6.2L (L9H) Owners - Get all your questions answered here

[Bvancura6.2]

Has anyone put on the banks ram air with the super scoop if so wondering your thoughts and any comments welcomed the super scoop makes sense as far as an actual functioning cold air intake

[6.2 Denali AWD]

Love the 6.2L section. Thanks, and I hope to be able to contribute useful info

over time. Couple pics of my six.two...

 

[6.2 Denali AWD]

Avatar shot...

 

[michigan2500hd]

So what as far as looks sets the 2014 trucks with the 6.2 apart from the rest that have the 5.3 and 4.3 ? With the 09-13 trucks you can see the larger exhaust routed out under the bumper and the 14 bolt rear dif. Do the 2014's all have the smaller exhaust pipe?

[txmuder]

Seems the 14's w/6.2 is a little larger the the 5.3's but both are angled out the same and somewhat difficult to tell apart IMO.

[RyanbabZ71]

The 14 isn't an L9H motor

 

 

Ryan

[michigan2500hd]

Yes I realize it's quite a bit different I was just wondering why they didn't put a larger exhaust on it like our trucks. Which makes me wonder if the L9H really needs a 3.5" pipe. Not that I'm complaining I just like to know the reasoning behind things like this.

[EX-F150 owner]

Could the pipe size be smaller do to the added AFM?

[NemesisC5]

Could the pipe size be smaller do to the added AFM?

 

That would be my guess, primarily to work best with the muffler / butterfly valve enhancing exhaust note and controlling drone.

[2010LTZ4x4]

So what as far as looks sets the 2014 trucks with the 6.2 apart from the rest that have the 5.3 and 4.3 ? With the 09-13 trucks you can see the larger exhaust routed out under the bumper and the 14 bolt rear dif. Do the 2014's all have the smaller exhaust pipe?

So does the 2014's come with the 14 bolt rear end with the 9.5 ring gear???

['01LS1]

So does the 2014's come with the 14 bolt rear end with the 9.5 ring gear???

 

Wanting to say that there were going to be three different rear ends(not gears) matching each of the new engines?

May be wrong on that as it was info from when they were announcing them.

 

But this is current GM media for the K2xx 6.2L set up.

 

• The available 6.2L EcoTec3 V-8 is the most powerful engine offered in the light-duty segment, with 420 horsepower and 460 lb-ft of torque. Like other EcoTec3 engines, it combines proven performance with advanced fuel-saving technologies, seamlessly switching to four cylinders to improve efficiency in light-load driving
• The available Max Trailering Package includes a 9.76-inch rear axle, heavy-duty rear springs, revised shock tuning for increased control, enhanced cooling, and an integrated trailer brake controller. Also included is the G80 locking rear differential, a trailer hitch, and bumper-mounted four- and seven-pin connectors
• Sierra’s standard 4.3L EcoTec3 V-6 and available 5.3L EcoTec3 V-8 also will offer significant towing capability for 2015, with maximum available trailer weight ratings of 7,600 pounds for the V-6 and 11,200 pounds for the 5.3L.

http://media.gm.com/media/us/en/gmc/news.detail.html/content/Pages/news/us/en/2014/Jun/0619-gmc-sierra1500.html

[Roll Bama Roll]

Yes I realize it's quite a bit different I was just wondering why they didn't put a larger exhaust on it like our trucks. Which makes me wonder if the L9H really needs a 3.5" pipe. Not that I'm complaining I just like to know the reasoning behind things like this.

3" will support the horsepower but improve the low end quite a bit due to better low rpm exhaust velocity. I've been experimenting with narrowing the exhaust diameter after the muffler on my 2013 6.2 for the past few months. The motor responded very well, however I do have a Magnaflow to reduce restriction. But narrower worked much better than stock 3.5". Tried four different setups of varying lengths of narrowing. I settled on reduced diameter for the entire back pipe length because of the significant performance gains for my truck.

