Jump to content

6.2/6L80/3.73 vs 6.2/8L90 vs ???

tdc5152
 Share

Recommended Posts

tdc5152 New Member

tdc5152

Posted
Posted

Long lurker, but first post. I’ve done quite a bit of educational reading here on many threads and wanted to inquire on something. 
 

I’m in the market for a 14-18 Silverado or Sierra 1500. Ironically, I have an opportunity to score a very nice, almost ridiculously nice, condition 2014 6.2 SLT with the max trailering package (3.73) and acceptably low mileage. It has almost all, minus a few not so important, options I’d like. 2014 is really the only way to get one of these trucks w/o getting the 8 speed, unless I’m mistaken, so between that, age/mileage, and certainly factoring in the max trailing pkg, such a combo is difficult to find. Plenty of options exist to get the big motor in 15-18 trucks with the 8 speed, with max t pkg if necessary. 
 

Now, I don’t know that I’d go so far as saying that I prefer the “smoothness” of the 6 speed relative to the 8 speed but in our Yukon XL SLT (5.3/6 speed), honestly it offers a rather pleasant city and highway driving experience lugging around the kids. Mind you, we aren’t racing it with the kiddos onboard. It’s not quick, by any means, but it does the job.  I’d want more in a truck, thus the 6.2 thinking. Now, I’ve driven 5.3 + 8 speed combos and other non GM > 6 speeds, and they always feel jerky to me when doing simple cruising around town. I don’t feel it matters much on the highway, honestly. At elevated speeds, the feel difference is minimal IMO. I have NOT driven a 6.2/8 speed….yet. 
 

The general consensus in my reading here is that the 3.73 ratio in the 6 speed really makes the 6.2 come alive - several threads about towing (which I don’t do a lot of), quickness/fun-ness (important to me), etc. In addition, one might even say some feel the 8 speed should be avoided, others say just jump to the 10 speed. Opinions vary.
 

My question is, given the 8L90 issues, short lifespan relatively, etc does it make any sense to specifically consider an “older” 6.2/6L80/3.73 vs a 2015-2018 6.2/8L90 combo?  Or have a lost my mind completely due to information overload?  My primary concern is long term durability/reliability. Obviously, I don’t want a train wreck, and first year roll outs in a series always make me a little nervous even though the truck in question literally has been near flawless across its life. 
 

Curious what you connoisseurs and those having more experience in all these combos might do here - consider the 6.2/6L80/3.73 purchase, re-focus on a 6.2/8L90 - with or w/o NHT (I think is the code), or sit tight until a 6.2/10’s come into my budget a year or so from now? 
 

 

redwngr Senior Enthusiast

redwngr

Posted
Posted

Diff ratios used on 8 speed are different that 6 speed.

 

I think you find that the overall ratio (trans and diff) with the 8 speed gives a lower low and a higher high than the 6 speed. 

 

Same deal with the max tow (NHT versions) which has higher (numerically) ratio diff's.

 

 

  • Like 1
JimCost2014 Senior Enthusiast

JimCost2014

Posted
Posted

My 14 (non max tow package) had the 3.42 6 speed, very quick truck off the line, and held RPM's a little higher, not as much 'lugging" at lower speeds.

 

The 16 I had, and now my 18 have/had the 3.23 8 speeds. Both have been very good, but takes a little more "motivation" to get them going at the same pace as my 14. Better MPG's with the 8 speeds, and tow just fine.

 

If you are looking at K2's, would really consider an 18, seems like it was the year they finally got most of the bugs worked out IMO.

  • Like 1
Gangly Senior Enthusiast

Gangly

Posted
Posted

I posted a gear ratio spread sheet a while back comparing the 6 speed with 3.73's to the 8 and 10 speed  with the 3.23's and the 8 and 10 speed had "lower lowers and higher highs" as posted above.  The key though isn't how "low" the overall gear is, its how long the truck stays in that gear range and the 8spd and 10spd manage to operate in the lower gear ratio parameters for a longer duration than the 6 speed which in turn allows the vehicle to pull harder for longer even though the rear gear ratio is taller.  I'll see if I can find my spread sheet and post it again.

