View Full Version : AWD or RWD?
I can't seem to make up my mind about whether to get AWD or RWD. FYI, I am in Southern California, so AWD is not a necessity for me.
The AWD is 200 lbs heavier, gets 1-2 MPG worse gas mileage, and has more parts to break. On the other hand, it will certainly be safer to drive, and for those times when it does rain, or decide to go to Big Bear, Yosemite, or Tahoe for skiing, it will be better to drive.
The 2WD intrigues me for an entirely different reason. Anyone who has steered their car with their foot knows what I am talking about. On top of being lighter and getting better gas mileage, there is a factor of fun with a RWD that can't be had with an AWD.
Because of the gas mileage issue, I'm considering swapping out the 4.10's for 3.73's once I get it. At freeway speeds, this would bring down the RPM's to something much more in alignment with the efficiency range of the LS2 motor on the freeway. I would anticipate a 1-1.5 mpg or so gain with the gear swap.
The way it stands right now, with 4.10's and a 30" tire, you're looking at 2250 RPM @ 70 MPH. After the swap, it would be 2050 RPM @ 70 MPH, right outside the motor's efficiency range of 1800-2000 RPM, but close enough to give you 1-1.5 MPG more. With a 2WD and 3.73's, I bet you'd get 21-22 MPG at freeway speeds, maybe more.
A gear swap with an AWD would be painful and expensive, whereas one with a 2WD would be very simple.. With a 2WD, you could also swap in something much more stout than a G80 (Auburn or Eaton LSD, Detroit, etc.) while you were in there, without worrying about messing up the characteristics of the Torsen T-3, which would be very important.
westbayou
10-04-2005, 10:10 AM
--- If you are worried about MPG, get a TB/Envoy with the 5.3L and call it a day. Buying an SS only to swap out the rearend to a 3.73 kind of defeats the purpose of the vehicle. Obviously the 4.10's are part of what it takes to get the performance numbers they were shooting for, and swapping them out would castrate your vehicle. You could save yourself like 3 grand and just debadge the 5.3L, throw on some 20's to get the SS look without the harsher ride/worse gas mileage. This has to be a first for me, someone who wants to buy a "performance vehicle" and actually make it slower..... To each their own I guess? Let alone the cost of a gear swap would more than match the 1-2 mpg savings over the next couple of years.
homertime
10-04-2005, 10:36 AM
Wouldn't this be the influential factor 2WD = CHEAPER?
If you live in SO. Cali, and the 2WD is cheaper, I don't understand where the question is
I live in NY so my answer is always the obvious one, 4wd/awd cause the 2wd isn't really worth anything in moderate to significant snowy conditions.
Then again for anyone getting a SS in the North east, why bother with an AWD when the performance tires can't give you the control you need in snow/mud
I think the AWD option on the SS is just a comfort feature with no real usefullness. You give a truck AWD/4WD you're thinking performance in the snow and mud, not on the track
I think the AWD option on the SS is just a comfort feature with no real usefullness. You give a truck AWD/4WD you're thinking performance in the snow and mud, not on the track
IMHO, your comment is potentially an over-simplification. 4 wheels have a lot more traction under any condition, whether it be dry, wet, snow, etc. I'm not close to how the torque limitations are calibrated, but there's significant possibility that the AWD variant has better 0-60 in the dry.
It really depends on what the "weak link" is in the physical system. A 400hp TB in 2WD trim will unquestionably be traction-limited. If the trans and xfer case can handle the torque (and I suspect they can), the AWD vehicle may be able to deliver more tractive effort than the 2WD. Will it be enough to make up for the mass and parasitic loss differences? I'm guessing so, but it really remains to be seen.
Windy City
10-04-2005, 12:53 PM
Unless you're looking for strictly a drag racer, I would go for the AWD.
AWD will distribute the engine torque to both differentials so the worry about more parts to break would be offset by the reduced stress that would otherwise be placed on the rear differential alone.
Have you ever driven an AWD vehicle before? AWD is great for slippery roads but it even improves handling on dry roads. AWD isn't just for snow.
And of course AWD does help with slippery roads. Does it ever rain by you? I'm sure it does and having AWD will keep your rear end in check and think of the fun you'll have racing EVO's and WRX's even in the rain.
I've spent the last two years driving a Northstar V8 320 hp AWD Cadillac SRX. Control and power delivery in all conditions (dry, wet, snow) is phenominal.
Needless to say, I ordered my Black TB SS with AWD.
David
Blulytes
10-04-2005, 09:26 PM
my dad has the SRX AWD... that truck is very nice.
but yes, I agree, the handling is great in all weather conditions.
This has been a very interesting thread. I appreciate all of your input.
