LLY to LBZ Conversion Complete

A_T_Ver

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Jul 31, 2007
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so this is a complete swap with new harness'es or the existing and replacing the trans as well or just putting a new valve body in the 5speed to get the 6th gear?

You'll have to have the 6 speed TCM along with the valve body for it to work in the 5 speed. From what i read the suncoast 6th gear kit comes with a locked TCM, that sucks. The money isn't worth the extra gear IMO.
Is the added benefit going from LLY to LBZ just so you can fuel higher?
 

McRat

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Aug 2, 2006
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LLYs are slow.

The LBZ Bosch elektr0nikz make more p0wer!

I'm not so sure yet.

We ran at full power at 5250rpm with LLY stuff, and similiar with LBZ. EGT's climb rapidly after 4000, and it takes pretty big turbos to make hardcore power up there. GT45 or larger.

The only reason we swapped to LBZ, is because of limitations using the existing 6-sp Allison conversion. It just wasn't working reliably. If we could have gotten a functional 6-sp conversion we would have remained LLY.

You might have to switch instrument cluster if you want tap shift display, and you must use the LBZ alternator IIRC.
 

RENODMAX

Dead Wrong
Mar 4, 2008
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This is a smart man, right here.:thumb:

But seriously, I don't get the whole convert one duramax to another duramax thing.

What's the point? :confused:

I could buy a complete motor for a little more than the cost of new injectors. Then I have a spare on the stand. And it'd probably take me almost equal time swapping motors as it would to do injectors on mine. What's not to get about that?
 

Brayden

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Jan 16, 2008
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I'm not so sure yet.

We ran at full power at 5250rpm with LLY stuff, and similiar with LBZ. EGT's climb rapidly after 4000, and it takes pretty big turbos to make hardcore power up there. GT45 or larger.

The only reason we swapped to LBZ, is because of limitations using the existing 6-sp Allison conversion. It just wasn't working reliably. If we could have gotten a functional 6-sp conversion we would have remained LLY.

You might have to switch instrument cluster if you want tap shift display, and you must use the LBZ alternator IIRC.

It takes some large injectors to fuel at high rpm correctly as well.
 

McRat

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Aug 2, 2006
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stock injectors at like 4100us and 38* timing works fine. :D

IIRC, 2500msec on stock LLY sticks went through the lights in 4th gear at 126mph on 28" tall tires. Log said 5250, but it never did bottom out.

Timing? As much as can be programmed without bursting. Keeps the pistons from cracking according to Mythbusters...
 

Cougar281

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Sep 11, 2006
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There aren't that many wires that need to be changed as Ben pointed out; When I was comparing, I found the TCM power was not in the same place on teh 06 UBEC connector as it was on the 04, and the few wires that need to be added/moved on the C100. Other than that, the harness is PnP.
 

Brayden

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Yep...

I thought about making up a couple of jumper harness' that would repin C100 without having the end user having to have the terminals and crimpers..

I have a couple of pulling trucks to convert and it'll make it easier.
 
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DIESELMAFIAPER.LB7

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You'll have to have the 6 speed TCM along with the valve body for it to work in the 5 speed. From what i read the suncoast 6th gear kit comes with a locked TCM, that sucks. The money isn't worth the extra gear IMO.
Is the added benefit going from LLY to LBZ just so you can fuel higher?

ya read bout the kit wish they would send it out unlocked so one could mess with the shift pionts an defuel but cant have it all right:confused:
 

TheBac

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Hmmm...it'd be interesting to adapt LBZ heads onto an LB7? Possible? If its not incredibly expensive to pull off, it could be another option for LB7 guys with injector issues.

x2 what Lennart asked....is it possible to use the 5 speed? If so, how?
 
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Cougar281

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Sep 11, 2006
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Could I use the 6-speed TCM with my 5-speed Alli and just program the TCM to never shift into 6th?

Yes and no... You'd need to swap the 6-speed Valve Body, NSBU and harness into the transmission. The solenoids (primarily the Trim & TCC solenoids) are different between the 01-05 5 speed & 06+ 6 speeds. I'm fighting that right now, but in reverse. I'm going to be swapping a LBZ into my truck, and already have the 6-speed VB in the transmission (It's actually a complete 6-speed trans), and the TCM doesn't like to play nice with the trim solenoids, primarily on the 2-3 & 4-5 shifts. Everything was perfect on it when I had the 5-speed VB in, but once I put the 6-speed one in, it got stupid.

Hmmm...it'd be interesting to adapt LBZ heads onto an LB7? Possible? If its not incredibly expensive to pull off, it could be another option for LB7 guys with injector issues.

x2 what Lennart asked....is it possible to use the 5 speed? If so, how?

Aside from the piston issues, you'd probably be better dropping a complete motor in (that's what I'll be doing). I'm pretty sure the reluctor wheel on the LBZ's is different from the one on the LB7 & LLY's, so it wouldn't quite be pull LB7 heads and install LBZ heads. LBZ blocks are supposedly stronger too. If it's a 2003 or newer (I know yours is Tom ;)), I don't think it would really that much more expensive than a simple motor swap. Figure get LBZ motor, wire harness for the body/ECM/TCM/Transmission, ECM & TCM and drop it all in.

You might have to switch instrument cluster if you want tap shift display Correct, and you must use the LBZ alternator IIRC.LBZ & LLY alts apear to be the same (they both have the same plug). LMM's have different plug, I believe.
 
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TheBac

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Ah yeah...forgot about the reluctor wheel. That kind of throws that idea in the can.
 

Chevyscout

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Apr 3, 2012
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I am wondering why I can't use the the motor wiring harnes on the lbz and it not work with ecm and tcm? I know that the pump has higher pressure, injectors have 7 holes, compresion droped..... But, (This is what I think)the ecm is still just tells the pump to pump, the injectors to fire, when and how long. I know that it monitors rail pressure. ?????

Back story:
I am in the middle of swaping motors in a 2004.5 LLY. I Bought a truck with a bad motor and found a good deal on a motor. When I called the guy he was sure that it was an 8th digit vin #2(which I now know that you have to look at another vin# also). I got there and the intake tube was different. He said that it was just a difference in emmisions and if it didn't work he would find the right one(this place had hundreds of motors). I didn't know better. I've learned a lot in 2 weeks. Almost everything that I've learned about the LBZ makes me want to try to make it work if not too difficult. But, I do have the option of trading it for an LLY.

By the way, I would be using the LLY turbo. It didn't come with the LBZ.
 

turbo_bu

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Mar 27, 2007
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Aside from the piston issues, you'd probably be better dropping a complete motor in (that's what I'll be doing). I'm pretty sure the reluctor wheel on the LBZ's is different from the one on the LB7 & LLY's, so it wouldn't quite be pull LB7 heads and install LBZ heads.


From what I have read, there are two reluctor wheel styles. The LB7 and LLY's use one style. And the LBZ's and LMM's use a different reluctor wheel.