  • Like 1
Gangly Senior Enthusiast

Gangly

Posted
Posted
6 Spd Auto Gearing (X:1)   4 Hi Final Ratios 4 Lo Final Ratios
1 4.03   15.03 40.44
2 2.36   8.80 23.68
3 1.53   5.71 15.35
4 1.15   4.29 11.54
5 0.85   3.17 8.53
6 0.67   2.50 6.72
         
         
Reverse 3.06   11.41 30.70
         
Axle Ratio 3.73   Crawl Gear Ratio (X:1)  
      40.44  
Transfer Case        
4 Hi 1      
4 Lo 2.69    

 

 

 

 

 

8 Spd Auto Gearing (X:1)   4 Hi Final Ratios 4 Lo Final Ratios
1 4.56   14.73 39.62
2 2.97   9.59 25.81
3 2.08   6.72 18.07
4 1.69   5.46 14.68
5 1.27   4.10 11.03
6 1   3.23 8.69
7 0.85   2.75 7.39
8 0.65   2.10 5.65
Reverse 4.86   15.70 42.23
         
Axle Ratio 3.23   Crawl Gear Ratio (X:1)
      39.62  
Transfer Case        
4 Hi 1      
4 Lo 2.69      

 

 

 

 

10 Spd Auto Gearing (X:1)   4 Hi Final Ratios 4 Lo Final Ratios
1 4.7   15.18 40.84
2 2.99   9.66 25.98
3 2.15   6.94 18.68
4 1.8   5.81 15.64
5 1.52   4.91 13.21
6 1.28   4.13 11.12
7 1   3.23 8.69
8 0.85   2.75 7.39
9 0.69   2.23 6.00
10 0.64   2.07 5.56
Reverse 4.87   15.73 42.31
         
Axle Ratio 3.23   Crawl Gear Ratio (X:1)
      40.84  
Transfer Case        
4 Hi 1      
4 Lo 2.69      
  • Like 2
  • Thanks 1
Gangly Senior Enthusiast

Gangly

Posted
Posted

Those are based on my own calculations from materials I have reviewed.  The reverse gear ratios would need to be validated.

 

Basically, the 8 speed and 10 speed transmissions do everything better, from top to bottom, even when the 6 spd is paired with the 3.73's.  If you pair the 6L80 with 3.42's or 3.23's then the 6l80 is not even remotely close.  The only real question would come down to reliability in which case the early 8 speeds did have issues but those same issues seem to be resolved in the newer models.  I have not had a single hiccup from my 2020 8-spd and I have 45k miles on it.

  • Thanks 1
pokismoki Senior Enthusiast

pokismoki

Posted
Posted (edited)

if you can score a clean truck pre-2017 get that sona-******, , the computer are easier to access and tune.

i know the tuners like the 8 speed because it can handle over 1000hp, but cost is not friendly for the home tuner. tcm unlocks $$$ the 8 speed can shift faster, but has way more rotational mass which robs you of power transfer.

 

6l80/90 is the way to go if you want tuning on a budget, the 2500 trucks is the best 6 speed, its built stronger as a 6L90.

Edited by pokismoki
newdude Senior Enthusiast

newdude

Posted
Posted (edited)
On 10/15/2021 at 7:51 PM, tdc5152 said:

Long lurker, but first post. I’ve done quite a bit of educational reading here on many threads and wanted to inquire on something. 
 

The general consensus in my reading here is that the 3.73 ratio in the 6 speed really makes the 6.2 come alive - several threads about towing (which I don’t do a lot of), quickness/fun-ness (important to me), etc. In addition, one might even say some feel the 8 speed should be avoided, others say just jump to the 10 speed. Opinions vary.
 

