Went fishing with the beast last weekend and managed 16.8 mpg. Considering the tune still has room for more mpg, I was in the Uintas (10,000'), drove on a dirt road/ trail for 20-30 miles of my trip, and climbed up/ down from my 5,500' starting altitude... I'd say that's not too bad.

With the bigger tires this thing loves the country roads at around 55-65mph. Pulled the hills fine on the way up there and even pulled Parlys no problem. I actually pulled the last hard climb up Parlys so well, I didn't really notice it. Just dropped in 3rd and cruised up around 65-70 without pushing it. Temperature seemed fine and didn't climb noticeably the whole day. The fusion dual electric fan setup is working well.

The only real downfall of this setup on hills is that it really could use an extra gear or two. A 5 speed manual or an auto with 5-6 gears would make it handle less like a muscle car and more like a modern vehicle. I still need to drive it like an enthusiast. Dropping a gear manually to pull a hill instead of waiting for the trans to do it and then hunt around.
I have few complaints and I think with more tuning I could get 18mpg with the right driving style. That's getting into the same territory as my wife's Lexus GX460 with a 6 speed auto!

Summary: works well, fun, a worthy upgrade, a 5speed manual or 6 speed auto would make the powertrain awesome (and leave room for power adders... Think of 450hp with 1-2 more gears. Sounds fun)

 

Nice pictures! That is great mpg, especially considering the elevation, terrain, and tires. And if you think you can get more mileage out of it, even better still.

I think you might find that you get significantly more towards what you are looking for by adding a Compushift. I’m planning on going that direction as well very soon. It requires an extra interface box to keep all the factory stuff working with ACE stuff and Rover stuff but allows for full transmission shift mapping so you can dial it in exactly as you want.

Can also dial up the shift pressures, so should be able to push a bit more power through transmission as well. I know of a guy using a 5.7 LS1 with it.

 

I'll have to wait for your review. That price is a little salty. I think it would be nice, but ultimately more gears are why I'm thinking I need eventually. Big plans and struggles on the home front in the next year so I don't anticipate many $1k purchases soon for something that isn't broken. Well broken yet.

 

That's some great mpg. I'm only seeing 12.5 mpg mixed but I'm on 35" mud terrains, 4.43 gears, metal front bumper/winch, roof rack, lights. At 70 mph I'm at about 2600 rpms (5.3 L33 with btr truck Norris cam)

 

if you run a 6L80 or 6L90 with a 3rd gen motor you'll need the compushift regardless. That said I still think that's the way to go if undergoing the swap. If you get the gearing right in the t-case and diffs in low those first two gears get you almost to crawlbox territory ratio wise which if you wheel would be amazing. Considering an ashcroft underdrive is unobtainium at this point and will cost far more than the added cost of the compushift and LT230 adapter plate to run the 6L80/90.

 

Yes I would need a TCU. I found some that impressed me more than the compushift that were available for the 6l trans though. I just don't know if the money into the current trans setup is what I'm thinking or save for another TCU and trans.
After more research if I determine the compushift is the best 6l TCU then maybe I'll upgrade the ZF, but if it's not the best 6l TCU then I'd rather save 1/3rd the trans upgrade cost for a future shoehorn.

 

What does your wideband show when driving? What fuel? I'm running our premium which is 91 with "up to 10% ethanol". 2600 at 70 doesn't sound far from what I'm pulling.

Oh and is your truck tuned?

 

After driving some more today I think I'm ready to declare our RPMs at cruising speed the biggest issue. Surprise surprise. I'm turning around 2600 at 77-78mph and driving around 2500rpm on the highway I only get maybe 13-14mpg. If I can keep that number closer to 2000rpm I think I can replicate my 16+mpg. More gears, less rpm, or if I can get lean cruise to work. I've tried a couple times and I'm running out of things to try unless I can find a bin file from a Holden or whatever that came with lean cruise. The issue with that is I'm doing segment swaps (which I haven't done yet), or copying every parameter I can think to change to match the 5.3 and hoping I get lucky.

Time for me to research segment swaps and get some support from pcm hackers.

 

You're absolutely right about the rpms. I just recalculated on my drive to work today at a cruising rpm of 2500 (65 mph) and got 14 mpg. That's on 4.43 gears and 35" MT. I wish I would have gone with 4.11s now that I have an LS swap.

 

Don't feel too bad. I with I had 34" tires to lower my cruising rpm more haha. I would have gone bigger than 32.5", but I wasn't sure if would fit in the garage. To be honest, with fresh front springs I'd probably be close to not fitting. Hell I'd probably gain 1/2" of height with shocks that are actually charged.

I got lean cruise to work this morning. I was groggy and didn't even expect it to work. I was cruising at 50 and out of the corner of my eye I see my wideband go red... That's weird. I see it hit 15...16...17... Wow it works! Maybe a little aggressive, but it's a start. Probably a good thing it didn't work on the highway with how mean it was. I changed the params a bit and hopefully it will get a little closer to 15-16. I'll definitely be logging on my drive home today to watch for knock. It's promising though. Crazy how it's cruising at high 16:1 afr and it sounded completely normal and felt normal. I wouldn't have known it worked without my wideband.

PSA: Doing something not stock with your engine? Get a wideband. It's crazy how much insight you can instantly get from seeing your afr.