As of today, I am leaning toward 2WD. The reasons are as follows:
- Better fuel economy
- Less weight, nearly 200 lbs less
- Less moving parts to break
- Ease of gear change (I am 90% sure I will do this)
- Ease of locker/LSD differential change (same as above)
- Ease of exhaust upgrade (I am 100% sure I will do this)
- Ease of potential future transmission upgrade (i.e. 6L80)
There is some speculation if the 4L70E transmission is up to the task of powering a 4800 lb vehicle that puts out 400 HP. I have to admit I have my doubts. The 4L60E does not have a great history of holding up behind weight + power, which is one reason I am leaving the possibility open of a transmission upgrade to the heavy-duty 6L80 (which would be very nice gearing, BTW). The only way to leave the door open for a clean swap is to stick with 2WD.
Also, there is very little extra room under a Trailblazer. To take up that precious available space with a transfer case means there would be very little room for proper exhaust modifications, which I think the vehicle will desperately need. As it is engineered right now, it must be choked, or loud, or both. To see that ricer can at the end of the vehicle makes me kind of ill, and I have my way, it will be going. I don't see that being possible with the AWD setup.
I suspect that if I get a 2WD and swap out the gears to 3.73's, I would get 23-24 MPG at freeway speeds, or perhaps more. Now some of you might say, "Big whoop, 24 MPG!"...but an SUV with 400 HP that gets 24 MPG would be anomolous compared to what's on the road today, and I think I would like it very much (especially when it came to filling it up). I am actually considering 3.42 gears, although I would have to do some more calculations to see the benefits over costs. This might be doable as well.
For those of you scoffing at this idea, like westbayou, it is clear that you are not familiar with the LS2 motor. There is plenty of torque available down low, so there is not a desperate need to gear the vehicle like they have. If the TBSS had 32" tires (like a stock Silverado SS), then that would be another story, you might need the extra gearing off the line. But you have a tire that is 6.5% smaller on a motor that has no problem making power down low. It doesn't make a lot of sense, since you will be losing roughly 1 mpg for every 200 RPM's over 2000 RPM you run.
Here is an actual dyno graph from a GTO with an LS2:
http://www.ls1tech.com/GTO/dynoLS2gtoStock.gif
As you can see, you get almost all of your available torque at 2,000 RPM's, which could overcome almost any kind of gearing, even 3.42 if you wanted.
I some business to attend to, but I will be back later to discuss this further. :D
ScarabEpic22
10-04-2005, 11:44 PM
I think 23-24mpg is a little bit of a stretch, considering the speculated mpg are about 12 2WD-13 AWD in the city and 14-15mpg hwy. How does a gear change net you 8-10mpg? Also, as mentioned before, you are pulling most of the performance away from the vehicle with the lower gears. How will you get the 6L80 to work in an SS? Highly doubt you can just swap trannys and plug in the stock paramaters, since the stock tranny is the 4L65-E.
Dont get me wrong, do what you want with your truck, but Im not following how you can get these to work.
Also, I would say go for AWD if you decide to not do some of your planned mods because it will give you better wet and dry traction in So Cal.
I suspect that if I get a 2WD and swap out the gears to 3.73's, I would get 23-24 MPG at freeway speeds, or perhaps more.
Unless you are going down hill with the wind behind you I dont think you will ever see 20 mpg. The SSR (even though it weighs more) has 20 inch rear tires, the same engine and basically the same trans and 3:73 gears is still not rated @ 20mpg on the hwy. And imo the mpg ratings that the manufacturers issue are the one thing that are totally inacurate on the spec sheet. So in the real world the SSR is probably pulling down 15 mpg on the highway. Of course this is unconfirmed. :undecided Good luck with your goals.
The LS2 in the GTO is not pushing something shaped like a brick also. I run 3.73s in my CTS V with the LS6 and it gets around 24mpg on the highway. I just don't see the SS getting above 20mpg ever.
You may want to consider a different vehicle if gas mileage causes you to go with something that gets only 1-2 mpg (and still crappy) gas mileage.
I think the AWD adds something unique to the SS. Otherwise it might just be cheaper and more economical to buy a sports car.
I guarantee I will see 20 MPG minimum on the freeway, and perhaps 22, 23, or more once I am done. :eek:
I'll ask you all a question, and I would like you to think about it before you answer. Ready? How do you suppose is it that the 2005 Corvette is able to get 28 MPG on the highway? It has the 400 HP LS2 for a motor...how can it get mileage so much better than the SSR which has been mentioned here?
There are three reasons why the LS2 Corvette gets 28 MPG:
1) Aerodynamics
2) Weight
3) Gearing
As far as the first factor, aerodynamics, goes, nothing much can be done with the TBSS, or at least nothing significant. I will say, however, that TB/Envoy is actually pretty aerodynamic for an SUV. Compared to a Ford Explorer or Expedition, or a Chevy Suburban or Tahoe, the Trailblazer cuts a pretty nice line through the wind. So a Corvette it is not, but it is certainly not a brick on wheels, like the Suburban is.
The second factor - weight - is an area where something can be done. The 2WD version is around 4500 lbs, correct? Well, it is not the Corvette's 3200 lbs, but it is not the 5200 - 5400 lbs of the Tahoe, either. So if the Tahoe can get get 20 MPG on the freeway with a puny 4.8L motor working its little butt off, you can bet the TB SS can get 20+ with over 100 more HP at its disposal.
