Update to my first review...Not impressed with my choice of powerplant

[Joe_K]

The high end silverados and sierras come with 20 inch wheels. So would downgrading to 18 inch actually make a better ride?

 

YES!! But giant wheels are expected today due to the "bling" factor. If I would've bought a fully loaded LTZ versus my LT, I would've wanted the 18 inch wheels. I found this out first hand with my Ram, I swapped my 20's out with some 17's that come on the TRX4 edition, and the difference was DEFINITELY noticeable in both ride quality and the butt dyno.

 

The concept that I'm mentioning has nothing to do with a change in tire circumference. A change in circumference will change your effective gear ratio and how the torque gets to the ground.

 

Discussing the moment of inertia only cares about where the weight is relative to the center of rotation. Yes, if you switch GM wheels from a 18", to a 20", to a 22", the overall circumference doesn't change so your gearing doesn't change. But the circumference of the wheel itself is increasing while the amount of rubber is reducing, ie, the ratio of wheel to tire is increasing and you have more metal further from the center of rotation. And when I mention weight, I don't mean weight effecting your outright acceleration, ie, throwing the equivalent weight in the bed of the truck and expecting a change in the acceleration.

 

I'm talking merely the mass in the drivetrain that is being spun. To decrease the time it takes to spin up any object, you want to spin up the least mass possible, and you want the mass as close to the center of the axis as possible to minimize the moment arm to turn it, ie, less energy being consumed to accelerate. This is for the same reason that we're going to lightweight crankshafts, carbon fibre driveshafts, lightweight brake rotors, forged aluminum wheels. Spinning up any extra mass will consume far more energy than just throwing the weight in the bed of the truck.

 

As shown in the car and driver article posted earlier, this is very measurable in real world testing if you maintain the overall circumference of the wheel/tire combo. While it wasn't a significant change due to the overall size of the wheels being used, a person has to remember that the wheels on our trucks are MUCH heavier to be able to support the GVWR, thus it makes more of a difference.

 

The moral of the story is that if you want to cheat on the dyno, throw some 17's or 18's on your vehicle before you hit the rollers. This change will show up as a dyno is directly measuring the change in inertia of your drivetrain.

 

Smart man here.

[Jon A]

Guys, I'm having a tough time finding a 6.2 4x4 in my area right now. I hope to be able to test one really soon.

 

Where are you located? Somebody here may be able to point you in the right direction with more details. Here in Everett, WA I just got an email from a dealer today saying he had a 6.2 High Country in stock he wanted me to come and test drive (he didn't know I already ordered a Denali from another dealer). They're out there.

[mzodarg]

2 high country 6.2's sitting in Lawton, Oklahoma dealership.

[crushNchowda]

Man all this continued discussion on the guys wheels!! It's not going to make as big a difference as people make it out. Mine has 20"s and will light the tires up all over the place- it is plenty QUICK for me. Notice I didn't say fast? That's cuz it isn't going to ever be fast unless I wanna dump a ton of money into it- because its a TRUCK! The 6.2 isn't going to be "fast" either- my definition being sub 13.5 1/4 mile time minimum. You want something fast you're in the wrong vehicle.

 

On the other hand my buddy has a 5.3 sierra he feels is a lemon and is waiting for a Denali 5.3 to come inherent ordered by going through the gm buy back program. His truck does feel sluggish. Maybe there is something wrong w/ your truck?

 

But if there isn't you can do the mods I mentned for less than the price of the 6.2 and have nearly the same power and will probably be "faster" due to the superior tranny tune.

[mzodarg]

Man all this continued discussion on the guys wheels!! It's not going to make as big a difference as people make it out. Mine has 20"s and will light the tires up all over the place- it is plenty QUICK for me. Notice I didn't say fast? That's cuz it isn't going to ever be fast unless I wanna dump a ton of money into it- because its a TRUCK! The 6.2 isn't going to be "fast" either- my definition being sub 13.5 1/4 mile time minimum. You want something fast you're in the wrong vehicle.

 

On the other hand my buddy has a 5.3 sierra he feels is a lemon and is waiting for a Denali 5.3 to come inherent ordered by going through the gm buy back program. His truck does feel sluggish. Maybe there is something wrong w/ your truck?

 

But if there isn't you can do the mods I mentned for less than the price of the 6.2 and have nearly the same power and will probably be "faster" due to the superior tranny tune.

Mine will light up on demand! Don't do it often, 22" tires are expensive.

