LBZ cracked piston - What long block to with ?

OleBlackyLBZ

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May 22, 2020
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If you get pistons out of a truck from a LLY/LB7 (I guess if you even get them from gm they come in an isuzu box and are standard bore or .050 over last I checked) they are decent and will handle some power

Pistons you get directly from Mahle the LB7/LLY OE replacement are trash

The mahle motorsports Pistons are a decent option.
That's good to know, I did not realize there was a difference in the mahle replacement and mahle motorsport race cast. Thanks for clearing that up for me..
 

OleBlackyLBZ

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That's awesome.. if you ever use in the range of 700-1,000 hp I'm very impressed with those pistons(I know some people drive easy). I'm around 675 on de-lipped lb7's but I mostly drive it on a 590ish hp tune. How do you think I will fair? I drive pretty hard but like I said I'm just a tad under 600 most times
 

Bdsankey

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That's awesome.. if you ever use in the range of 700-1,000 hp I'm very impressed with those pistons(I know some people drive easy). I'm around 675 on de-lipped lb7's but I mostly drive it on a 590ish hp tune. How do you think I will fair? I drive pretty hard but like I said I'm just a tad under 600 most times
For the extra $300 buy the Motorsport piston.
 

OleBlackyLBZ

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May 22, 2020
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Too late, and that would have added $1650 to my $5900 longblock since the lb7 pistons were done there.
 

gmduramax

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That's awesome.. if you ever use in the range of 700-1,000 hp I'm very impressed with those pistons(I know some people drive easy). I'm around 675 on de-lipped lb7's but I mostly drive it on a 590ish hp tune. How do you think I will fair? I drive pretty hard but like I said I'm just a tad under 600 most times
Those will hold up just fine
 

OleBlackyLBZ

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Anthony I apologize if it seemed like I jumped you about the lb7 pistons. I didn't mean anything bad I just really thought you didn't know lol, I quickly realized you knew more than me but again I apologize if I came across wrong.
 

gmduramax

Shits broke
Jun 12, 2008
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Just to be clear, are you referencing the OEM style piston or the Motorsport?
The OG LLY/LB7 pistons hold up ok I wouldn’t run them over time with more than 800hp if I wanted them to last.

motorsports pistons seem to hold up to 1000hp well

I would not recommend (OEM) mahle pistons in anything.
 

gmduramax

Shits broke
Jun 12, 2008
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Anthony I apologize if it seemed like I jumped you about the lb7 pistons. I didn't mean anything bad I just really thought you didn't know lol, I quickly realized you knew more than me but again I apologize if I came across wrong.
No worries at all. We’re all here to learn.
 

rcr1978

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Apr 1, 2007
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Well I didn't have any troubles ruining stock LB7 pistons under 70k with a max effort stock turbo/fuel truck= 500ish hp and it didn't get beat on to hard I towed with about 375-400ish hp. So if those Mahle stock replacements are worse I would be nervous.
 

Chevy1925

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Delipping is the key to getting lb7/lly to hold up to the higher hp level. They can be pushed farther if you run more air than fuel to achieve power, run a large injector to keep uS very low, and good tuning.

Coating them use to be thought that it helped, all it did was burn up inside and did nothing to protect the pistons
 
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Bdsankey

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Delipping is the key to getting lb7/lly to hold up to the higher hp level. They can be pushed farther if you run more air than fuel to achieve power, run a large injector to keep uS very low, and good tuning.

Coating them use to be thought that it helped, all it did was burn up inside and did nothing to protect the pistons
The question here is was that due to inferior coating technology at the time? I know many engine builders seem to be using Polyphen from Techline these days. The price on coating my motorsport pistons was too low to pass up so I figured I might as well try this for myself so I can actually weigh in on this topic.
 

OleBlackyLBZ

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Ya I would be interested to see if say after 50K miles of abuse if the coating would still be on the piston. I didn't have mine coated because I was unsure about it at the time. Kinda wish I'd tried it just to see like you said.
 

rcr1978

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What color is the polyphen coating? Im not sure what i got, industrial coated the pistons so who knows. Im betting its not on there anymore and probably didn't do the cylinders or ringseal any favors.
 

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Bdsankey

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What color is the polyphen coating? Im not sure what i got, industrial coated the pistons so who knows. Im betting its not on there anymore and probably didn't do the cylinders or ringseal any favors.
The coating that mine are being done in is Polyphen Gold (LINK). These aren't my pistons, this is a stock image off of Tech Line's website of pistons with their thermal barrier as well as their skirt coating.

1592402556021.png
 

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