The last factor - gearing - is the one factor that people here are clearly uneducated on. Part of the reason the Corvette can get 28 MPG on the freeway is the RPM the vehicle is cruising at while in 6th gear (.50 ratio). Gearing for the LS1/LS2 motors is critical when it comes to gas mileage efficiency. The absolute best mileage will be had between 1800-1900 RPM. Any higher than that, and you start losing gas mileage, somewhere around 1 mpg for every 150-200 RPM over 1900 RPM.
Do the math using an RPM calculator, like this one here. (http://www.car-videos.com/tools/speedrpm.asp) Enter in 255/50-20 for tires, 4.10 for axle ratio, 3.06, 1.63, 1.00, and .70 for Gear Ratios (4L70E), and 50 RPM increments. You'll quickly see that to travel at 65 MPH in 4th gear, you need to be turning the motor at 2150 RPM - outside of the motor's efficiency range. You're losing 1.5-2 MPG at that point, and incrementally more as you increase speed and RPM.
Now plug in 3.73 for gears and see what happens...you get 1950 RPM at 65 MPH, and about 200 RPM less across all the range. I guarantee you that if you cruise at 65 MPH with those 3.73 gears you will realize 2 MPG more than you would if you cruised at 65 MPH with 4.10's. It isn't rocket science, these are simple calculations based on well known LS1/LS2 facts.
And for those who think that performance will suffer with 3.73's, I would be willing to race you when I get mine and you get yours. :D The 4.10, while a torquier gear, is also a shorter gear, which means when you are shifting, I am still in my powerband and haven't yet shifted. With a short 30" tire and a short 4.10 gear, you'll be shifting harder and more often than me. Plus, unless you have AWD, you'll have a hard time getting traction. With the 3.73's, it will definitely be easier.
Here's a question for all of you....why do you suppose the TB SS is coming out with 4.10 gears? I have my ideas, but I'd really like to hear yours.
TrailblazerSS
10-05-2005, 07:22 AM
From Car & Driver Article (http://www.caranddriver.com/article.asp?section_id=41&article_id=10002&page_number=2)
Chevrolet TrailBlazer SS
Vehicle type: front-engine, rear- or 4-wheel-drive, 5-passenger, 5-door wagon
Base price: $33,600-$39,200
Engine type: pushrod 16-valve V-8, aluminum block and heads, port fuel injection
Displacement: 364 cu in, 5967cc
Power (SAE net): 395 bhp @ 6000 rpm
Torque (SAE net): 400 lb-ft @ 4000 rpm
Transmission: 4-speed automatic
Wheelbase: 113.0 in
Length/width/height: 191.8/74.6/67.8 in
Curb weight: 4600-4700 lb
Performance ratings (mfr's est):
Zero to 60 mph: 5.4-5.5 sec
Standing 1/4-mile: 13.9-14.0 sec
Projected fuel economy:
EPA city driving: 14-15 mpg
EPA highway driving: 17-19 mpg
Don't know where the source data is from but it's about what I expect. As the owner of a LS1 with with a 4L60 I've made a gear change from 3.23 to 3.73. By your factor, my fuel economy should have gone down by 2-3 MPG. The change (in highway crusing) was less almost unnoticable, less than 0.5 MPG. Checked and verified several times.
Response to gear changes is nearly linear for RPM operating ranges, but NOT for fuel economy. Your 1 mpg for every 150-200 RPM over 1900 RPM factor is way too optimistic. By a factor of 4 to 5. If 17-19 is right you'll be fortunate to see 20 with a swap to 3.73's.
I just don't understand the logic running contrary to the point of owning a performance SUV. 2WD will suit you for what you have planned, but I don't know why you would want buy this vehicle given your priorities. :confused:
As for why GM chose the 4.10, it makes the vehicle fit in the RPM operating window at highway cruising speed.
I guarantee I will see 20 MPG minimum on the freeway, and perhaps 22, 23, or more once I am done.
"Guarantee" seems to be a pretty strong word in this situation, given the kind of real-world fuel economy that folks see with the 5.3L and 3.73 or even 3.42 gears in the regular TB and Envoy. My personal experience suggests that anything very far into the 20's will be challenging, again at real-world freeway speeds of 65-70mph.
That said, if they are able to cert a 19 Hwy for the window sticker on the 2wd, there is some possbility that you can swing 20. Again, the "reality" of a vehicle of this type (lots of fun under that long skinny pedal) and a DIC-indicated steady-state fuel economy number really have no relevance to one another. :D
As for the 6L70, don't underestimate that transmission - it's a great balance of strength and efficiency. One other thing to consider, particularly if you are on a fuel economy kick: you would be well-served to better understand the parasitic losses of the 6L80 vs. 6L70 as part of your analysis. I agree that the L80 has a better ratio spread, but it also has a fixed-displacement oil pump, higher mass, and greater parasitic losses.
I think TrailblazerSS hit it on the head when he clarified the point that rpm does not in and of itself, equate to fuel consumption. You would be best served by locating fueling maps for the LS2 application to really make a good analysis.
