6.2L & 6l80 Power Uprades

[ryaleon]

Now this has me thinking...it would be fun to build my own intake.

[H2Much]

Ryaleon, gears is your answer, especially if you are pushing 37's. that will give you the instant return to the stock feel once you get that ratio right. I suggest going 4.88's as that is as big as you can go on the front. Adding intake and exhaust and headers in that order will help too, but you need the gears first. Any time you go up in tire size you should be looking to regear so that your power gets rebalanced correctly. You don't do this, this is why you downshift so much. Your engine has almost 100 more horsepower stock so you have plenty of power. We have to do tons of mods just to get near where you are stock.

In short- regear is your answer.

[guruerror]

Originally Posted by H2Much

Ryaleon, gears is your answer, especially if you are pushing 37's. that will give you the instant return to the stock feel once you get that ratio right. I suggest going 4.88's as that is as big as you can go on the front. Adding intake and exhaust and headers in that order will help too, but you need the gears first. Any time you go up in tire size you should be looking to regear so that your power gets rebalanced correctly. You don't do this, this is why you downshift so much. Your engine has almost 100 more horsepower stock so you have plenty of power. We have to do tons of mods just to get near where you are stock.

In short- regear is your answer.

Agreed...'gears'...when I went to 37s the umph dropped. I moved to 4.56s and it ended up a tad snappier that stock. 4.88 will pump it up another notch, but be mindful of your top end...your RPMs will be higher on the top end the lower you go with your gearing. So if you do a lot of highway travel 4.56s might be more 'fuel efficient' for you than 4.88s.

This tool might be helpful in your decision making process: http://www.4lo.com/calc/geartire.php

If you're dead set on going the CAI route AND if you don't plan on serious off-roading, you could always replace the stock air box with a K&N and cut a section out of the hood directly above and mount a universal scoop to force outside air in. That would be better IMO than a snorkel...snorkels are worthless unless you plan on submerging your vehicle in water that can reach over the air box, and if you're in water that deep you better have a diesel or you'll have more worries than water in your intake.

These Landys, FJs, Jeeps, and whatnot that run around town with snorkels crack me up...99.5% of the snorkels I've seen were installed merely for show.

[LoJac963]

Right but the stock intake system draws air in from the fender which is cool air. Most systems just suck in hot air from the engine compartment.

I think the stock system is perfect which is why I went with a Volant box.

[ryaleon]

This is all great info. I will most likely regear. What do I need to know about this? Is it too much for a home mechanic to do? Where can I get parts?

[MVR 155]

Stock GM tuning leaves quite a bit on the table, I would love to tune my truck but I have a GMPP major guard for another 2.5 years that I don't want to be voided. Check out Nelson performance, highly recommended for GM trucks.

Another thing..... for the guys with the 2003-2007 trucks suggesting 4.88 gears..... The 08/09's stock have 3.73 gears vs. 4.10's that come in the 03-07's. That is a major jump in gearing for a tire that is only about 2 inches taller and will certainly have you turning some high RPM's on the highway. Going from a 3.73 to 4.88 will have you going from about 1700rpm on the highway to over 2200 (assuming approximately 75mph). The 6L80 also has a very steep first gear ratio of 4.027 which could make for some jerky driving at low speeds. Before jumping up that much I would see if you could talk to someone who has done this in a 08+ truck.

[KT2T]

Originally Posted by MVR 155

Another thing..... for the guys with the 2003-2007 trucks suggesting 4.88 gears..... The 08/09's stock have 3.73 gears vs. 4.10's that come in the 03-07's.

I went looking for this information before MVR 155 posted the above and found this:

http://www.vibratesoftware.com/html_...MER/Hummer.htm

On that page, it lists 2003-2008 with 4.10 but that the 2008 optionally has 3.73. If this is the case, how would a second-hand owner of a 2008 validate what's already in the truck to determine what gearing to move to? I have also put 37x13.50 Interco SS M16 on my truck and have been thinking about re-gearing (thus my interest in this thread).

[guruerror]

Originally Posted by ryaleon

This is all great info. I will most likely regear. What do I need to know about this? Is it too much for a home mechanic to do? Where can I get parts?

I got mine at Trail Duty: https://www.trailduty.com/index.php?...c27c864fc4998f

You'll need the fronts, rears, and an install kit.

It's hard for me to comment on the install since I had the shop do mine, but I think if I had the 'time' on my hands and knew that I had the appropriate 'tools' that I could have done them; there doesn't seem to be anything obvious that jumps out at me as being super difficult. Surf YouTube for instructional vids on swapping gears in a H2/2500 4WD or similar...that should give you a better idea.

Originally Posted by MVR 155

Stock GM tuning leaves quite a bit on the table, I would love to tune my truck but I have a GMPP major guard for another 2.5 years that I don't want to be voided. Check out Nelson performance, highly recommended for GM trucks.

Another thing..... for the guys with the 2003-2007 trucks suggesting 4.88 gears..... The 08/09's stock have 3.73 gears vs. 4.10's that come in the 03-07's. That is a major jump in gearing for a tire that is only about 2 inches taller and will certainly have you turning some high RPM's on the highway. Going from a 3.73 to 4.88 will have you going from about 1700rpm on the highway to over 2200 (assuming approximately 75mph). The 6L80 also has a very steep first gear ratio of 4.027 which could make for some jerky driving at low speeds. Before jumping up that much I would see if you could talk to someone who has done this in a 08+ truck.

Which is why I recommended the gear calculator (http://www.4lo.com/calc/geartire.php) it'll let him compare various combinations to stay with a stock final ratio and keep the truck in it's powerband.

[ryaleon]

Seems I would be better off with 4.56 vs the 4.88. 4.88 seems like a huge jump from 3.73.