LB7, LLY,or LBZ - Diesel Truck Forum - TheDieselGarage.com
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post #1 of 14 (permalink) Old 08-29-2007, 05:08 AM Thread Starter
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LB7, LLY,or LBZ

First post and I'm trying to learn. Which model Duramax LB7, LLY, or LBZ is "The Best" for a 600+hp build up and why?

I have been searching on here trying to find out as much as I can on each model engine and their differences....Blocks, Cranks, Pistons, Cams, Heads, Injectors, CP3's, Turbos, Auto trannies....and so on. Is there a Duramax Bible that would help me out in my research?

Brent.
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post #2 of 14 (permalink) Old 08-29-2007, 06:04 AM
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LB7 all the way baby. The reason being is that, you can find some without EGRs and they are simple to work With. Also the LB7 seems to have a lower piston failure rate than the LBZ. Also the 5 speed tranny is easier to work with.

2001 Chevy SB/CC Duramax LB7

Garrett GT4088R from PPE, PPE Duel fuelers, PPE Tuning, PPE stage 4 transmission w/suncoast 1056 converter, PPE Lift pump, Fabtech tie rods, Black Eagle alloys.
Engine is apart and in the garage
Goal is to have it done by the end of this summer.
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post #3 of 14 (permalink) Old 08-29-2007, 12:31 PM Thread Starter
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So the LB7 I guess has two versions? One with an EGR and one without? What exactly do you mean by the auto tranny is easier to work with?...Do you mean programming or are they a completely different allison.

I am looking to do a conversion, trans included, and I plan on going pretty wild with the engine...SO I'm wondering since pistons, rods and heads will be "built" does it really matter which model I go with? Sorry for the lack of knowledge...I learn fast though.

Brent.
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post #4 of 14 (permalink) Old 08-29-2007, 12:55 PM
 
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anytime you go over the 550 or 600rwhp level you will start spending big money to upgrade internals of th engine but your best bet is staying with the LLY or LB7..
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post #5 of 14 (permalink) Old 08-29-2007, 02:37 PM Thread Starter
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Thanks for the tip...But unfortunately I have learned that all to much by being in the PSD world for many years. With the PSD you spend 18k-20k to net you ~550-600hp/1200-1300tq... Also only have fuel to ~3500rpm's because the PSD's HEUI systems electronics can not fuel over that...and still end up spitting the crank out the bottom end because the stud and girdle kit doesn't cure a weak crank.

I don't mind spending money as long as the beast is going to hold together.

Now my memory isn't that good so...The LLY is the first gen and the LB7 is the second gen that the early versions of the LB7 are non EGR engines???

Does anyone know what the L, the L, and the Y stands for or the L, the B, and the 7 for that matter?

Thanks,
Brent.
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post #6 of 14 (permalink) Old 08-29-2007, 03:59 PM
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I'm no engineer and not a vendor. I'm just an enthusiast. Been reading the forums for a long time, and have been privileged to be friends to one of the leading Dmax guys in the country (Eric Merchant). I've learned a lot from people smarter than me, asked a LOT of questions, and had many people give me advice. ASked people at pulls and races what they've done, how things worked together, etc. Basically been a PITA, if you know what I mean. There is no real "bible" as many people have taken different routes to build big power. These are all things I've learned over the years. I hope other people chime in with their knowledge.

LB7, LLY and LBZ (and now LMM) are just the option codes GM used to denote the diesel. When GM changes a design (as they did in when the heads changed in 2004 on the LLY) they change the option code.

LB7, LLY are both pretty much the same short block. The block, pistons, rods, crank, etc are all the same (maybe some small variations, but nothing big)
The heads are different between the two. LB7 injectors are under the valve covers, while the newer LLYs had them accessible from the outside (hence the head redesign).
Only trouble is, LLYs were prone to overheating. Whether that is due to the head redesign, the programming change (GM upped the stock power 10hp), or just GM not updating the cooling system is a topic of much much discussion....very heated discussion.
The intakes were redesigned too, with LLY getting a larger main runner. I don't believe they can be interchanged, though.

California LB7s sometimes came with EGR. Some had them, some didn't. Federal emissions LB7s did not. IIRC, all LLYs had EGR systems. They can be defeated using whats called a "Fingerstick" to fool the computer combined with a blocker plate. EFI live can also turn the EGR off.

LBZs are a different story. GM updated a LOT of parts in them. Blocks got a beefier design, esp in the main webbing but dimensionally, the blocks are the same.. Pistons have lower compression (IIRC, it changed to 16.8:1 from 17.5:1), coated sides, and shorter skirts. They are a lighter design too. Rods were beefed up considerably and have a bushed pin end. I think the cranks are still the same as the LB7/LLY. Cooling systems were upgraded (water pump is definitely different...bigger impeller and outlet), as were the intake systems. I know there were other subtle changes, too...but cant remember them all. I do not think the heads were redesigned again, but I may be wrong about that. I know Merchant would have that information.

LBZ's have EGR, too but that also can be defeated. Tuning is different, too.
LMMs are LBZ's with a boatload of emissions crap on them, and different tuning.

Concerning the Allison, MikeL and Merchant know FAR more than I do. I've seen the insides of quite a few Alli's, and had Merchant walk me through my own build, but a lot of it was wayyy over my head. Just was never Alli-literate, I guess.
IIRC, the LB7 Allison and the LLY version are pretty much the same. There might be some subtle differences, but you got me what they are. I do know that you can use them with either engine, so it just may be a TCM change.