[Dj0nes]

I test drove the 5.3 today and it did seem a lil gutless.. I'm very interested in a tune but worried it will void any warranty once installed.. I don't tow much anymore I come from a 2002 24v Cummins with twice the hp as this truck lol. To say the least it was a different experience but its the better way to go since i'll just be driving it. All this 21 mpg talk is sounding nice. The truck had the 22'' wheels on it to.. may have been a good reason it was a lil slower. Not much low end torque in these. But its a beautiful truck.

[voltedge]

Fellas, I'm in Atlanta and I have found a few Denali 6.2's showing on the locator, so maybe I'll have some luck tomorrow or next week on testing one. I'm glad the last poster feels like I do about the seat of the pants power feeling. I can tell ya this about lighting up my tires...will not do it unless you power brake or are pulling out on an off kilter grade or of course wet pavement. I thought the aggressive A/T Bridgestones may have had something to do with this. As for the I'm in the wrong vehicle for a fast ride, I guess so , but after owning a Syclone for a few years and then I had a 97' Ext Cab 1500 Vortec 5.7 that was modded to the kilt except a supercharger, I know a truck can get up and go. Again, my Ram even felt pretty stout . I hope the dealership finds out if there are any other issues that could be affecting the truck. Guys, I'm just disappointed that I have a truck that is rated to tow 9,500lbs and it feels weak with the lawn mower behind it and is slow to get out of it's own way when merging with traffic. Thanks for everyone's points of view! I can't wait to put the 6.2 truck to the butt-dyno test.

[GemOutdoor]

Interesting conversations but i'm happy with my 5.3 with 3:42 and 20" wheels. Feels like a rocket to me and the couple people I have given real a ride to we're impressed.

[Aaron1085]

Interesting conversations but i'm happy with my 5.3 with 3:42 and 20" wheels......

Same. I'm only at 875miles and averaging 14.6mpg here in New England. Ran a tank of 87 and a tank of 93 octane. I drive a lot more conservative in this thing compared to my Old car, but still cruise at 80-83 on highway. Anticipating mpg may increase a bit when more miles are put on the truck?

 

I haven't even really "pinned" it yet, want to treat her right as she is my first NEW vehicle.

[redwngr]

I test drove the 5.3 today and it did seem a lil gutless.. I'm very interested in a tune but worried it will void any warranty once installed.. I don't tow much anymore I come from a 2002 24v Cummins with twice the hp as this truck lol. To say the least it was a different experience but its the better way to go since i'll just be driving it. All this 21 mpg talk is sounding nice. The truck had the 22'' wheels on it to.. may have been a good reason it was a lil slower. Not much low end torque in these. But its a beautiful truck.

After the torque of a diesel, ALL the gassers are going to seem doggy, especially in on ramp and pull-out-to-pass situations.

[Dj0nes]

Yeah I'll get use to it. Just drove the truck home about a hour ago. I love it. Spend my whole day at the dealer but worth it.

[L-G]

My 5.3 with 3.42 gears will light up my slightly larger more aggressive tires on any surface. Truck seems to have plenty of get up and go. But I do have about 2000 miles on my truck now. I can drive conservtivly and get 18.5-19 mpg on a tank. The strange thing is the truck seems to have gotten a bump in power over the last 500 miles or so.

[crushNchowda]

Same. I'm only at 875miles and averaging 14.6mpg here in New England. Ran a tank of 87 and a tank of 93 octane. I drive a lot more conservative in this thing compared to my Old car, but still cruise at 80-83 on highway. Anticipating mpg may increase a bit when more miles are put on the truck?

I haven't even really "pinned" it yet, want to treat her right as she is my first NEW vehicle.

I'm in eastern MA & travel all through New England for work, I run 93 octane (no tune) and my mpg has also been suffering. I drive about 70/30 hwy/city & have 6,500 miles on the truck. I actually think its the winter gas and me idling it when warming up in the cold mornings from time to time. My trucks well broken in by now already had first oil change. I was getting about 2mpg better average at least when new in the warmer months.

 

And in regards to the power- again I think it is plenty, and I'm coming from a string of muscle cars, the last having gone 12.7 in the 1/4

[Aaron1085]

Hmmm...maybe it's the idling and "winter gas" which I still find mystifying. Guess I'll see how it goes towards spring/summer and more break in mileage.

[GemOutdoor]

Now mileage is another story... My 2006 crew got avg 15.7 over 300,000 mi and new one with 4,300 mi is starting out at 16.4 with all the 6 speed and 4 cyl stuff. Kinda expected more and 99% of the time it's pretty much babied.