Duramax block strength

JoshH

Daggum farm truck
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Feb 14, 2007
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Here's a pic of it
2b87e1901d47cc28f02b315ab883e288.jpg


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That's interesting looking. Thanks for sharing. This was with stock caps, no girdle, with main studs (not stock bolts)?

Thanks to everyone else who has contributed also. I honestly didn't think a Duramax block was even remotely in danger of damage at 1000 HP, but maybe things are a little more in jeopardy than I realized.
 

coker6365

Coker6303's ***** Daddy
Dec 4, 2011
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That's interesting looking. Thanks for sharing. This was with stock caps, no girdle, with main studs (not stock bolts)?

Thanks to everyone else who has contributed also. I honestly didn't think a Duramax block was even remotely in danger of damage at 1000 HP, but maybe things are a little more in jeopardy than I realized.
Poor Allen is probably losing sleep over this thread now.

Very interesting read. I guess a lot of this stuff stays hush hush.

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Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Poor Allen is probably losing sleep over this thread now.

Very interesting read. I guess a lot of this stuff stays hush hush.

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i wouldnt say hush hush, just not asked. as you can see, many people still will share their experience and fixes :D.

Now watch, everyone scared of breaking cranks are gunna freak out about blocks now :rofl:
 

coker6365

Coker6303's ***** Daddy
Dec 4, 2011
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i wouldnt say hush hush, just not asked. as you can see, many people still will share their experience and fixes :D.

Now watch, everyone scared of breaking cranks are gunna freak out about blocks now :rofl:

LOL, now that is no lie!!! Just went we thought the billet cranks were the end all, now we have block failures. :roflmao: On a serious note, I am not too worried about it. If it happens, so be it. There are plenty of weekend warriors running around with no problems. I would venture to say it is the die hard competition motors that see most of the failures being they are pushed to the max every time.

Now that I say that, I hope I am not the first to break a billet narrow rod crank from SoCal. :D If it does, Josh may be getting some built motor parts donated...
 

WolfLMM

Making Chips
Nov 21, 2006
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LOL, now that is no lie!!! Just went we thought the billet cranks were the end all, now we have block failures. :roflmao: On a serious note, I am not too worried about it. If it happens, so be it. There are plenty of weekend warriors running around with no problems. I would venture to say it is the die hard competition motors that see most of the failures being they are pushed to the max every time.

Now that I say that, I hope I am not the first to break a billet narrow rod crank from SoCal. :D If it does, Josh may be getting some built motor parts donated...

I'm right with you on that one. However I'll say I'm not in the least worried about my SoCal motor. I realize failures happen, but I did everything possible to mitigate that possibility.
 

bcdeutsch731

Member
Nov 4, 2010
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I've never split a block but I've done my fare share of damage to blocks. I've had a few built motors in my race truck. I think machine work and clearance have a big part in block strength and longevity.
I have mix feelings about half fill blocks. On one of my race engines that I got hot you could see right where the concrete ended in the cylinder. It put a wear mark right at that spot. The motor still ran fine but when I tore it down to do head gaskets you could see right where the concrete ended.

Wagler Competition machine work is top notch! As you go together with the motor everything spins so much better with less friction. Their clearances are spot on.
 

D1rty-max

Spare some change?
Jul 16, 2015
132
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Longview, TX
Must not be that big of an issue if we are just now talking about this. Maybe everyone should just start using an LBZ block instead of using the older LLY/LB7s :thumb:

LBZ changes according to GM-Cylinder block casting and machining changes strengthen the bottom of the cylinder bores to support increased horsepower and torque.

Maybe LB7/LLYs break more? Don't the LMLs have upgraded webbing to increase block rigidity even farther than the LBZ/LMMs?
 

duramaxzak

Wanna be puller!
Nov 22, 2008
2,431
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Minnesota
I built my LB7 motor with a LMM block in my pulling truck and have not have any issues yet and am on my 3rd summer pulling with it. It dynoed 1252hp at the wheels about 2 years ago with a Precision 3.0" single turbo and should be up about another 100hp since than. I had also heard the LBZ LMM blocks are a little stronger than the older ones.
 

JoshH

Daggum farm truck
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Feb 14, 2007
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Must not be that big of an issue if we are just now talking about this. Maybe everyone should just start using an LBZ block instead of using the older LLY/LB7s :thumb:

LBZ changes according to GM-Cylinder block casting and machining changes strengthen the bottom of the cylinder bores to support increased horsepower and torque.

Maybe LB7/LLYs break more? Don't the LMLs have upgraded webbing to increase block rigidity even farther than the LBZ/LMMs?

:roflmao: Sorry, I'm not laughing at you, but my friend really hates me right now.
 

coker6365

Coker6303's ***** Daddy
Dec 4, 2011
486
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:roflmao: Sorry, I'm not laughing at you, but my friend really hates me right now.

:stirthepot2: I am just stirring the pot since I am sure will have a failure before he will.

My luck is so bad, it could be raining women and a queer would fall on me! :roflmao: