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Discussion Starter #1
Did anybody notice the top end speeds that were listed in the Car and Driver review? 109 mph in fourth at 6500 rpm, 109 in fifth at 4450 rpm, and 109 in sixth at 3300[/color] rpm. If the speed limiter was taken off, the top end would be pretty impressive. To be doing 109 mph at only 3300 rpm would indicate a lot of mph's could still be pulled out.
 

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Re: (estimated) top speed

Probably true, but I wouldn't want to be going much faster than that in a 5000 lb vehicle unless I had a REALLY long, straight, freshly paved road ;)
 

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Re: (estimated) top speed

Say to Las Vegas at 1 in the morning on a weekday. ;D
 

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Re: (estimated) top speed

Not sure how much more you would get. A lot of drag at that speed with a 5000 lb vehicle with only that much HP.[/color]
 

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Discussion Starter #5
Re: (estimated) top speed

Thats why I bought the subject up. The Acadia has a really low (apparently) drag coefficient at .36. If you look at the difference in rpm's, that should translate into a lot more speed. Of course all this is a mote point, until the computer chip is released that gets rid of the speed limiter. What we need is a good physics prof that can figure out the math while we are waiting for the chip. Not that I want to actually find out ;D
 

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Re: (estimated) top speed

Yeah, I couldn't believe it shut down when I hit 109..... the nerve of those engineers....of course my '02 Suburban used to shut off at 100....I guess I picked up a few mph
 

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Re: (estimated) top speed

Just for kicks and giggles, I decided to figure up what the top speed would be with no governor. I used these figures, taken from Autoblog:

Gear Ratio :)1)

First: 4.48
Second: 2.87
Third: 1.80
Fourth: 1.47
Fifth: 1.0
Sixth: 0.742
Reverse: 2.88
Final drive ratio: 3.16 (FWD / AWD) 2.73 (FWD) I used the 3.16 ratio for the calculations

Wheel size and type:
18 x 7.5-in; cast aluminum (std)
19 x 8-in; cast aluminum (opt)

Tire size and type:
P255/65R18 ALS blackwall (std) Tire diameter = 31.05 inches
P255/60R19 AL3 blackwall (opt) Tire diameter = 31.04 inches

It doesn't matter which tire size you use since there is only a 0.01 inch difference in total diameter, not enough to affect the results

Source: http://www.autoblog.com/2006/07/12/2007-gmc-acadia-revealed/


Now for the fun part. I used this online gear ratio calculator: http://www.xse.com/leres/ss/calculator.html
I verified the results against another two others as well. All MPH figures are rounded to the nearest whole number.

1st gear @ 6500 RPM - 42 MPH
2nd gear @ 6500 RPM - 66 MPH
3rd gear @ 6500 RPM - 106 MPH
4th gear @ 6500 RPM - 129 MPH
5th gear @ 6500 RPM - 190 MPH
6th gear @ 6500 RPM - 256 MPH

These results do not exactly jive with sandman's figures from Car and Driver. Anyone have any idea why? I am guessing that one would arrive at the figures from C&D after figuring in inherent loss due to it being an automatic transmission, but this is one area of cars that I do not know as much about as I'd like. Feel free to double check my figures, and if anyone knows something I don't that would explain these discrepancies, please enlighten me. ;D
 

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Re: (estimated) top speed

I'm just guessing here, but I'd assume those numbers would be in a vacuum. In the real world, you have friction, wind resistance, etc. to contend with. For my birthday last year, my wife bought me a weekend "driving class/racing pass" to Virginia International Raceway for my G35 coupe. One of the stipulations is you have to have your windows down (in case you wreck, easier extraction/less glass was what they told us). If you haven't tried it, 130MPH with you windows down is EXTREMELY violent! I had no concept of how much effect wind resistance had at those speeds until that weekend...
 