Either way, best of luck with your project!
westbayou
10-05-2005, 10:28 AM
Dude, knock me if you want, but you sound just like my brother when he tries to prove something. He researches the crap out of it, comes up with some good numbers that support his argument, but forgets that in real life, things don't always work out as well as they do on paper. TrailblazerSS summed it up perfectly. Sure, your argument sounds great in an IDEAL situation, but I'll be suprised if you seen that great of an increase in MPG, and I mean really, is 1-2 MPG worth all that hassle???
But back to my point, from the sounds of your priorities, why in the heck would you buy an SS just to hack it up for fuel economy? On one side you are looking to reduce the performance by changing the gear ratio to gain MPG, but on the flip side you want to do exhaust work to enhance performance? Since you are hooked on numbers in ideal situations, 2 drivers in identicle vehicles with different ratios will have 2 very different performing vehicles. Saying you would still beat a 4.10 SS with 3.73's or 3.42's assumes a lot man. A decent driver is going to have no problem launching with the 4.10's. You throw a set of 3.42's in there and you are going to be right back at the 5.3L TB performance numbers, regardless of torque.
TrailblazerSS
10-05-2005, 11:21 PM
And for those who think that performance will suffer with 3.73's, I would be willing to race you when I get mine and you get yours. :D The 4.10, while a torquier gear, is also a shorter gear, which means when you are shifting, I am still in my powerband and haven't yet shifted. With a short 30" tire and a short 4.10 gear, you'll be shifting harder and more often than me. Plus, unless you have AWD, you'll have a hard time getting traction. With the 3.73's, it will definitely be easier.
I forgot to comment on this last paragraph. At red line the 1-2 shift will be 43 MPH for the 4.10 Gear, 47 MPH for the 3.73 gear. While accelerating 0-60 in 5.5 seconds those two shift occur less than 0.2 seconds apart. Big whooop! :duh: The 2-3 shift point is 81 and 88 MPH respectively, still less than a 1/2 second difference. 3-4 is 131 and 144 MPH, now theres some difference. You are making a mountain out of a mole hill.
Aerodynamics is one of the biggest factors with gas mileage. You are essentially trying to push a brick, instead of a smooth object through the air. The USAF has done this before with the F-4 Phantom. It proved if you put enough power behind something it will move effectively. Then the F-16 came along over 26 years ago with a single engine and outpowered the F-4.
The Corvette is like an F-16 while the SS can be compared to an F-4. SS will be a very nice vehicle but gas mileage will NOT be one of its good points. My 5.3 is just pulling 2000 rpm at 75mph with its stock gears. It gets 19mpg at best cruising at 75mph.
Extra 100hp doesn't matter much when cruising at a slow 65mph. You only need around 20hp to cruise at that speed.
Lower final gearing will help gas mileage a little, but your performance will suffer greatly. It will be lucky to hit 0-60 in 7 seconds. Your engine will most likely be out of its powerband also and will not feel like it has almost 400hp. I would guess that any money you save in gas won't amount up to the money you spent to mod the vehicle. Best of luck anyway!
a990dna
10-06-2005, 01:24 AM
Interesting thread... bench racing is always fun.
I think you should buy the car first and then decide if you want to mess around trying to squeeze out 1.5 MPG.... for what percent of the time? Socal freeways are bumper to bumper pretty much all the time now. So when will you actually hit that optimum RPM?... and for how long?
I'm not opposed to a gear swap or installing aftermarket exhaust systems for marginal gains... but you'd need to make quite a few long distance trips for a reasonable ROI. Big Bear isn't that far and half the trip is mountain driving anyway... it's going to suck more gas going up that grade w/3.73s.... as I spent 20 years making that drive you're talking about.
AWD and 4.10s would be a better fit for around town and mountain driving.... but if you want a freeway cruiser then buy a 2WD and change out the gears. Personally, I wouldn't do to much to it because you may just void your warranty on a vehicle like this...
IMO, GM probably loaded the pumpkin with 4.10s for strategic reasons... 1) to achieve sub 14 sec 1/4 mile times.... 2) claim the highest towing capacity among the peer group. win win.
If GM could've done all this and achieved a 2-3 MPG advantage against the peer group by using taller gears, don't you think they would've done it?
Seems like a simple concept to me.
a990dna
10-06-2005, 04:00 AM
BTW, if you run the numbers it will take you approximately 6-7 years to recover your modification costs. It doesn't make financial sense to do this....
Example:
Net MPG Increase 1.5
Tank Gallons 20
Additional Miles per Tank 30
Average MPG 18
Gallons Saved 1.67
Cost per Gallon $3.00
Savings per Tank $5.00
Modification Costs $2,000.00
Savings per Tank $5.00
ROI (Number Tanks) 400
Fill Ups per Year 52
ROI (Number Years) 7.7 (Break even point)
Cash Investment $2,000.00
401K, IRA 6.00%
Number Years 7.7
Non Compounded Gains $922.80
Thanks again for the comments. I have to say, I am amazed at the strong feelings and sharp comments about what I considering doing to my vehicle, for what reasons, and with what data. I really appreciate the effort that some of you have put forth to knock me and my ideas, it has been interesting and very amusing. I'd like to address some of your comments.