LBZ Allisons are 6 speeds, and have many of the physical upgrades that were pioneered by Suncoast and MikeL. This was done to handle the extra 50hp the LBZ puts out.

For any Allison to hold BIG power you still have to adhere to all the rest of the upgrading rules, same as the 5 speed -- they both need a new converter w/billet cover, better clutches, etc...
Also, the TCMs in the 6 speeds are different, and due to the diligence of some VERY intelligent Dmax'ers out there (Hi BEN!), it is possible to retrofit them into the older trucks. Suncoast even sells a kit to add 6th gear into the 5 speeds (they have the gearing, its just not activated)

----------------------------------------------------------------------

500rwhp is relatively easy to do on stock parts. The engines hold that power relatively well. Big tuner, Trans, Exhaust and you're there. Thats where I am.
There are some people out there that have been running 450-500 hp for a lot of miles with no trouble.

Over 500rwhp is another story. There are LOTS of parts available to build a wild and crazy engine, but you HAVE to build the low end first, and its not cheap!
Just a list off the top of my head of what's available:

Heads:
ported/polished
Custom larger valves, stronger springs, solid retainers
Custom billet valve bridges/injector clamps
Larger injectors ( I think they can get up to 100% overs...)
There are cams available that are matched to the custom heads, and also a rev kit has been developed for the Dmax for higher-rpm apps.

There are head stud kits available from ARP, and they also have main stud kits and even injector hold-down stud kits now. So you're covered there.

Blocks seem to be holding up ok. As stated before, the LBZ block has beefier main webbing. There has been some talk of new billet maincaps, but god, there'd be some incredible expense there. Studding the mains seems to work fine.

Cranks haven't been improved upon yet, but if Nasty is using a stock crank, then I guess they're good to 1000hp. Same for the block.

You can cut the stock LB7 pistons down to lower CR, and can even have them coated. The LB7 piston design is heavier than the LBZ. There is a LOT of controversy over which design is better. Because its all so new, nobody really knows yet. Testing has been underway for a while now.
There are also forged pistons available from Ross. I think Mahle was going to introduce a forged piston, but not sure if thats available now.

Please, for your own sake, don't use stock rods in anything over 600hp. Crower and Carrillo both makes rods for the Dmax. THEY ARE NOT CHEAP! Be prepared to spend $2500. But, its a must. Hopefully, someone out there will figure out a way to bring those costs down.

Oiling system seems to work fine even at higher power levels. I remember someone dissecting a pump to see if there was more flow potential, but I do not know if anything ever came of it.

Fueling systems can get outrageous. Dual CP3's, lift pumps, billet pickups are all available from many different Mfgs.

Turbos? Man, the list is soooo long. You can get big singles (aurora 5000, BD, garrett GT40 and GT42, PPE come to mind) or go twins (maximizedperformance (Nathan) is the only guy building them that I know of -- beautiful work) There seems to be a constant quest for turbos that light at lower rpm but flow at higher rpm...its just never ending.

Then there's the guys out there that are building headers and solid uppipes for these engines. Lots of other specialized parts being thought up every day. Theres even a spool kit available for the G80 posi rear now.

As for tuning, there are companies out there that use EFI Live to build tunes that make HUGE power. Ridgerunner Diesel specializes in LB7 tuning, and Mcrat racing is big for LLYs. I honestly dont know who the great tuners are for the LBZ.
Bottom line, though, is that to make big power, you have to use EFILive. IIRC, there are no "company" tuners out there that can support that much HP.





As long as you build the bottom end first, you can go wild with any of the Dmax versions. I guess my advice would be to find a wrecked truck and go from there. Give Merchant a call (look in our Vendor section) and ask his advice...he's built more Dmax's than most people, and knows all their ins-and-outs.. Call McRat (Pat) and ask him for advice....he has the fastest LLY on fuel in the nation.

Like I said, I'm no expert. I've gleaned a lot of info from the forums over the past 4 years. It has helped me decide what I've wanted to do with my truck.
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post #7 of 14 (permalink) Old 08-30-2007, 02:56 AM
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Nice post Tom. I might have to plagiarize it.

Michael
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post #8 of 14 (permalink) Old 08-30-2007, 03:32 AM
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I just started typing, Michael....and ended up with that. I can't believe Dmax performance has come so far, so fast. It's amazing.
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post #9 of 14 (permalink) Old 08-30-2007, 03:56 AM
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is there something wrong with the forum tonight? I can't start a new thread.

Michael
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04.5 GMC 2500HD SRW LLY

Learn about INDUCTION OVERHEATING


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post #10 of 14 (permalink) Old 08-30-2007, 04:07 AM Thread Starter
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MAN! I really appreciate all the info....Exactly what I was looking for!

You mentioned alot of things but for now two things bring me to more questions...The aftermarket billet rods that are available...Are they heavy to the point where the crank needs a crap load of holes drilled into it?

Also...With the LBZ having a beefier block would an LBZ block and crank, with LB7 heads, billet rods, forged pistons and such work out?

In the PSD world one brand of the billet rods available are really heavy and after ballancing is done some have said their cranks look like swiss cheese...Some say it is good having more rotating mass and others say to lighten up the mass for longevity and rpm's. I guess it's alot like the overheating discussions with the D-max

Brent.
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