Miles75

Howdy all! This is my first post here, however, I've been lurking for some time.

I recently bought a beautiful black 2008 GP GXP used from a dealer in Austin TX. It was a decent compromise over the G8GT that I wanted, and it was a HUGE upgrade from the 99 Regal GS I was coming out of. The only thing I've done to it is put a K&N panel filter in it, and replace the tires with BFG G-Force KDW's (235/50's out back, stock size up front). I absolutely love this car.

I have understood from all I've read, that these cars have a factory speed limiter that shuts them off at 138. Well.....that's not true on mine. Mine apparently does NOT have a speed shut off of any sort, yet the RPM's are still limited to the factory 6K. The disabled traction control still kicks in with the slightest turn of the steering wheel. This has led me to believe that mine still has the factory programming, all except for the speed limiter.

I have a video of the speedometer in this car, accelerating from 80 to 148 mph in 30 seconds flat (Garmin GPS confirmed speed). I used a stop watch multiple times, while watching the video to verify the 30 seconds timeframe. It seems to pull at the exact same rate of speed constantly, which is much different from any other car I've ever owned. Today, I hit 150 in it for the first time in my life in a vehicle with 4 doors. Amazing for a FWD grocery getter.

So is this normal for a basically stock GP GXP?

TheMonteMan

welcome to the forum. i thought the speed was governed to 154? i could be wrong though. ive seen videos of them doing 154. ive had mine to the 140 mark.

Miles75

I thought you had to have a tune to have the 138 speed limiter removed. Maybe I was wrong?

monte_with_a_LS4

iTrader: (4)

do you have the video? and also welcome

94ss06gxp

iTrader: (5)

welcome . and lets see some pics and videos

Miles75

Thank you for the welcome! The only other modification I have done is remove the front license plate holder. I think it looks much better without it, and I rarely ever get harassed by the locals for it. A friend that's an automotive painter, painted me some "plugs" as he calls them that pop into the factory rivet holes, and the heads sit perfectly flush with the surface of the front fascia.

Here's a few cell phone pics, and the vids as well.





I have still been learning how to master the Tap-Shift. In this vid, if you watch the tach, you can see where I drop it back to 2nd at 80, bounce it off the rev limiter for a sec as I shift to 3rd @ 100 a little late, then hold it in 3rd through the rest of the range. You can also see the tach drop way down as I for whatever reason, "tapped" it into 4th as I hit 148.



This one is from today where I hit 150. BTW, this was done on a newly opened section of tollway, that has light traffic, concrete barricades on both sides, 3 lanes wide and only one clearly visible entrance for a few failry straight miles. Yes, I understand the risks of driving at that speed, and it is NOT something I will make a habit of.

jderou_GXP

Love that color!
If there were a black and red one to choose from a dealership, I would have no idea what to do.

Miles75

Thanks man! Here's a few pics of what I did with the removal of the front license plate. I think it looks MUCH better than just leaving the holes:

texasGXP08

I bought my 08 GXP brand new a 2 years ago and did 153mph in it with the factory tune and no mods. It probably would have gone faster, but I had to let off due to... not traffic.

Sittingmongoose

iTrader: (1)

Mine didnt have a speed limiter either, i hit about 163 downhill before and it wasnt limited. Maybe thats a change in the new pcm? Cause i believe they changed the pcm one of the years. Probally the same year they changed the bolt pattern on the cam and the tb plug.

AlabamaGuy

iTrader: (5)

First off, welcome aboard!
Glad to have a new Southern member.

Also, very nice GXP. That's way faster than I've had the SS!

CenTexSS

iTrader: (2)

Welcome, you're not far from where I bought my Impala - Burleson, Texas. I bought mine from Lynn Smith Chevy - great folks out there.

CenTexSS

iTrader: (2)

Nice vids, but I wouldn't advice holding 3rd gear for that long. That's a recipe for bent valves.

And it looks like North Texas Tollway, very close to 380 LOL

Gorske

I have an 09 Impala and on my stock tune mine was set to 165mph from the factory. I thought my buddy who was doing my tune was pulling my leg and then he showed me on his laptop screen. I just left it there cause thats damn fast enough for me.

Miles75

Are you saying that these LS motors cannot handle high RPM for very long....as in 30-45 second durations? That's the first time I've ever heard that.

AlabamaGuy

iTrader: (5)

We do have a very tall final gear for an LS engine. I haven't heard that either, though. Wouldn't something in the bottom end, or the timing chain have to let go?

CenTexSS

iTrader: (2)

Mixerda bent eight valves in 3rd gear @ 150ish mph

AlabamaGuy

iTrader: (5)

What physically caused it, though.

bigalnash

damn your one crazy son of a bitch what kind of tires are those? dont reconize the tread pattern

rottonj

iTrader: (4)

I was told by a mechanic at the dealership I bought the car from the factory speed limiter on mine, same as your 2008 is 163mph.He seems to know these cars. I doubt I'll get there but good luck. I have seen 145 plus, thats good enough for me.