My question is, given the 8L90 issues, short lifespan relatively, etc does it make any sense to specifically consider an “older” 6.2/6L80/3.73 vs a 2015-2018 6.2/8L90 combo?  Or have a lost my mind completely due to information overload?  My primary concern is long term durability/reliability. Obviously, I don’t want a train wreck, and first year roll outs in a series always make me a little nervous even though the truck in question literally has been near flawless across its life. 
 

Curious what you connoisseurs and those having more experience in all these combos might do here - consider the 6.2/6L80/3.73 purchase, re-focus on a 6.2/8L90 - with or w/o NHT (I think is the code), or sit tight until a 6.2/10’s come into my budget a year or so from now? 
 

 

 

 

6L80 has a higher issue rate than the 8L90, at least where I work.  All day long.  I've lost track on how many 6L torque converters we've done, on how many got fluid pumps and some internals, on 4-5-6 clutch failures, entire transmission replacements because so much converter clutch material an metal went through them.

 

8L90 I would go 2018+newer.  If it hasn't had the fluid swapped out for shudder that would be the first thing to do.  Some of the funky shifts can be settled out by making that specific gear change like 15-20 times at the throttle % it does it.  Helps to learn that clutch/gear change.  So say you have a funky 2-3 shift, pop it into manual mode and make a bunch of 2-3 shifts.

 

As far as how they run/drive.  I'm on my 4th 6L.  I love them for the most part, but 8L and 10L drive sooo much better, especially the 8L in the T1 new trucks.  They tightened up the shift calibrations and tuning much better.  

 

3.73/6speed vs 3.42/8speed.  The 3.42/8speed would have even more gear multiplication throughout 1-4th or 5th gears.  8 speed lets the engine sit in the HP and or TQ bands better.  Watch some of the Ike Gauntlet videos on TFL truck.  Yes, the test is a more extreme test and and high elevation, but you can see where some of the GM 6 speeds fall short of the 8 and 10 speed trucks.  6 speed can get stuck in a lugging zone and start to fall off RPMs and out of the meat of the power range.  Even with 4.10s.  

 

6.2 8 speed NHT 3.42

2017 Chevy Silverado 1500 6.2L V8 vs Ike Gauntlet Review: World's Toughest Towing Test - YouTube

 

6.0 HD 6 speed 4.10

2015 Chevy Silverado 2500 takes on the Grueling Ike Gauntlet HD Towing Test - YouTube

 

6.6 new gas HD 6 speed 3.73

The New 2020 Chevy Silverado HD Gasser Broke Our Ike Gauntlet Scoring System - Here Is How! - YouTube

 

I know there is weight differences in the videos above, but you can still see how the two HD trucks get put in strange positions during the pull.  The switch DOWN to 3.73s in the 2020+HD was a mistake as well.  That truck needs the 10 speed all day long with those 3.73s.  

Edited by newdude
  • Like 3
  • 2 weeks later...
tdc5152 New Member

tdc5152

Posted
  • Author
Posted

Sorry all.  I've been away on business for a bit.  

 

Thank you for all your input.  This clarifies a lot of question marks I had.  Now it's time to take a few different configurations for a spin and complete the "feel" evaluation.  

 

Besides, the used car value/market is completely out of control (high) at the moment, so exercising a little patience is probably a good idea honestly.

 

Thanks again.

  • 1 month later...
Transient Senior Enthusiast

Transient

Posted
Posted
On 10/29/2021 at 7:35 AM, pokismoki said:

wow, on the 10 speed that 1st (4.7)gear transition to 2nd (2.99)gear must be an annoying shift

Nope.  Not at all. 

redwngr Senior Enthusiast

redwngr

Posted
Posted (edited)
17 hours ago, Transient said:

Nope.  Not at all. 

Agreed. 

Behind the 3.0 it is buttery smooth. 

 

(is that a technical description??)

Edited by redwngr
M1ck3y Senior Enthusiast

M1ck3y

Posted
Posted (edited)

It's too bad we won't get to see a 12 speed. Four or Five overdrive gears would have been great on the highway.

