Why the hard feelings about the 6.0 Chevy?

SoCalDesertRider wrote:
Sounds like you just need some lower axle gearing in your 6.0 Suburban to give it that extra oomph that you're looking for.

In the good old days, long before there were diesels in pickups, we had big block gas engines and low ratio gearing and we accomplished the same tasks that diesels do now. :)

Upgrade to gears in the 4.xx range for greater towing and braking performance and general pep around town.

These new generation gas engines are built to rev high, with very high rpm torque and horsepower peaks. They need low gearing to get them up into their power bands.

Transmissions these days have plenty high overdrive ratios, so the engine will still cruise at a low rpm at freeway speeds and shift out of overdrive on the hills or for passing.

It's not like in the olden days when if you geared the truck to pull, you had to be relegated to the slow lane on the freeway even when unloaded, because the revs were too high, because transmissions didn't have overdrive back then.

Now we have even double overdrive on alot of these new trannys. All the more reason to gear the truck down and take advantage of greater torque multiplication at the axle, while still being able to drive 75mph on the freeway with that extra 6th gear OD.

I changed from 3.55 highway gears to 4.56 towing gears in my gas engine F350 and it made a world of difference in towing, hauling, mountain driving and general around town pep as well. The gears gave the truck that extra power that the small gas engine just couldn't put out.

This is 100% correct and will definitely be one of the things I do to improve the truck. With the tire size I run (tall 33's) I'm highly considering just going up to 4.56 gearing.

My ONLY issue is with my transmission as there is not a 1:1 direct ratio in the 6L90E. 4th gear, which is usually direct in most other 5 speed or greater OD transmissions, is actually a 1:1.15 in mine. Not much different than 1:1 but I don't ever get the direct ratio and 1:1 full 3.73 gearing effect. Basically it makes it a little more difficult to find a "sweet spot". I would like it to kick down from 5th as needed to keep highway speed but in mine, kicking down to 4th revs it up more than needs IMO.

IE, rear gearing and tires the same at 3.73/33", the 4spd 4L80E goes from 1850rpms at 65mph in OD to 2450rpms in 4th (direct). Mine will go from 2100rpms in 5thOD at 65mph to 2850rpms in 4th at same speed. Its quite a difference. 2400-2500rpms is actually a pretty sweet spot for the 6.0L from my experience.

This kinda makes it hard to choose the gearing I want because towing in 4th is kinda silly and since I usually tow in 5th at 0.85:1 ratio I have to make sure to choose gearing for the cruising speed and RPMs I want to be for best performance.

I would LOVE to have a 4.27 gear option but no one makes it. That is actually the optimal gearing from all the calculators I've found. 4.56 in my application puts me close to what a stock 2500HD with 4.10 gear and the 4L80E transmission runs at if I decide to tow in 6th. It always seemed like a good combo so that's what I'm aiming for. It does open up more available gearing since I won't have to limit myself to 5 gears.