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Discussion Starter #9
Re: (estimated) top speed

Those numbers are pretty close. Thanks for all the work. One possibility for the difference is that Scotty (on the old forum) noted that the final drive ratio does slightly change. I quote, "One added benefit (although quite minor) is by using that 19 inch tire that is smaller, it actually changes the gear ratio from 3.16 to 3.28." That might make up the difference? Anyway, I guess we will just have to wait until someone comes out with the computer chip that defeats the limiter (and hope that anyone crazy enough to try, can still remember how to use their computer).
 

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Speed Limiter

Anyone find the speed limiter?  The "H" Good Years are rated for 130 mph.  I have no intention of going that fast in such a large vehicle and would bet the limiter is much lower.  I can say the limiter is North of 102 mph.  I'm betting 107.  Maybe I'll look tomorrow if the wind stays down.
 

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Re: Speed Limiter

I read on another site that the speed was limited to 103, but I can't find the relevant thread now.

Kelly
 

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Re: Speed Limiter

I think it was 109.
 

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Re: Speed Limiter

I believe the top speed is governed by the software in the transmission computer, and without the limit, the top end would be scary fast in 6th gear. There was a complete calculation of gear and speed on a thread on another board, but I can't remember where.
 

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Re: (estimated) top speed

For those wondering about the speed limiter question, here is the origional post.
 

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Discussion Starter #15
Re: Speed Limiter

check the (estimated) top speed post above.
 

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I'm from Canada and just for s's and g's I decided to poke around to see if anyone maxed out an Acadia. In Canada, speed limits on the highway are a measly 100 KPH ( 60 MPH )

So to get around this and have some fun, I decided to go to a quiet back road that was recently re-paved, and lay the hammer down so to speak. What I felt had amazed me.

I have a 2011 GMC Acadia SLT 2 with chrome rim package. Its got 14000 miles driven ( not alot yet ) and its never really been put through any tough situations. I managed to get the speed limiter off with a simple resetting of some computer chips.

With nobody in my way, I saw the speed go up past 100 kph, to 120, then onwards to 150, even to 160, and I figured, " Hey, it probably won't go any quicker than that. I was wrong. I hit 202 KPH at about 6000 RPM in 6th gear before I even worried about braking. For the American fans here, the conversion is 202 KPH = 125.516981.

Anybody want to go faster than that, please do so and let me know what the maximum is?!
 

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wajmat said:
I'm from Canada and just for s's and g's I decided to poke around to see if anyone maxed out an Acadia. In Canada, speed limits on the highway are a measly 100 KPH ( 60 MPH )

So to get around this and have some fun, I decided to go to a quiet back road that was recently re-paved, and lay the hammer down so to speak. What I felt had amazed me.

I have a 2011 GMC Acadia SLT 2 with chrome rim package. Its got 14000 miles driven ( not alot yet ) and its never really been put through any tough situations. I managed to get the speed limiter off with a simple resetting of some computer chips.

With nobody in my way, I saw the speed go up past 100 kph, to 120, then onwards to 150, even to 160, and I figured, " Hey, it probably won't go any quicker than that. I was wrong. I hit 202 KPH at about 6000 RPM in 6th gear before I even worried about braking. For the American fans here, the conversion is 202 KPH = 125.516981.

Anybody want to go faster than that, please do so and let me know what the maximum is?!
I can't see you hitting 6,000 RPM in 6th gear, maybe you meant to say 4th gear? As for US models the top speed limiter is around 110MPH, I hit that on a long empty back road here in FL and it comes up with a message on the DIC something like top speed limited. ( I can't remember as it was last year I did it ) I would say you could have someone remove ( reprogram ) the limiter from the ECM but who needs to go faster then that in a Acadia? :shrug:
 

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MA Acadia said:
I can't see you hitting 6,000 RPM in 6th gear, maybe you meant to say 4th gear? As for US models the top speed limiter is around 110MPH, I hit that on a long empty back road here in FL and it comes up with a message on the DIC something like top speed limited. ( I can't remember as it was last year I did it ) I would say you could have someone remove ( reprogram ) the limiter from the ECM but who needs to go faster then that in a Acadia? :shrug:
Wow - wouldn't 105 be sufficient ???
 
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