph in 6th gear:
60 mph: 1750 rpm
70 mph: 2033 rpm
80 mph: 2333 rpm

4.10 gears:
Top speed in X gear:
1st: 32 mph
2nd: 55 mph
3rd: 84 mph
4th: 112 mph
5th: 151 mph
6th: 193 mph

 

[15SuperSport]

I thought the Motor Trend article was talking about top speed if you could use 6th gear to go fast. I know there is a math formula that will tell us the top speed we could reach with RPM - Gear - Rear End Ratio - Tire Size, but I was told there would be no math so I can't tell you what that would be!

This is an interesting point. The '14 top speed is at WOT in fifth gear with sixth gear being locked out. That being said, is there a sixth gear lockout on the '15 manual? It could probably be done, in similar fashion to the skip shift. The manual is also geared differently than the auto, as is the rear end gear. Perhaps they "catch up" with each other ratio wise when the auto winds out fifth and the manual winds out sixth? The gear ratios are available if someone with better math skills feels like working the numbers.
It may just take someone with a 6M winding out fifth gear, and having the huevos to bang it in to sixth and keep 'er mashed...

 

[Jstue]

This is an interesting point. The '14 top speed is at WOT in fifth gear with sixth gear being locked out. That being said, is there a sixth gear lockout on the '15 manual? It could probably be done, in similar fashion to the skip shift. The manual is also geared differently than the auto, as is the rear end gear. Perhaps they "catch up" with each other ratio wise when the auto winds out fifth and the manual winds out sixth? The gear ratios are available if someone with better math skills feels like working the numbers.
It may just take someone with a 6M winding out fifth gear, and having the huevos to bang it in to sixth and keep 'er mashed...

Manual transmissions (LS3/TR6060)

3.45 gears:
Top speed in X gear:
1st: 51 mph
2nd: 74 mph
3rd: 107 mph
4th: 153 mph
5th: 182 mph
6th: 269 mph

RPM at XX mph in 6th gear:
60 mph: 1380 rpm
70 mph: 1610 rpm
80 mph: 1850 rpm

3.73 gears:
Top speed in X gear:
1st: 47 mph
2nd: 68 mph
3rd: 99 mph
4th: 142 mph
5th: 169 mph
6th: 249 mph

RPM at XX mph in 6th gear:
60 mph: 1500 rpm
70 mph: 1750 rpm
80 mph: 2000 rpm

4.10 gears:
Top speed in X gear:
1st: 43 mph
2nd: 62 mph
3rd: 90 mph
4th: 129 mph
5th: 154 mph
6th: 226 mph

RPM at XX mph in 6th gear:
60 mph: 1650 rpm
70 mph: 1925 rpm
80 mph: 2200 rpm

4.33 gears:
Top speed in X gear:
1st: 41 mph
2nd: 59 mph
3rd: 85 mph
4th: 122 mph
5th: 145 mph
6th: 214 mph

RPM at XX mph in 6th gear:
60 mph: 1733 rpm
70 mph: 2025 rpm
80 mph: 2325 rpm

 

[15SuperSport]

Manual transmissions (LS3/TR6060)

Thanks Jstue. I know the 6M SS 3.70 is probably close to the 3.73 listed, but not sure what the RPM is in fifth showing 159 on the 3.73's. If that is our redline listed, then with a sixth gear lockout the 6M is very similar to the 6A.
I'm sure someone will find out sooner or later, on a closed course with a professional driver of course...

 

[chinamonty]

Is the SS speedo supposed to be accurate or is it supposd to read ~3% fast?

The reason I ask is that GTO speedo is designed to read about 3% fast:

On the 04-06 GTO if you push the mode or set button while starting, the dash goes into diagnostic mode where a tiny display shows the *real speed*.
The real speed is about 3% lower than the speed indicated by the speedo. using GPS and milemarkers/time to determine speed also indicates speedo reads a bit fast. Evidently this is by design - I asked the dealership to correct the speedo to indicate the real speed not 3% fast, and their response was "operating as designed".

The regulations around speedometers allow them to read up to 10% high but are not allowed to read low " The speed indicated shall not be less than the true speed of the vehicle." they can can different speedos for different models ie if you had a four cyl and a v8 in the same bodies you don't need a speedo that reads 180mph. They must show over the maximum speed of the fastest variant of the vehicle (in this case Holden speedos go up to what an HSV variant requires). They can be accurately calibrated when being assembled (ie for police) but this is not included in the price that GM pays for them. I don't think they can be re-calibrated after assembly.
The speed limiting of vehicles is often done to the capability of the tyre. ie if the tyres are rated at 160mph then the speed limiter will match that.

Here is a link to the Australian standard ADR18/03 which is based on
UNECE REGULATION NO 39/00
http://rvcs-prodweb.dot.gov.au/files/ADR 1803.pdf

 

[Pinetree]

I took GM/Chevy/Holden's word for it that the 2014 SS is speed limited to 159 mph. At least that's the message that came up on the HUD on the closed course I was using to test.

 

[chinamonty]

if the tyre are rated to 160mph then that would explain a speed limiting at 159mph.

 

[bmcassagne]

This has been dicussed somwhere on here before, just gotta do some digging. Without factoring in aero and the massive power it would require to push even near that speed.

Automatic transmissions (6L80E)

3.45 gears:
Top speed in X gear:
1st: 38 mph
2nd: 65 mph
3rd: 100 mph
4th: 133 mph
5th: 180 mph
6th: 230 mph

RPM at XX mph in 6th gear:
60 mph: 1625 rpm
70 mph: 1900 rpm
80 mph: 2125 rpm

Seems like everyone is saying they run out of gear around 160-165 but I don't remember seeing an exact rpm number. I'm looking at these gear ratios and I know for a fact in 5th gear at 90 mph I'm at 3250 rpm. That puts my redline at 6500 rpm (approx) at 180mph. I believe the Livernois tune raises redline to 6700. I know my speed was climbing at 155 mph just about as strong as it was at 140 mph. I feel like 170 mph with my tune and Roto Fab would be easy to achieve.

... Oh ya, and I checked my speed with GPS and it was almost dead on at 90 mph.

 

[RNM]

Just wondering if any of the M/T guys have a top speed above 165 posted yet? I don't have a stretch of road long and flat enough near me to feel comfortable finding out for myself how doable this is.

 

[Heron14]

This is all 20mph beyond my comfort zone. My personal speed limiter, when my swamp-nuts start swamping, are set at 140mph. My basic trill are 0 to 50 and 50 to 100, in a brief moment and 0.8G's when opportunity calls.

However, two questions:
1. When and why is 6th locked out in the '14?
2. what am I looking at in the screen to the left of the speedo? Doesn't look familiar.

 

[SLA]

2. what am I looking at in the screen to the left of the speedo? Doesn't look familiar.

Trip odometer. Play with the buttons on the left stalk and you'll find it.

 

[USAF RETIRED]

In an early road test by Road and Track (I think), they listed a GM sourced aerodynamic top speed of 178mph and a computer limit of 160.

 

[Heron14]

This is an interesting point. The '14 top speed is at WOT in fifth gear with sixth gear being locked out. That being said, is there a sixth gear lockout on the '15 manual?

.....................

What is that about?

 

[RNM]

That looks like the "trip" display to me.