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Online Flyin6

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Duramax discussion: LB7
« on: July 17, 2019, 04:27:02 PM »
So to start this off, we have discussed the possibility of replacing the 6.0 gas engine in my Suburban with a Duramax

TexasRedNeck suggests I start with a LLY cylinder head and injectors grafted onto a vintage LB7 block.

The LB7 places its injectors inside the valve cover, while the LLY places them outside in a configuration much more familiar to most D-Max owners

Given that my truck is a 2002, it would be easiest to just swap in an entire 2002 LB7 and Allison 5 speed drivetrain.

So, let me start this off by asking, why is it necessary to swap heads? Why not just work with the LB7 with upgraded and proven parts to achieve a high output LB7?
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Offline EL TATE

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Re: Duramax discussion: LB7
« Reply #1 on: July 17, 2019, 05:54:41 PM »
So to start this off, we have discussed the possibility of replacing the 6.0 gas engine in my Suburban with a Duramax

TexasRedNeck suggests I start with a LLY cylinder head and injectors grafted onto a vintage LB7 block.

The LB7 places its injectors inside the valve cover, while the LLY places them outside in a configuration much more familiar to most D-Max owners

Given that my truck is a 2002, it would be easiest to just swap in an entire 2002 LB7 and Allison 5 speed drivetrain.

So, let me start this off by asking, why is it necessary to swap heads? Why not just work with the LB7 with upgraded and proven parts to achieve a high output LB7?

Bad injectors/$$$ bad cp3/$$$ I don't know that there is a real world permanent solution to the LB7 injector issues to this day, I replaced two sets before my transfercase front end/rusty frame and yet a 3rd set of injectors prompted the sale of my 03. if you can overcome those two major hurdles then I don't see why it's not a viable option.
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Online Flyin6

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Re: Duramax discussion: LB7
« Reply #2 on: July 17, 2019, 08:51:55 PM »
One thing that is becoming a concern is the outrageous cost of prepping an engine, well just finding it and a transmission, then the rebuild costs place the benefits in serious question.
Rebuilding the bottom end and a valve job with good parts could easily get to 6K-7K without acquisition costs. Another 4.5-5.5K for a transmission and already we are over 10K by a bunch...
Now the LB7 cores I am finding are from $700-$1600 but the LLY and LBZ's run closer to $3K.
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Offline stlaser

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Re: Duramax discussion: LB7
« Reply #3 on: July 17, 2019, 09:37:38 PM »
Caddy 500 / nv4500 / np205 for the win!
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Offline rpar86

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Re: Duramax discussion: LB7
« Reply #4 on: July 17, 2019, 09:38:45 PM »
Tate, they have a new style of injector - SAC - that are supposed to be a lot better. You still have the issue of them being buried in the head, but if they last longer, then maybe it’s not so bad.

I’m not sure the cp3 is really that big of an issue. The head gaskets are another weak point - replace those with the newer style. But while you’re in there, might as well do the sportsman cp3 and be done with it. A lift pump for more filtration of course is a good idea too.


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Offline TexasRedNeck

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Duramax discussion: LB7
« Reply #5 on: July 18, 2019, 05:55:30 AM »
There are a lot of LB7s that have gone 300k. Most on a couple of sets of injectors.  CP3 is fine and head gaskets aren’t the best if you start increasing cylinder pressures (tune and turbo). Everyone moves to the newer gaskets when building. (The “C” gaskets IIRC)

SAC injectors may be the answer but given the labor costs to replace injectors when they are under the valve covers, if you are starting from scratch it’s easier and cheaper to run the LLY heads where injectors are not known to be a problem.

Yes you will easily be in the 10k range in parts alone. My transmission was $6k installed all by itself.

But in the end you have a lifetime vehicle and for much less than the $70-$80k for a brand new gas burb


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« Last Edit: July 18, 2019, 05:56:26 AM by TexasRedNeck »
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Offline rpar86

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Re: Duramax discussion: LB7
« Reply #7 on: July 18, 2019, 11:04:50 AM »
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Offline JR

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Re: Duramax discussion: LB7
« Reply #8 on: July 20, 2019, 08:54:23 PM »
Aren't the internals better on the 06 up motors as well as the Allison? Better oil spraying, stronger trans and the 6s?

I think up to 2010 the frame is the same so the swap will all be the swap. You need all new wiring anyway so the year should be mute.
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