 

Edited November 27, 2014 by Roll Bama Roll

[CRSilverado]

3" will support the horsepower but improve the low end quite a bit due to better low rpm exhaust velocity. I've been experimenting with narrowing the exhaust diameter after the muffler on my 2013 6.2 for the past few months. The motor responded very well, however I do have a Magnaflow to reduce restriction. But narrower worked much better than stock 3.5". Tried four different setups of varying lengths of narrowing. I settled on reduced diameter for the entire back pipe length because of the significant performance gains for my truck.

 

Are the gains you are referring dyno or track proven? Edited November 27, 2014 by CRSilverado

[NemesisC5]

First, Happy Thanksgiving To Everyone!

 

Reducing exhaust diameter post y-pipe merge will not usually result in gains especially on a 6.2L. Power gains generally come from reducing diameter upstream to increase velocity thus increasing scavenging effect to evacuate non combustible exhaust gases from the cylinders leaving volume for clean combustible fuel.

 

The reduced exhaust diameter on the 2014 6.2L is more likely a result of controlling exhaust note with AFM (in 4 cyl mode along with butterfly valve in muffler) and possibly a cost saving measure going with 3" as opposed to 3.5" tubing.

 

I will follow up this post later today if possible with some information I gathered on the subject. Right now I'm off to eat Turkey!

[Roll Bama Roll]

Are the gains you are referring dyno or track proven?

Soon. That's an after Christmas project. Santa is supposed to bring me something from BB. I've got about 1200 miles on this setup but might tweak a little between BB and dyno.

 

On my setup, the dyno will reveal average magnaflow hp but peak torque will be shifted down a few hundred rpms, with torque coming on sooner and with a higher, broader, flatter torque curve until about 5200 rpm, where hp will be flat and torque will drop about 5% vs stock. I've done this enough that I can visualize it already. Now, as you can see, such a dyno chart wouldn't translate well into drag racing where you'd want to launch high rpm and hp wins. But on the street where there are lots of turns, acceleration, braking, lower tire speed ratings, speeding tickets, etc., torque wins.

 

Improving torque for daily driving has been a passion of mine for a long time. I'm a big guy pushing 275-290 depending on how many goodies get cooked between each Thanksgiving and Christmas. Years ago I had a single cylinder 650 motorcycle that was essentially set up like a single cylinder of a 318 cu in motor. Whatever you'd do to a 318 for performance the bike would respond likewise. But by being a single cylinder it removed many variables and allowed consistent modding analysis. I wanted to improve the low and midrange torque for daily riding. My buddy owned a bike shop with a dyno that I had full access to. A nearly two year project ensued of repetitive calculations, over a dozen prototype exhausts and a half dozen prototype intakes (all varying in length and diameter), post dyno analysis and so forth- all for the purpose of influencing torque curves and torque peak.

 

Ever since then, maximizing daily driver power became kind of an obsession. This practice has taken a lot of years to refine as the aftermarket industry traditionally pushes top end performance but frequently at the expense of low end. My neighbor owns a machine shop and has been truly vital to this pursuit.

 

Nothing bugs me more than spending money and time on a performance mod then, on my drive to work, realizing it made little if any difference during my drive, or worse, it resulted in performance loss during that drive. Or when I get nothing from it when the wife and kids are with me. Call it practical tuning, torque tuning, street tuning or whatever, I just know I prefer it.

 

But my posting here is because the 6.2 responded better to this particular exhaust mod than any other similar bike, car or truck projects in the past. Honestly, It sort of surprised me how well it did. And because of that I felt motivated to share.

 

If anyone here is going to be upgrading their 6.2 exhaust anytime soon, especially if you've got some type of freer flowing muffler already, before you do give it a shot just for sh*ts and giggles. Any local exhaust guy will have a couple direct fit 5.3 back pipes just laying around for free or maybe offer $5. Throw it on, drive for a week and see how increased flow velocity works out for your 6.2. I already know pretty much what your thoughts would be but I'd love to read responses.

Edited November 27, 2014 by Roll Bama Roll