As for why GM chose the 4.10, it makes the vehicle fit in the RPM operating window at highway cruising speed.
Uh, I don't think so. At 75 MPH the TBSS is going to be running at 2500 RPM, which is going to be pretty annoying. I bet there were more than a few arguments in the engineering department regarding this decision (I'll lay off the 'guarantee' word since some of you have such a problem with it ;) )
IMO, GM probably loaded the pumpkin with 4.10s for strategic reasons... 1) to achieve sub 14 sec 1/4 mile times.... 2) claim the highest towing capacity among the peer group. win win.
These are the most likely reasons, although gear changes don't result in changes in 1/4 miles times as much as they result in a higher trap speed with similar times. A faster 0-60 is the more likely reason, being as this spec is thrown about more often in the mainstream auto press, and the 4.10's definitely help here. And at the expense of MPG and freeway driving comfort, I might add.
Not sure this is such a win-win, unless you are buying a TBSS to race. Great, so the 4.10's got GM the specs they wanted, but at what cost? If you will be driving it daily to work, going on trips, etc., the 4.10's are a poor choice, IMO. If you never spend any time on the freeway, then it will be fine, but if you spend 50% or more time at 65 MPH or greater, the buzzing will get old very quickly. There is a reason a Corvette has a .50 6th gear.
If you think 400 HP with 3.73's and a 30" tire is going to have any problems at all with anything, like driving up a mountain, then you haven't had much experience with the '3' position, or the '2' position on your gear selector. That's what it's there for. You'll be doing the same thing with 4.10's.
Aerodynamics is one of the biggest factors with gas mileage. You are essentially trying to push a brick, instead of a smooth object through the air. The USAF has done this before with the F-4 Phantom. It proved if you put enough power behind something it will move effectively. Then the F-16 came along over 26 years ago with a single engine and outpowered the F-4.
The Corvette is like an F-16 while the SS can be compared to an F-4. SS will be a very nice vehicle but gas mileage will NOT be one of its good points. My 5.3 is just pulling 2000 rpm at 75mph with its stock gears. It gets 19mpg at best cruising at 75mph.
Extra 100hp doesn't matter much when cruising at a slow 65mph. You only need around 20hp to cruise at that speed.
Lower final gearing will help gas mileage a little, but your performance will suffer greatly. It will be lucky to hit 0-60 in 7 seconds. Your engine will most likely be out of its powerband also and will not feel like it has almost 400hp. I would guess that any money you save in gas won't amount up to the money you spent to mod the vehicle. Best of luck anyway!
I agree with you for the most part regarding mileage. But the TB/Envoy clearly cuts a better line than the Tahoe/Silverado/Avalanche, et al and those vehicles are getting 19-20 MPG, so I think 22-23 (or more) is easily attainable with the TB.
I completely disagree with you, however, on your hypothetical example. There is no way 10% higher gearing will make you 40+% slower in your 0-60 time. I'll leave the laughing smiley out, even though I know you must be kidding, right? :cool:
I forgot to comment on this last paragraph. At red line the 1-2 shift will be 43 MPH for the 4.10 Gear, 47 MPH for the 3.73 gear. While accelerating 0-60 in 5.5 seconds those two shift occur less than 0.2 seconds apart. Big whooop! :duh: The 2-3 shift point is 81 and 88 MPH respectively, still less than a 1/2 second difference. 3-4 is 131 and 144 MPH, now theres some difference. You are making a mountain out of a mole hill.
Like I said, if I do this, I'd be more than happy to race you. :D
Dude, knock me if you want, but you sound just like my brother when he tries to prove something. He researches the crap out of it, comes up with some good numbers that support his argument, but forgets that in real life, things don't always work out as well as they do on paper. TrailblazerSS summed it up perfectly. Sure, your argument sounds great in an IDEAL situation, but I'll be suprised if you seen that great of an increase in MPG, and I mean really, is 1-2 MPG worth all that hassle???
But back to my point, from the sounds of your priorities, why in the heck would you buy an SS just to hack it up for fuel economy? On one side you are looking to reduce the performance by changing the gear ratio to gain MPG, but on the flip side you want to do exhaust work to enhance performance? Since you are hooked on numbers in ideal situations, 2 drivers in identicle vehicles with different ratios will have 2 very different performing vehicles. Saying you would still beat a 4.10 SS with 3.73's or 3.42's assumes a lot man. A decent driver is going to have no problem launching with the 4.10's. You throw a set of 3.42's in there and you are going to be right back at the 5.3L TB performance numbers, regardless of torque.
Have you ever modified a vehicle? I mean, have you ever changed things out to see effects, like rear end gears, or heads, or cams? And taken measurements, before and after, isolating variables, to see exactly how your modifications have changed things? I have, and I have done so on LS1 motors. Can you say the same? From the way you're coming at me, I doubt you have.
