Best Duramax engine model for performance - Chevy and GMC Duramax Diesel Forum
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post #1 of 14 (permalink) Old 06-19-2019, 12:43 PM Thread Starter
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Best Duramax engine model for performance

I have a chance to purchase a LMM or an LB7 motor with approximately 120K miles on each. The LB7 needs to injectors, but I would plan to replace the injectors anyways. As for performance stock with EFI Live Tuning and aftermarket bolt ons with EFI Live Tuning, which engine does everyone think would be a better option. This motor will be placed in a car. I would like to place twinís, and maybe in S480 for the big turbo. Thatís what I had in my truck many years ago, and that thing screamed. Thoughts?
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post #2 of 14 (permalink) Old 06-19-2019, 01:48 PM
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Originally Posted by CamaroDMax View Post
I have a chance to purchase a LMM or an LB7 motor with approximately 120K miles on each. The LB7 needs to injectors, but I would plan to replace the injectors anyways. As for performance stock with EFI Live Tuning and aftermarket bolt ons with EFI Live Tuning, which engine does everyone think would be a better option. This motor will be placed in a car. I would like to place twin’s, and maybe in S480 for the big turbo. That’s what I had in my truck many years ago, and that thing screamed. Thoughts?

Honestly, which ever you get the better deal on would work if everything else is the same, the power output post tune, with the same turbos is going to be more or less the same. The LMM is easier to change injectors on and does not have the same head gasket issues as the early LB7. The factory turbo, if you would be using that on the LB7 is fixed with a wastegate and the LMM is a variable geometry turbo, so spool is faster but more moving parts. The LB7 is considered by many to be a stronger engine though in therms of the pistons and rods, so if you do not want to get into the bottom end the LB7 can theoretically take more power before you shorten a rod or crack a piston, though if your making this kind of power you should really build the bottom end anyway. the LMM will run higher slightly fuel rail pressure as well, but again, after turning and supporting mods, the blocks are pretty similar in performance so if one is significantly cheaper than the other, get that, if you want power without a bottom end, the LB7 is probably a slightly better option, If you want ease of future repair, the LMM is probably a slightly better choice. Given its going in a car with a huge engine bay though, im not sure the LB7 would really be too much harder to work on, though there is a good bit more disassembly required to R&R the injectors. Lastly, the LB7 (if its federal, which most are) will have 0 emissions equipment on it, so that might play into your decision if you dont want to get / fabricate the extra hardware to delete the LMM, since im assuming you dont plan to run a DPF under your Camaro.

2015 Chevy Silverado 2500 HD 6.6L LML
TCM & ECM Tuning by MotorOps
Y Bridge delete with SS up and down pipes
4" MBRP downpipe back exhaust with muffler

Last edited by J83; 06-19-2019 at 01:51 PM.
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post #3 of 14 (permalink) Old 06-19-2019, 01:57 PM Thread Starter
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Thanks for the response back. The LB7 needs new injector. The guy is asking $2500 for it. This engine has 117K miles on it. The LMM has 135K miles and the guy is asking $4k. The LMM has no issues with it. For the LB7, I could replace the head gaskets and injectors before I install it into the car.
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post #4 of 14 (permalink) Old 06-19-2019, 02:50 PM
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Originally Posted by CamaroDMax View Post
Thanks for the response back. The LB7 needs new injector. The guy is asking $2500 for it. This engine has 117K miles on it. The LMM has 135K miles and the guy is asking $4k. The LMM has no issues with it. For the LB7, I could replace the head gaskets and injectors before I install it into the car.
after the cost of the injectors, install kit and new gaskets the LMM is almost certainly cheaper, and that doesent include your time. Also, R&R on an LB7 requires a significant teardown compared to the LMM. i did a quick search for a used LB7 engine, and theres running engines under 4K. Your cost for the injectors and hardware is going to be 2-3K, so unless the seller wants to come down on that price id go with the LMM, that is unless of course you plan to put bigger injectors in regardless of the engine you pick, but id still ask for them to come down on the price.

2015 Chevy Silverado 2500 HD 6.6L LML
TCM & ECM Tuning by MotorOps
Y Bridge delete with SS up and down pipes
4" MBRP downpipe back exhaust with muffler

Last edited by J83; 06-19-2019 at 02:56 PM.
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post #5 of 14 (permalink) Old 06-19-2019, 04:46 PM Thread Starter
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Iím planning to put 60% over injectors. If I go with the lb7 I would do it immediately. As for the lmm, I would run it stock for a while. Yes I think I will offer him significantly less and see if he bites. I also need to find out if he will let the ecm go with it. As for the vvt, I will be looking to replace it with an s366. These power modifications will depend on the cost of the car when the times comes.
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post #6 of 14 (permalink) Old 06-19-2019, 07:26 PM
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where are you located?

2002 GMC 2500HD, ECSB, 4WD, LB7
new style gm exhaust manifold, banks big head wastegate, PPE boost valve, banks air intake,high idle switch in cruise control, stock but not for long
EFI live tuned by me now,dps5 switch,EGT probe and autometer boost sensor,SoCal 6spd conversion

2016 GMC Denali stock for now
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post #7 of 14 (permalink) Old 06-19-2019, 08:36 PM Thread Starter
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I’m in Colorado.
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post #8 of 14 (permalink) Old 06-20-2019, 03:55 AM
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to bad your not closer,have a basically new lb7/lly headed(ported) engine w/ a 366 turbo on it.

2002 GMC 2500HD, ECSB, 4WD, LB7
new style gm exhaust manifold, banks big head wastegate, PPE boost valve, banks air intake,high idle switch in cruise control, stock but not for long
EFI live tuned by me now,dps5 switch,EGT probe and autometer boost sensor,SoCal 6spd conversion

2016 GMC Denali stock for now
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post #9 of 14 (permalink) Old 06-20-2019, 05:22 AM Thread Starter
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to bad your not closer,have a basically new lb7/lly headed(ported) engine w/ a 366 turbo on it.
Just curious, where are you located at? Is the engine built or stock internals?

Thanks,
Joshua
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post #10 of 14 (permalink) Old 06-20-2019, 10:55 AM Thread Starter
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Thanks for the information and support. I made an offer on the LMM and the guy accepted. Yippee!
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