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Discussion Starter · #1 ·
There has been a lot of posting about the lack of acceleration of the Acadia as well as complaints about the 6 speed transmission. I spent the afternoon looking into the specs of the Acadia, and also several other comparable vehicles mainly to see how they stacked up for HP/Torque, weight, and MPG.

I'm going to paste a screenshot of a MS Word document (document attached for download) I wrote today. My goal was to compare Acadia data vs. other 2009 CUVs. I went to Edmunds.com and filtered the vehicles as follows:
1) Under $50K MSRP (this eliminated the Audi Q7 and some of the BMW/Mercedes models)
2) Seven passenger seating (this eliminated some of the 4 cylinder and V6 models with 5 passenger seating)

I ended up with 20 other models to compare (some were the same model with different motor options).

The following data fields were captured for comparison:
Price
Weight
Engine type/size and HP @ RPM and Torque @ RPM
MPG
Number of transmission speeds
Seating capacity
Towing capacity

Screenshot:


The data does not take into account numerous variables that will disqualify a vehicle based on individual needs or preferences, such as appearance/style, no rear AC vents, third row too small, certain option not available, etc.

While I'm at it, I'm going to paste in a reply I made in another thread about engine torque and why this is actually more important than HP alone for a heavy vehicle:
A smaller engine can make a whole bunch of HP- as I've also observed here, the 3.6L DI motor makes more HP than my 5.7L 1995 Trans Am did stock. The DI motor is rated at 288 HP @6300 RPM and 270 ft-pounds of torque @3400 RPM.
GM 2009 Acadia specs

Torque is what moves a vehicle. HP is torque over time. A smaller displacement engine will not make as much torque as a larger one. What is the redline on the Lambda motor- 6500~7,000 RPM? Our tach is not marked for this and I couldn't find this info anywhere. It makes the 288 HP well up into the RPM range. How much time does the average driver spend there or even close to there? This makes the higher HP far less relevant to a daily driver, unless perhaps your commute includes Road Atlanta or VIR :). Coupled with the six speed automatic, you're going to see more shifting to get anywhere close to best acceleration.

I also drive a heavier vehicle with less HP. It's called a 10 year old Durango that when new was rated at 245 HP. Even with like 140K on the clock, it has decent acceleration as compared to the Acadia even with less HP and larger (wider) tires. Why? The 5.9L V8, the four speed automatic trans, and the final drive ratio. The 245 HP is rated at 4000 RPM, while it makes 335 torque at 3200 RPM (statistically, this is 24% more than the Acadia). My truck also has a 3.92 final drive ratio, compared to the 3.16 of the Acadia. If the same vehicles have a 3.16 and 3.92 final drive ratios, the 3.92 will accelerate faster than the 3.16 equipped vehicle. My truck also averages 11-12 MPG vs. 19-20 for the Acadia.
Durango specification from Allpar

EDIT
MPG values for the Acadia were for the AWD version due to my error. I have corrected these to the FWD values.

EDIT 2
I'm somewhat myopic when it comes to Acadia engine & transmission issues since I don't drive ours that much and it drives so differently than what I do normally drive. The transmission programming (flash) plays a large role in the performance of the vehicle. I have created a link to transmission flash TSB info compiled thanks to info from member GeoHawk here. If you are experiencing performance or shifting issues, please look there for info you can give the dealer.
 

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Blue, you continue to amaize me with your tech stuff. Maybe us Acadia owners don't realize how good we have it over the competition with engine, torque, hp. wt.........etc. I don't want to buy the competitions so called equiv. That is really something to see what they all really have on a chart comparison. Thanks!
 

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Not that I don't agree with you, but did you factor the rear wheel tire/wheel rolling diameter difference into into your gear ratio calculation? Its effect is just as direct as the actual gear ratio. Considering that the Acadia has a relatively large tire diameter overall it might actually make that comparison even worse.
 

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Discussion Starter · #4 ·
teeter,
Thanks, I'm happy to help out with things I enjoy doing.


Gerry,
Very true... the Corvairs that drag raced in the 60's used tiny OD tires (I think on like 12" wheels) to get the RPM in the right range since the final drive was limited- most had a 3.55:1. This method in reverse (with taller tires) was a poor man's overdrive back in the day to slow down the motor at highway speeds since top (3rd or 4th) gear was 1:1. We could get away with that on the 65-69 Corvair w/o a speedometer error since the speedometer was driven off the left front wheel. :)

As for the referenced final drive for the Acadia vs. the Durango, both have stock diameter tires on them. The Durango had the optional wider 17" R/T wheels added to it with correspondingly wider tires. More unsprung weight to overcome, but also better traction.