To listen to the reasoning some of you are putting forth, GM should have put 4.56's in the TBSS to start with. I mean, more is better, right? :duh:
Going to 3.73's on a TBSS will, IMO, result in gains in the mileage department with relative little (if any) loss in performance. Plus the comfort at highway speeds will increase due to a decrease in noise. With a 30" tire and 400 HP, the 3.73's is clearly the more efficient gear for all-around performance, given the limitations of the 4L70 gear ratios. If you were talking 32" tires, then 4.10's would most assuredly get my vote, but with a 30" tire, 4.10's are overkill.
My opinion is that GM missed the boat for the best gearing for an all-around vehicle. It was likely an emotional decision based on fear. They went after specs for magazines - two specs that are relative meaningless to 95% of the market out there. I mean, who is buying a TB SS to tow? Come on. And who is going to be racing their TB SS every day? Those are the two things the 4.10's are good for, plus eating gas at highway speeds.
Aerodynamics is one of the biggest factors with gas mileage. You are essentially trying to push a brick, instead of a smooth object through the air. The USAF has done this before with the F-4 Phantom. It proved if you put enough power behind something it will move effectively. Then the F-16 came along over 26 years ago with a single engine and outpowered the F-4.
Been following this thread, couldn't resist. I was stationed in Alconbury, England with the 527th (F-5's) and the running joke was that the RF 4-c was proof that a brick would fly. :yes: :rotfl:
jimmyjam
10-06-2005, 09:35 AM
Personally, I would never make major mods to a car still under warrantee, but I'm all for someone else doing it to theirs! Congratualtions for having the extra money to burn! I'd love to see before and after statistics but I think the fact that the car won't be broken in yet when the baseline is taken will skew the results. Anyway have fun!
It was likely an emotional decision based on fear.
WOW! Fear is a pretty strong word too. I suggest it had little to do with "fear" and everything to do with developing a package that delivers truly significant performance in this vehicle class.
They went after specs for magazines - two specs that are relative meaningless to 95% of the market out there. I mean, who is buying a TB SS to tow? Come on. And who is going to be racing their TB SS every day? Those are the two things the 4.10's are good for, plus eating gas at highway speeds.
Towing capacity is a significant selling point in the truck market, regardless of whether it is a concern for you personally. Look at the truck ads, it's a central focus. I suspect personally that the towing thing is a nice benefit of the axle ratio and powertrain selection in this case, but maybe not part of the ultimate goal.
The performance aspect (a sub 6.0 advertised 0-60) is something that the Performance Division carries as a key goal. This is a program engineered somewhat outside the mainstream, with a pretty specific focus. It could certainly be argued that many performance vehicles (like the Corvette you quote frequently) are not great "real-world" or "all around" vehicles for most buyers. I suggest that the TBSS is not a car for everyone, but rather a niche performance piece that is probably intended as much an "image vehicle" as anything.
Your personal goal for your TBSS project clearly has a different ultimate goal (and therefore different requirements) than what the program team apparently had in mind. That's OK - that is what the aftermarket is for. I would suggest some seat time in one of these trucks before too many strong conclusions are drawn. At this point it's all speculation and as one poster described - "bench racing." I will exercise my own opportunity to simply disagree with the comments like "missed the boat," "decision based on fear," and some aspects of your analysis. Fair enough?
Without question the fuel economy of the TBSS is poor. Could it be better? Probably, but it seems fairly clear that FE was not a key aspect of the program when it was conceived. Is it "the wrong answer" with fuel prices the way they are at the moment? Maybe so. All that said, if I could predict market fluctuations, significant weather events (like multiple Cat4/Cat5 hurricanes), and politics 2-3 years in advance (realistic program lead time), I sure as hell wouldn't be sitting here posting on trailvoy.com...
Either way, as I said in my earlier post, best of luck with your project, it will be interesting to hear how things go.
westbayou
10-06-2005, 11:15 AM
---- Dude, if GM missed the boat (your words, not mine), why in the heck are you planning on buying an SS? GM has said this is a niche performance vehicle, not built for everyone. What I am getting from you is "Man, GM screwed this thing up by gearing it wrong and putting in a weak tranny, its junk, but I'm gonna buy it anyway." It cracks me up sometimes how the average backyard mechanic seems to know better than they fleet of highly compensated engineers that GM has working for them. Its your vehicle, do with it as you please, but I sure as heck don't understand your thinking.
Oh, and as for my qualifications, I finished a heads/cam swap on my brother's LS1 Trans Am last weekend, I hand built the perfomance engine in my Jeep, actually built the Jeep from the ground up. So yes, I know my fair share about modifications and what they can do for a vehicle.
a990dna
10-06-2005, 11:29 AM
These are the most likely reasons, although gear changes don't result in changes in 1/4 miles times as much as they result in a higher trap speed with similar times. A faster 0-60 is the more likely reason, being as this spec is thrown about more often in the mainstream auto press, and the 4.10's definitely help here. And at the expense of MPG and freeway driving comfort, I might add.