Edited by M1ck3y
M1ck3y Senior Enthusiast

M1ck3y

Posted
Posted (edited)

Interesting fact. A lot of people complain about the gearing being so low compared to competitors. But if you pick the correct (Taller tire) for your application you can reduce your 0-60 mph etc.

 

For ex. I put on slightly larger tires changing the axle ratio to 3.19 from 3.23. I know, small change. But enough that it now shift's just after 60mph and the 1/4 mile making better time. A lot of factors in this. But if you're traction limited a taller tire could be the way to go. 

 

That is, if you use trucks for things they weren't intended for 😜

 

And taller tire's cover more ground. Less rpm for distance traveled so.. quicker at higher speeds

Edited by M1ck3y
Transient Senior Enthusiast

Transient

Posted
Posted
6 hours ago, redwngr said:

Agreed. 

Behind the 3.0 it is buttery smooth. 

 

(is that a technical description??)

I have the 6.2.  That's 2 engines with the same trans both agreeing.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • AidenVorpagel
      cam upgrade in CA

      By AidenVorpagel · Posted

      hello I recently bought a 2012 gmc 1500 with a 5.3 and have a AFM disabler on it I'm interested in doing a cam but I'm worried if I remove the AFM system I will fail smog does anyone have info if they are able to detect that or a work around to it (not talking about hot smogging) please let me know thank you  
    • B14Sierra
      Noise after AFM delete

      By B14Sierra · Posted

      Did you figure it out?
    • B14Sierra
      Possible lifter tick after DOD delete

      By B14Sierra · Posted

      Update. I started chasing down my symptoms. Started first with pulling valve covers and looked at everything. Everything looked good and couldn't hear or feel anything different. Then a compression test. 240 psi or really close on each cylinder. I was worried I was a tooth off of timing. Not bad for an engine with 173,000. Granted I did put new heads on. I sprayed water around the injector area to see if I could hear a change. Nothing. I hooked up my new hp tuner which I should have done in the first place but I don't really know what I'm looking at just yet but am learning. I noticed the fuel trims were way off so that told me I have to have either a bad injector or exhaust leak. New injectors, so I did the shop vac on blower and in the tail pipe. Sprayed soapy water and found the exhaust flange on the drivers side was leaking. I didn't think it would be that considereding I pulled the heads and left the manifolds attached. I did have the transmission replaced not long ago. They must have not seated them properly but I guess I didn't notice. I put in new gaskets on both sides. Which by the way isn't a bad job but I had a hard time getting them to seal right. Took two attempts. Reset the fuel trims and the ticking is gone, engine runs smooth and acceleration has improved. Got to feel the real difference with that stage 1 cam. It's not that big of a difference but it does add a little more. It feels like how the truck should have been from the factory.
    • Grumpy Bear
      Some Assembly is Required

