I was under the assumption that we definitely "knew" there was a ring problem.. sure sounds like one to me but you need to do a leakdown to be completely sure..

As for crankcase ventilation, I am running a catchcan from the pcv valve that was from thunderracing for "ls" engines.. and a deutsche filter from autozone on the fresh air line.. I didn't want to let un-metered air into the engine with regular breathers.. my old setup was letting oil into the intake and this was my fix with the new rebuild.. It was not 3-400$ though, quite a bit cheaper.

Like Injuneer though I seriously doubt has anything to do with the ring problem.

I would offer a suggestion that perhaps the engine was a bit worn and the extra compression/power on a worn ring may of done the damage.. OR when the heads were swapped some debris got in there and damaged the rings causing one to fail.. As was mentioned above though do a leakdown to be sure..

 

hey guys I talked to my guy who built the engine for me who has my car at his shop wtg on a fix, and told him about all your help you've given me....he hasn't done a leak test yet but he said he did pull the pan and he's got a camara that he puts up in them to see if it has scared the piston walls and he said he saw one cylinder that was a lil scarred but found my problem. He told me the same thing, about the new build adding extra compression on the worn engine which caused the ring to blow.

Have you guys heard of this: he said that in 96 GM updated the pistons to improve them somehow but they actually made them weaker or something b/c all the 96's he's ever had a problem with as far as rings or pistons has had the updated pistons/and or rings in them from the factory.

Anyways he said I could either sleave the one cylinder or punch .30 over put all new forged in it w/mahle rings and it should be good to go. Now as for the blowback I liked the idea of the cheap way you did it instead of a high dollar deal from aftermarket. As long as it keeps the oil away from the TB.

My concern is after I replace pistons and rings and update what next have I forgotten to upgrade that will cost me another tear dwn. to update you know, kinda wished I'd left it alone, I keep getting deeper and deeper!

 

well i've got my car tore down guys and i've never heard of this but the guy that's building my engine said he's saw a few that has done this......what was the culprit all along was a piston. The piston actally had a big chunk gone off from it which was causing all my problems. He stated that in 96 GM changed pistion designs or something halfway through the year supposdly making them better but when modded they were weaker or something whatever all i know is I need some good pistons and rings and want your opinion on what to do from here.


Plans: Fix the car right street/strip car still running AC if that tells you anything. Strip time maybe 3-4 times per year. His plans is to put speed pro pistions, mahle rings, and punch .30 over. What all should i really do?

What pistons, rings etc are good for the budgeter in mind but strong also.
-should i turn the crank?
-any new rod bolts,caps, etc.?
-b/c internals i'm not real confident on about what's the right and wrong thing to do my budget is around 2500 all around and labor is 800 is that in the neighborhood?

thanks and sorry just want all your opinions, it means alot for me

I want to be easy on the car but if ever want to give it hell i want it to hold over 3000 miles on this build ya know

 

The stock LT1 pistons are hypereutectic, made by Mahle in Brazil. I'm not aware of any changes made over the years. They are fairly durable.... unless you are running a power adder and encounter detonation. In that event, it isn't unusual for a chunk to break off the top ring land, since hypereutectic pistons are very brittle.

 

dang with that said (thanks) what do i need to do......is the speed pro aftermarket pistons the same kind (hypereutectic) and also what would have caused that detonation besides pump gas.....i guess the biggest detonation causing problem you guys see?

 

Detonation is caused by low octane, hot spots on heads or pistons, too hot plugs, lean mixture, excessive coolant temperature, excessive inlet air temperature, or any combination of those.

The hypereutectic pistons are generally fine on an NA engine. You'll have to check the specific piston you are looking at to see what its made out of. You normally only see problems when you use nitrous or forced induction. But the cost of a set of new forged pistons is not a whole lot more than the hypers.

 

Broken piston like that is most likely detonation caused.

Did you ruin the LT4 intake to make it fit the LT1 heads or mill the heads to fit?? If not a vacuum leak could have caused a lean cylinder and detonation.

For 96 the TRUCK engines changed to the gen 1 Votec which may have had a piston change as well. I am with Injuneer though on never having heard anything about an LT1 piston change, the rods were changed in like 94 there were about 4-5 intake castings, 2 iron head castings, about 4 aluminum head casting, LT4 heads and intake, but far as I knew the pistons, block and LT1 cranks were all the same, there was an LT4 rods and crank as well.

The LT4 intake has more material above the port which will stop it from bolting down too LT1 heads properly, internally though it is JUST AN LT1 INTAKE.