What is the main difference between the LLY and LB7. Is it basically the same engine. I the MPG not as good on the new LLY? Thanks For any help?

There are some pretty good differances, and some not so good. The good is basicly moving the injectors to the outside of the valve cover. The bad was the implement of the emmisions stuff. Fuel mileage apears to be down about 25%. Low end power seams to be up slightly.

Need only do a search, tons of threads on this.. here is one of many

http://dieselplace.com/forum/showthread.php?t=20035&highlight=difference+lly+lb7

My 04 LB7 got about 21 mpg running about my daily business and my 05 LLY only 17 driving the same. The LB7 had more power too.

I would have to say that the mileage on my lb7 was 2-3 mpg better than my lly....but.............I would also have to say that I have more power with my lly than with my lb7. I guess there had to be atrde off somewhere. I still have hope that mpg will improve as I get more miles on my truck. IIRC the mileage on my lb7 was not very good when it was new either.

My first tank of fuel in my 2001 D/A was 19. I have two 2004.5' with over 170,000 miles combined, and they have never hit 19 to speak of. I don't know that more miles is helping. Everybody wishes for this, but I have not seen it in 5 trucks.

On my Trip to Suncoast driving both trucks from ATL to FWB the LB7 got 19.7 HWY and 16.4 around town while I was in FWB for the week.

The LLY got 20.8 HWY and 16.7 around town. I have been happy with the LLY mileage to date.

My 04 LB7 got about 21 mpg running about my daily business and my 05 LLY only 17 driving the same. The LB7 had more power too.

I agree, I have the same PROBLEM. And I consider it a PROBLEM. What a crock of horse Scheit GM has sold us. More power? NO Better Mileage? NO

Keep your LB7 ! You will get more power and better fuel economy, especially towing.

i don't know my stepdad bought an 04.5 and when he did this i bought his 02 and the only difference is that the 04.5 is a shortbed. everything else the same and he got 14 with the LB7 and he gets 13 with the LLY. but when he does pull his backhoe it drops alot more than the LB7 did but it pulls like a SOB. hes in the construction, always pulling some sort of trailer and has one of those big toolboxes full of tools. he loves the new motor, says more power pulling and runs a whole lot better then the LB7, but wants his mileage back.

BMDMAX, how long did it take for your LLY to start getting 20.8 MPG on the HWY? Whats your average speed on the HWY? Thanks

BMDMAX, how long did it take for your LLY to start getting 20.8 MPG on the HWY? Whats your average speed on the HWY? Thanks

It did that with about 2,500 miles on the ticker. We were running 80 on the Interstate sections of the trip and 65 to 72 for the remainder of the four lanes along the way. The speed limits run 55 to 70 depending on what section of road we were on and we held 10 over most of the time.