Not sure this is such a win-win, unless you are buying a TBSS to race. Great, so the 4.10's got GM the specs they wanted, but at what cost? If you will be driving it daily to work, going on trips, etc., the 4.10's are a poor choice, IMO. If you never spend any time on the freeway, then it will be fine, but if you spend 50% or more time at 65 MPH or greater, the buzzing will get old very quickly. There is a reason a Corvette has a .50 6th gear.
If you think 400 HP with 3.73's and a 30" tire is going to have any problems at all with anything, like driving up a mountain, then you haven't had much experience with the '3' position, or the '2' position on your gear selector. That's what it's there for. You'll be doing the same thing with 4.10's.
To listen to the reasoning some of you are putting forth, GM should have put 4.56's in the TBSS to start with. I mean, more is better, right? :duh:
My opinion is that GM missed the boat for the best gearing for an all-around vehicle. It was likely an emotional decision based on fear. They went after specs for magazines - two specs that are relative meaningless to 95% of the market out there. I mean, who is buying a TB SS to tow? Come on. And who is going to be racing their TB SS every day? Those are the two things the 4.10's are good for, plus eating gas at highway speeds.
Getting back to your original question... based on all this input, which version have you decided? 2WD or 4WD?
Now I have a question: Why are you considering this vehicle?
I believe you have made it perfectly clear that GM hasn't met your expectations.... or specs.
In my world there's no substitute for cubic inches.... hence the a990.
As far as lack of experience shifting gears... when you buy your new sled bring it out, with the pink. I've got a few gear changes I'll show ya...
Oh yea, how is that ROI working out?
I swear, some of you act like I've threatened your child! :eek: Geez Louise, I'm not talking about dumping nuclear waste into your neighborhood, or kidnapping your wife, I'm talking about modifying a vehicle that I'm considering buying. Believe it or not, for the most part, you will remain unaffected. :duh:
It appears the person most capable of having a conversation on this without totally going off the deep end is SBK. Your questions and observations are well received, and I appreciate your input. Yes, my requirements are a little different, and that's why I am considering making a small adjustment - a 10% change in gearing. Believe it or not, guys, that's a fairly small change. But it's a change that I believe would have more benefits than detriments, at least for me.
My requirements are exactly this - I want an all-around nice, cruising vehicle capable of carry 4 adults in comfort, that has excellent power and performance, and doesn't get really bad gas mileage on the freeway, where I spend 80-90% of my time driving. The place I want performance the most is on the freeway, when I am already moving, as in 60-80 MPH, or 70-90 MPH. I will seldom be racing from stoplight to stoplight, which is a place where 4.10's will shine. However, I am confident that with a 30" tire, 3.73's will do just fine off the line.
If all I did was drive around town stoplight to stoplight and didn't go above 45 MPH for the most part, then I would be content with the 4.10's. As a matter of fact, they would be ideal. If I towed something heavy, I would certainly get the 4.10's, but I don't anticipate towing anything, except for perhaps some jet skis. The only other reason I can see for getting 4.10's is to race the vehicle from a stop. In my experience, after 20 or 30 MPH the 4.10's have lost their usefulness and the 3.73's are just as good. Since I'm not into racing from a stop, there really is no reason for me to have 4.10's.
As far as the comments about me 'hacking up' the vehicle, or people saying 'performance will suffer greatly', or all the talk about ROI, it's clear that people have their own pet issues that I don't share. If you make a modification to a vehicle and it turns out poorly, then you really should not be working on cars. Regarding performance suffering with a 10% change in gearing, go ahead and believe what you want to believe, I have experience that says otherwise. And as far as buying a vehicle as an investment....:rotfl:
I believe everyone has chimed in here because they can not believe how rediculous of an idea it is to swap to a lower gear for reasons that do not make any sense. If you are that worried about gas mileage that you are sacrificing performance for 1-2 miles per gallon, are you going to be relucant to stomp on the gas to use all 400 ponies? I mean, if you went WOT for about an 1/8 mile, you may only get 5 miles per gallon. That would negate about a weeks worth of gas savings from your gear swap :laugh: .
Why are you getting an SS in the first place? I work in the industry and have intimate knowledge of the LS2 - where did you hear that crap about "efficieny range"?
Why are you getting an SS in the first place? I work in the industry and have intimate knowledge of the LS2 - where did you hear that crap about "efficieny range"?
Did you read my last post? If so, you would know why I am getting an SS.
Please share with us your position in the industry, and what you know about the LS2.
a990dna
10-06-2005, 01:54 PM
And as far as buying a vehicle as an investment....
If this is in reference to the ROI.... who said anything about buying one of these for an investment? The ROI is based on your desire to spend extra money to improve gas mileage and reduce operating costs... your plan doesn't do that.
Now, if you came here and said I enjoy tinkering and spending money on my DD... then do whatever your heart desires. I do stupid things too. To be honest, if the 3.73 was an option on the SS package, I personally would order it that way.
Yes you're correct.... SBK understands how Programs are conceived, researched, approved, managed, and released to market. I believe he was especially articulate in explaining this business process. I understand his insight and the concept of global commercialization... with the primary goal of capturing market share and inking out profits.