      By Grumpy Bear · Posted

      Can it still be Assembled I?    Stribeck says that we need a certain amount of viscosity under conditions of load and velocity to prevent two surfaces of a know roughness from tearing each other asunder. And we have marketing trying to tell the masses that those two surfaced require less of that commodity due to more exact limits being placed on the same old clearances. We also know that there are limits to how hard something can before it becomes to brittle to be viable and to smooth to 'wet' the surface and that both of those conditions have been known and met since about the Second World War.    That viscosity value shook out at 10 centistokes at 212 F just under a hundred years ago.  Give this a look: [Anton Parr]     What is advertised is the Kinematic viscosity (mm2/s) or that which has been density adjusted but the value we are after is the dynamic viscosity (mPa.s) or true viscosity. You can see that this number is dependent on density thus base stock and temperature. You can also see that an SAE 30 doesn't reach that value in this example. However an SAE 30 that is at the upper end of the SAE 30 range; 12.5 cSt (mm2/s), might. 12.5 * .83 = 10.375 (mm2/s). If you could find an SAE 30 at the upper end these days.   Then there is the complication of viscosity modifiers or VII or VM, whatever you wish to call them. Polymers added to very thin base oils, perhaps 3 to 6 cP oils, that will meet the SAE *W30 spec at 'tested' shear rates and 100 C/212F  target temperature. So a polymer fortified base that is a fraction of the 10 cP requirement Stribeck insist upon.   This could be all well and good if those polymers didn't have two very problematic 'features'. They shear or loose viscosity both 1.) permanently and 2.) temporality. And they do both omitted in the advertised data with the distinct  purpose of deceiving the consumer of the actual operating state of the fluid. I've shown the example of Warren Oils COSTCO 10.91 cSt 5W30 formuation several times where the 100 C HTHS value is 6.9 cP!! That's the temporary shear down and with and SSI or shear stability index of 9.4 cSt. Note the intentional deception in using mixed units?    After a short while that 9.4 cSt oil has a viscosity corrected dynamic value of 7.8 cP. But as the SSI is still within the range of an SAE *W30 whose lower value is 9.3 cSt.    This allows them to continue to call this SAE 16 weight oil a 30 weight, the cake, and still meet the API requirements for fuel efficiency IMPROVEMENT mandated by the EPA. The eating of the cake. By the time you've worn out your motor doing the responsible thing by adhering to the warranty requirements, (the stick), you get deprived of the carrot, wear control. So sad, to bad.   So what can be done? Do I need actually say? [Anton Parr]       Even this must be monitored if the oil is on the low side and the VII an organic or you opt for a 0W40 with an even lighter base oil and more / higher MW VII. (Note the lower density of the 40 weight versus the SAE 30 mono-weight?)    There is another workaround. Temperature. An SAE *W30 run at a bulk temperature of between 180 and 195 F.    Being the belt and suspenders sort I am I do both. Run it cook and run it heavy.    In Part II I'll work the AW package. 
    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      So, do I go elbow-deep on this thing or list it for sale and play dumb? Seems to "runs good."   I'm about $1200 away from having: -a rebuilt injector ($300) -a new cat ($250) -a new cat back exhaust (OE style) ($300) -a new AC compressor ($200) -AC refrigerant charge ($150)   In theory, this should rectify the obvious detracting issues from its value and operability. Cold AC with a non-squeaking AC pulley both sounds and feels good. An exhaust that isn't cut/hacked in 17 different places and doesn't vibrate on a crossmember would make it sound and feel less janky. A working cat would help the stink, and will save the earth, but *if and only if* the fuel system is working properly, which would also address the intermittent "rich" CEL.   Heard a good one... CEL for "Rich condition" means you haven't spent enough money on the truck lately, and it's letting you know.   Rebuilding the injector would seem to be the most important part. Replacing the cat would be secondary. I don't think mine is plugged or overly restricted, but it might be a little restricted? I have no good way to tell other than seat of the pants feel. I hate the smell.   The current theory is I have a rich idle problem: A bad fuel pressure regulator, or a leaking injector(s) being the highest probabilities. I already replaced the FPR but that doesn't mean its replacement isn't also bad. It was a new part from Dorman, but the packaging looked like it had been sitting on a shelf for 20 years.   This is the (single) upstream O2 sensor shown at idle. I'm getting a lot of "rich" it seems. Sometimes it stays high like that and doesn't drop down. That makes me think it's processing injector leaks or a partially stuck open injector.     Other times it looks like this. Nice oscillations between rich and lean, which is what I think it should be. Under load and at speed, the oscillations are nice and tight and uniform looking, high and low.     Fuel trims suggest the PCM is compensating pretty hard at idle to pull fuel out. But it's not enough to trip a CEL. Something about slowing to a stop: brake vaccum booster, EGR, or the EVAP purge is delayed, or there's pooled fuel in the intake again that's draining into a cylinder is enough to set the CEL. Of course, in two days of driving, it hasn't set. I was hoping to actually look at the freeze-frame data when it sets. IAT is high because it's idling on an 83 degree day here.  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...