Which pistons should I use?
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
The reason most people have problems with hyper pistons is they require a wider piston ring gap and people don't check for that or think they can get away with tighter. They end up lifting ring lands.
Mike
Mike
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Jebby
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
"Special cast pistons were developed for the LS7, which feature an anti-friction skirt coating, anodized ring lands, improving hardness and wear resistance. Larger-bore pistons are by nature heavier than their smaller-bore counterparts, and here the LS7 design team countered this tendency by moving the pin bosses inward and employing a shorter high-strength full-floating piston pin. This approach yields a piston assembly that is lighter, while the shorter pin represents a mechanically stiffer arrangement. With a flat-top design, the pistons deliver a compression ratio of 11:1. The mechanical line-up downstairs makes it abundantly clear that this mill was designed from the ground up to turn a number."
I plan on fixing my 2010 C6Z06 (3,800 miles and no problems yet but not waiting...) heads myself this summer from these guys with Moldstar 90 guides installed on my stock LS7 heads ($1,800 and then done, LS7 will be built proof):
http://www.americanheritageperforman.../services.html
Last edited by jb78L-82; Apr 3, 2017 at 10:45 AM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
The Z06 LS7 issue is a valve guide/hollow sodium 2 piece exhaust valve issue...it has nothing to do with the piston type which is:
"Special cast pistons were developed for the LS7, which feature an anti-friction skirt coating, anodized ring lands, improving hardness and wear resistance. Larger-bore pistons are by nature heavier than their smaller-bore counterparts, and here the LS7 design team countered this tendency by moving the pin bosses inward and employing a shorter high-strength full-floating piston pin. This approach yields a piston assembly that is lighter, while the shorter pin represents a mechanically stiffer arrangement. With a flat-top design, the pistons deliver a compression ratio of 11:1. The mechanical line-up downstairs makes it abundantly clear that this mill was designed from the ground up to turn a number."
I plan on fixing my 2010 C6Z06 (3,800 miles and no problems yet but not waiting...) heads myself this summer from these guys with Moldstar 90 guides installed on my stock LS7 heads ($1,800 and then done, LS7 will be built proof):
http://www.americanheritageperforman.../services.html
"Special cast pistons were developed for the LS7, which feature an anti-friction skirt coating, anodized ring lands, improving hardness and wear resistance. Larger-bore pistons are by nature heavier than their smaller-bore counterparts, and here the LS7 design team countered this tendency by moving the pin bosses inward and employing a shorter high-strength full-floating piston pin. This approach yields a piston assembly that is lighter, while the shorter pin represents a mechanically stiffer arrangement. With a flat-top design, the pistons deliver a compression ratio of 11:1. The mechanical line-up downstairs makes it abundantly clear that this mill was designed from the ground up to turn a number."
I plan on fixing my 2010 C6Z06 (3,800 miles and no problems yet but not waiting...) heads myself this summer from these guys with Moldstar 90 guides installed on my stock LS7 heads ($1,800 and then done, LS7 will be built proof):
http://www.americanheritageperforman.../services.html
I was bringing to light that the LS6 had hyper pistons in it from the factory.....and that they work just fine. Not sure where you were going with it.....
Jebby
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
The reason most people have problems with hyper pistons is they require a wider piston ring gap and people don't check for that or think they can get away with tighter. They end up lifting ring lands.
Mike
Mike
This is exactly right and they also require a much tighter piston to wall....
Jebby
Jebby
Top ring gap is .030-.032" file fit and piston fit is snug.
Over 400 HP and torque for the last 10,000 miles, good so far.
I do remember most did not recommend hypers and more specifically Kieth Blacks at the time I was doing my build. However, I've had no issue with them, first 9.9:1 CR and now 10.6:1 CR.
Racer
Joined: Jun 2015
Posts: 315
Likes: 20
From: Vasteras, Sweden
I have Mahle forged with 28cc dome in my 468, with decked block and shaved heads i ended up with 10,5 CR. A bit on the high side, need 93oct, but works fine.
Rattles a bit when cold, but gets dead quiet warm.
Rattles a bit when cold, but gets dead quiet warm.
Last edited by clwi; Apr 3, 2017 at 01:05 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
There are hypereutectics...and then there are hypereutectics. The quality of what was designed into the OEM hi-perf engines these days is a LONG way from what is sold cheaply in the aftermarket. In addition, you have full engine management to control things at even the first hint of detonation.
For anything I'm going to lean on and expect to run hard...I'll put forged in it. There are tons of reasonably priced alternatives out there. Icon makes good ones, Mahle does too.
For a stock rebuild...the commonly available aftermarket hyper's might be an improvement...but I would still pay close attention to things.
JIM
For anything I'm going to lean on and expect to run hard...I'll put forged in it. There are tons of reasonably priced alternatives out there. Icon makes good ones, Mahle does too.
For a stock rebuild...the commonly available aftermarket hyper's might be an improvement...but I would still pay close attention to things.
JIM
Thread Starter
Team Owner
Joined: Jan 2006
Posts: 39,390
Likes: 171
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Just got back from the machine shop. They went ahead and tore it down and found some scoring and bearing wear. The rear main was down to some of the brass and the crankshaft is definitely scored up some, cam bearings, too. So the plan now is to replace all the bearings and freeze plugs, polish the crank, hone the cylinders, deck the block, it was out of spec, clean up the pistons and connecting rods, and put some new rings on the pistons. They think everything will be able to be reused after some clean up and recondition.
The machinist said all the wear was from dry starts after sitting for long periods. I have not been good about starting the car and letting it run every so often. Learned my lesson....
Gotta drive these cars otherwise.....
Good news is no major damage. Still more expensive than what I had planned on. But everything else has been that way, too.
The machinist said all the wear was from dry starts after sitting for long periods. I have not been good about starting the car and letting it run every so often. Learned my lesson....
Gotta drive these cars otherwise.....
Good news is no major damage. Still more expensive than what I had planned on. But everything else has been that way, too.
Thread Starter
Team Owner
Joined: Jan 2006
Posts: 39,390
Likes: 171
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
happens all the time, ... even when you tell them not to do it.
put it in writing on his estimate, have him sign with a penalty of xx ? $2000 ?
if they fail to follow instructions.
put it in writing on his estimate, have him sign with a penalty of xx ? $2000 ?
if they fail to follow instructions.
Thread Starter
Team Owner
Joined: Jan 2006
Posts: 39,390
Likes: 171
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Drifting
Joined: Oct 2012
Posts: 1,524
Likes: 61
From: Medina Ohio
There are hypereutectics...and then there are hypereutectics. The quality of what was designed into the OEM hi-perf engines these days is a LONG way from what is sold cheaply in the aftermarket. In addition, you have full engine management to control things at even the first hint of detonation.
For anything I'm going to lean on and expect to run hard...I'll put forged in it. There are tons of reasonably priced alternatives out there. Icon makes good ones, Mahle does too.
For a stock rebuild...the commonly available aftermarket hyper's might be an improvement...but I would still pay close attention to things.
JIM
For anything I'm going to lean on and expect to run hard...I'll put forged in it. There are tons of reasonably priced alternatives out there. Icon makes good ones, Mahle does too.
For a stock rebuild...the commonly available aftermarket hyper's might be an improvement...but I would still pay close attention to things.
JIM