Change pistons?
02-09-2011, 02:45 AM
#1
Racer
Thread Starter
Change pistons?
On a new Z06 if I get an A&A kit supercharger kit and blower cam with maybe a few other minor mods. Gotta pass Calif smog. Is it worth changing the pistons to lower compression and get forged pistons for strength? How much extra would it cost to have forged pistons put in? If the car would do 123 mph stock (1/4 mile), would it be able to do 135 with the A&A blower kit?
Last edited by qboy; 02-09-2011 at 02:48 AM.
02-09-2011, 04:00 AM
#2
On a new Z06 if I get an A&A kit supercharger kit and blower cam with maybe a few other minor mods. Gotta pass Calif smog. Is it worth changing the pistons to lower compression and get forged pistons for strength? How much extra would it cost to have forged pistons put in? If the car would do 123 mph stock (1/4 mile), would it be able to do 135 with the A&A blower kit?
Just a few LS7's blown up:
http://forums.corvetteforum.com/c6-z...-ls7-help.html
http://forums.corvetteforum.com/c6-z...failure-4.html
http://forums.corvetteforum.com/c6-f...-my-motor.html
By the way, I know a thing or two about blown up engines myself. My LS2 kicked the bucket after ~8k supercharged miles. The last link above, his lasted 10k in a LS7. Others have had theirs last a lot longer.
Last edited by BornSUPERCHARGED; 02-09-2011 at 04:07 AM.
02-09-2011, 04:54 AM
#3
Le Mans Master
You will probably do around 140mph+ with an A&A and the ls7 and bolts ons and cam, depending on your power level. My ls3 does 135-136mph(non z51 geared car) without exhaust or cam(+meth). I hope to see around 140mph with exhaust and a small cam.
02-09-2011, 11:31 AM
#4
Le Mans Master
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I dont think it's the pistons you have to worry about in the LS7. It's the thin cylinder walls.
By the way, I know a thing or two about blown up engines myself. My LS2 kicked the bucket after ~8k supercharged miles. The last link above, his lasted 10k in a LS7. Others have had theirs last a lot longer.
By the way, I know a thing or two about blown up engines myself. My LS2 kicked the bucket after ~8k supercharged miles. The last link above, his lasted 10k in a LS7. Others have had theirs last a lot longer.
This is true for almost all LS motors and also most other factory engines. My N/A subaru engine broke a ringland when boosted, my STI motor melted a piston when I turned up the boost, my LS2 snapped a ringland after 30K miles with a blower, etc etc etc...
You CAN certainly fail the factory cylinder liners on an LS7, but the piston will go first. My LS2 cracked the cylinder but that was because the piston broke inside it.
02-09-2011, 12:00 PM
#5
That is not true. The number 1 failure mode on the LS7 are the factory cast pistons. EdTaylor is making over 1000RWHP on stock cylinders with forged internals, and there are quite a few high HP stock block / forged piston builds; at least as many as there are blown up stock LS7s that had a ringland break off.
This is true for almost all LS motors and also most other factory engines. My N/A subaru engine broke a ringland when boosted, my STI motor melted a piston when I turned up the boost, my LS2 snapped a ringland after 30K miles with a blower, etc etc etc...
You CAN certainly fail the factory cylinder liners on an LS7, but the piston will go first. My LS2 cracked the cylinder but that was because the piston broke inside it.
This is true for almost all LS motors and also most other factory engines. My N/A subaru engine broke a ringland when boosted, my STI motor melted a piston when I turned up the boost, my LS2 snapped a ringland after 30K miles with a blower, etc etc etc...
You CAN certainly fail the factory cylinder liners on an LS7, but the piston will go first. My LS2 cracked the cylinder but that was because the piston broke inside it.
But, so that I can be more knowledgeable, do you have a link to the source for where you are getting the stats of LS7 failures? I'd like to see how many failures are because of dropped valves vs. cylinder walls cracking vs. melted pistons. You said pistons were the #1 reason, right? What's the percentage?
From the 2nd link I posted:
FYI, my 2nd motor was built with durability (most moving parts are forged) in mind but still lost it due to the snapped exhaust valve (forge stainless steel exhaust valve).
02-09-2011, 03:46 PM
#6
Team Owner
I guess in the end it really doesn't matter, eventually your engine will die. There are a lot of ways it can go out, and if you beat on it it'll just make it happen sooner.
But, so that I can be more knowledgeable, do you have a link to the source for where you are getting the stats of LS7 failures? I'd like to see how many failures are because of dropped valves vs. cylinder walls cracking vs. melted pistons. You said pistons were the #1 reason, right? What's the percentage?
From the 2nd link I posted:
But, so that I can be more knowledgeable, do you have a link to the source for where you are getting the stats of LS7 failures? I'd like to see how many failures are because of dropped valves vs. cylinder walls cracking vs. melted pistons. You said pistons were the #1 reason, right? What's the percentage?
From the 2nd link I posted:
I think that I will continue to have low cost fun with My 100 stock stock internaled Ls-7 with attached A&A kit.
I don't mind running a engine hard. But I'm careful about overreving
and what I'm doing. Some of the driving that I have seen here.
Would have taken out a most any engine overtime regardless of "Who
does the build"
The number one cause of engine failure is abuse on this forum.
If you drive with common sense with a good tune. You'll be OK!
02-09-2011, 10:27 PM
#8
02-09-2011, 10:44 PM
#9
Melting Slicks
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02-09-2011, 11:11 PM
#11
Melting Slicks
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No, it just gets really old when people post sh-t like "ls7 sleeves crack" with no other reason: "they are just too thin"...
I have read just about every ls7 failure on this site from Discussion to FI and the majority of failures are due to cast pistons/ring lands or the 2 pc exhaust valves falling apart. It sure hasn't been because of cylinder pressures have been out of the ranges of the "so called thin sleeves".
I guess no one posts those kinds of failures OR I have not read any lately.
I have read just about every ls7 failure on this site from Discussion to FI and the majority of failures are due to cast pistons/ring lands or the 2 pc exhaust valves falling apart. It sure hasn't been because of cylinder pressures have been out of the ranges of the "so called thin sleeves".
I guess no one posts those kinds of failures OR I have not read any lately.
02-10-2011, 09:20 AM
#12
Drifting
I haven't had the trouble's. But I don't have the same driving habit's.
I think that I will continue to have low cost fun with My 100 stock stock internaled Ls-7 with attached A&A kit.
I don't mind running a engine hard. But I'm careful about overreving
and what I'm doing. Some of the driving that I have seen here.
Would have taken out a most any engine overtime regardless of "Who
does the build"
The number one cause of engine failure is abuse on this forum.
If you drive with common sense with a good tune. You'll be OK!
I think that I will continue to have low cost fun with My 100 stock stock internaled Ls-7 with attached A&A kit.
I don't mind running a engine hard. But I'm careful about overreving
and what I'm doing. Some of the driving that I have seen here.
Would have taken out a most any engine overtime regardless of "Who
does the build"
The number one cause of engine failure is abuse on this forum.
If you drive with common sense with a good tune. You'll be OK!
Could not said it better than this, I had a LS3 making 712rwhp with a stock internals, a cam and a D1SC procharger, drove it for quite a while having fun until I gave a guy a drive, I thought he was a driver but he blew my motor within a 1/2 mile drive, after hearing his history, he had broke 3 forged Z06 motors, one built by Ligenfelter, one by Cartek and the other by VDP, I now realized the strenght of a motor is the driver and his habits.