The 3.16 to 3.92 final drive analogy was for two identically equipped vehicles, I should have spelled this out instead of saying "the same".

I did not post final drive ratios for any of the comparison vehicles. Unfortunately, to get all of that data taking into consideration the tire size differences would require more work than I want to put into it at this point. I was lucky to find all of the data in one place at Edmunds... I started w/ www.Cars.com, but by the second vehicle I looked up, they had no data for much of it.
 

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Thanks for taking the time and spending the effort to put together this chart. It's very informative.

But horsepower, torque & weight doesn't tell the entire story. What also matters is the torque curve, gearing ratio, final drive ratio, wheel size and, most importantly, the efficiency of the transmission (eg. how fast it shifts, input to output loss etc.).

I also drive a compact car with half the weight and 1/3 the horsepower. But because it has a 5 speed manual, the first gear's gear ratio is lower, the clutch has a positive engagement and I keep the revs in the power band. Hence it feels more responsive. Many times when I exited corners I felt the 3.6L V6 very slushy and slow to respond compared to the 1.9L I4 engine. This has more to do with the transmission than the engine.

Prior to the Lambda, I had driven 5-speed manuals for almost 20 years. Going from manual transmission to automatic is an adjustment. And I attribute the slushy feel to the automatic transmission. I'm not sure if all auto trannies feel this way or if this is isolated to the Lambda vehicles.
 

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Discussion Starter · #6 ·
eelfliw said:
But horsepower, torque & weight doesn't tell the entire story. What also matters is the torque curve, gearing ratio, final drive ratio, wheel size and, most importantly, the efficiency of the transmission (eg. how fast it shifts, input to output loss etc.).

I also drive a compact car with half the weight and 1/3 the horsepower. But because it has a 5 speed manual, the first gear's gear ratio is lower, the clutch has a positive engagement and I keep the revs in the power band. Hence it feels more responsive.

Prior to the Lambda, I had driven 5-speed manuals for almost 20 years. Going from manual transmission to automatic is an adjustment...
You can say that again.

Aside from the Durango, I drive lighter compact (and one not so compact- 4" longer/wider than the Durango) cars with half (Daytona) to the same (Supra) to roughly 90% more (Trans Am) HP than the Acadia. All have manual transmissions and all but one have a Chevy or Dodge V8 in them. Honestly, it's a letdown when I need to pass a vehicle in the Acadia on a two lane road when I compare how the other ones drive. But they burn more gas and can't haul the relatives around when they visit. Actually, only one of those is a drawback. ;D

The data needed to do a comparison with the mentioned input data would really take quite a bit of doing, and I doubt it is easily available. I don't have that much time on my hands ;). I was surprised to see so much of a torque/RPM variation in the torque values for similar sized motors- I saw a lot more variation here than I expected. It may be easier to get 0-60 or standardized passing times, say 50-70 or such for each vehicle, if available, to quantify this further. I'll look into this and see if it is available.
 

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Great info Blue. Thanks for putting that together.
Sure looks to me like the Acadia is a tough competitor in this crowd.
With better that average HP and near the top in fuel economy, in a vehicle that's maybe the largest in the list.

One question. Were you looking to compare the Acadia in AWD trim or FWD?
(Looks like the curb weight of the FWD but the MPG of the AWD).
 

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Discussion Starter · #8 ·
I actually listed data for the Acadia that I didn't already know from www.Cars.com, since I thought the same fields would be standard for all vehicles. Cars.com listed the MPG for all models, so I was using the lowest of the numbers to be consistent. When I went to the next vehicle (Borrego), I found a bunch of stuff missing. I then went to Edmunds for the remaining vehicles.

I checked Edmunds just now, and it is indeed 17-24 for the SLE FWD which is what is listed otherwise. I'll correct the chart and re-post it. Good eye. :thumb:

I also did not see any type of performance data there such as 0-60 or 1/4 mile time/speed. I found data on the Motor Trend website for the 2007 Acadia, but obviously I want this data to match the years/models I already have.

UPDATE 6-5-09
Original post updated with link to transmission flash TSB thread.
 

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taskmaary said:
typically the product will arrive within 3days via either Fedex/Ups and TNT Courier Sevices.
Caught ya, :spam: er!! And, you've been duly reported to the site mods.
 

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