Believe me, if it wasn't for the SRT-8, SVT, TRD efforts... we wouldn't be discussing GMs SS line.
BTW, you must be as old as me.... "Geez Louise"? I haven't said that since the mid-70s. I also haven't had a good bench race since then... thanks for the memories :rotfl:
Windy City
10-06-2005, 02:41 PM
I don't want to contribute to the discussion about if it's right or wrong but...
The way I would do it would be to drop down to 3.73's and use a fairly loose lock-up converter. The best of both worlds. A good converter will easily make up for the lower ratio and 3.73's might actually help with the launch so you don't over-power the tires as easily. The performance gains with a good converter should be substantial. Just invest in a top-quality tranny cooler and temp guage.
If you're looking to keep it mostly stock and don't want a converter, maybe consider a Gear Vendor's underdrive/overdrive unit. It would add weight but it would also knock your RPM's way down at cruise and you could keep the 4.10's.
My :m2: why GM used 4.10's? For performance off the line and towing without reverting to a looser converter (also higher STR) which in the long term would reduce tranny life due to higher fluid temps. A higher STR would also put more strain on the tranny and GM's main goal is longevity.
None the less, this thing is a brick so I wouldn't be too optimistic about obtainable mileage but all the power to you if you can acheive your goal of 20+ MPG average.
Jman423
10-07-2005, 12:33 AM
Lets tone it down a little, some of you are getting all offended about someone's opinion!! If you don't like someone elses opinion, "agree to disagree" and move on to the next thread. :cool:
APDMC6008
10-07-2005, 01:00 AM
BTW, if you run the numbers it will take you approximately 6-7 years to recover your modification costs. It doesn't make financial sense to do this....
Example:
Net MPG Increase 1.5
Tank Gallons 20
Additional Miles per Tank 30
Average MPG 18
Gallons Saved 1.67
Cost per Gallon $3.00
Savings per Tank $5.00
Modification Costs $2,000.00
Savings per Tank $5.00
ROI (Number Tanks) 400
Fill Ups per Year 52
ROI (Number Years) 7.7 (Break even point)
Cash Investment $2,000.00
401K, IRA 6.00%
Number Years 7.7
Non Compounded Gains $922.80
That's what I'm saying...LOL. I mean seriously.....
TrailblazerSS
10-07-2005, 01:37 PM
Like I said, if I do this, I'd be more than happy to race you. :D
Hey I believe the changes you are talking about won't make much of a difference. It will be driver skill not equipment differences. as for mileage increase, don't count on it.
As far as racing goes, I'm getting AWD, you're guning for a 2WD. But I'll tell ya what I'll show up in the TBSS for the race, BUT, behind it will be a trailer (notice the TBSS is doing what it is designed to do.) I'll race ya with what I unload off the trailer. Even though it's a 7 year old beater......:eek:
After all there was another thread here proclaiming that the TBSS's would compete with f-bodies.....:laugh:
a990dna
10-07-2005, 02:35 PM
If you guys live close enough to race each other (socal), you may live close enough to go see and sit in a production TBSS. They have one sitting on the floor at the California International Auto Show in Anaheim this weekend.
A white one...
Cockpit is nice.... however, I wouldn't want to be one of the adults stuck in the back seat on one of those long trips.
dmonwai
10-09-2005, 07:22 AM
I mean, who is buying a TB SS to tow? Come on.
I would be.
I tow a boat every weekend.
I am currently researching my next SUV to buy. The TB SS is very high on my list. Towing capacity and towing performance is very important to me. I used to race superbike motorcycles for over 10 years, so I really like power and performance.:)
I would also be using it for my everyday driver. My next SUV needs to be able to tow my current boat (small and light almost anything can tow it) and my next boat, which will weigh about 5000lbs. Having great non-towing performance is very appealing. I want to stay with a mid-size SUV because of the daily driving that I do. My brother used to have a Expedition and now has a Tahoe. I have driven both of them a lot and they are larger then I would like to drive on a daily basis where I drive. Thats why I'm seriously considering a TB SS as my next SUV.
My main point is that towing capacity/performance is very important. I'm sure that a lot of people would use it for towing in my area.
a990dna
10-09-2005, 09:38 PM
I'd like to see where this dual exhaust is going to be routed... I looked underneath the TBSS and the fuel tank consumes most of the space under the driver side from the axle forward. It would be an unusual and difficult route to get a 2.5" exhaust pipe from the left bank to the left rear.
It pretty much eliminates the possibility for a H pipe and the dual exhaust will have unequal lengths....
NOT exactly a performance setup in my book!
ScarabEpic22
10-10-2005, 12:22 AM
YESSSS, a Seattle member!!!:D
Welcome to the site man, and good luck with your (hopefully) TB SS. My 02 LT is nice, but I really want a SS.
Fellow members!
I am going to close this post because I feel this topic is not benefiting anyone, only making people angry.
I give credit to anyone that is willing to try to make their vehicle better, but I also give credit to people that give advice about that procedure. It should never result in attacking another member (this is only a vehicle that we are talking about).