Ill have to keep my eye out for some. Just looking now and all I see is individuals.

 

Well I just spent the last three nights reading this thread. My eyes are burning and I want more. Now to start on the sunbird. Keep it up. Your madness has rubbed off. I am gonna stop the frame off on my Camaro to focus on my 86 SWB Chevy. Its sitting in my dads garage waiting for love. I will replicate your first set up and then just beat the shit out of it. Most of the odd parts I have. Just need a 5.3 and a GT45. neither will cost much.

 

I just got word my gen4 guts arrived

 

All the damage in this example could only happen from force applied downward - ring lands broken downward, rod beams buckled & twisted, those are compressive failures. Tensile failures (or sticking a ring) will break things in the opposite direction, from the bottom up. Rods would still be straight up until the point of total failure. Even good rod bolts are weaker than the beam section of a stock rod, so tension failures will start at the bolts or at the pin end. Rods rarely fail in tension in the beam section unless something else lets go first (as long as we aren't taking about stupid shit like Buick cast iron rods).

I don't doubt that the top rings butted, but the sure sign that butted rings isn't what broke the ring lands is that the tops are still on the pistons. The 2nd rings didn't butt - 2nd rings just don't do that, they don't run hot enough, and any heat that gets to the 2nd rings has to go through the top ring first. So the multiple ring land failures show you it was a progressive collapse-type failure, so it could have only come from above, and the only thing 'above' is something happening in the combustion chamber. Rings don't stick at or after BDC (on the upstroke), they're too cool by the time the piston gets down there. They stick at or after TDC when they are hottest or not at all.

It could have been from eating water during the head gasket failure (but not likely, in my opinion - usually the first one that eats water bends bad enough that none of the others get a chance to chow down on it), but it wouldn't have necessarily been confined to the hole where the gasket failed. It's amazing how stuff can jump back out thru the intake valve and over into cylinders completely unrelated to the original point of failure. I've seen one little 1/4" nut dropped down the intake take out six pistons.

But the way all the rods show (relatively) minor bending and all the broken pistons show the same failure mode says to me this was from normal combustion... just a little too much of it.

 

If you keep reading the article, they found it was a 4.8 and not a 5.3 hence the rpm difference and power band.

 

I know when we bent rods in a 302 it was from a Meth overdose, everything else was perfect, no HG failure.

We tried 4 injectors into the Cast Elbow trick last year on a 5.0 N/A build, engine had really weird fuel distribution, sometimes cylinder # 5 would be hot sometimes not sometimes times #3 was firing, sometimes not, it could have been a Mega Squirt issue but we never got the engine to rev past 3500, it was making 175 rwhp and had enough cam to go to 6500 rpm so it should have been pretty healthy if it would have revved...

 

got my gen4 shit today, wich you can see is so fuckin beast like its awesome...


they look like aftermarket rods and pistons.


full floating wrist pin instead of a pressed, and the rod is a H beam style instead of a I beam hopefully much stronger, as i know people with gen4 shit making more power than me and not bending anything.


gapped all my rings to 28-30 so its ready for some abuse.
i plan to hit it with 30lbs if the ignition system will let me.


motors built, reused the ls1 head gaskets, and slammed it all in and bolted up the trans and connected a few things, and thats where i am quitting for the day, think i might do a compression check tomorrow as soon as i get the converter tight and put the starter in, to see what kinda compression its at now, since it has flat top 5.3 pistons in it now, gunna have more squish


#ad

#ad

#ad

#ad

#ad

#ad

#ad

#ad

#ad

#ad

 

Hi Matt
What is the difference in the weight of the two assemblies ?

Gary

 

absolutely no idea haha, sorry dude i slammed this thing together just tonight in a few hours, anticipating burnouts tomorrow night and installing the glide in the sunbird saturday! lol

 

Seeing your build has given me much improved confidence in my stock short block Magnum. Similar distance between the piston top and top ring, the magnum rods look similar to your original rods too. I gapped my rings to .028" as well.

 

nice, i would say 550whp is safe!

and 600 is starting to push it haha

 

All the damage in this example could only happen from force applied downward - ring lands broken downward, rod beams buckled & twisted, those are compressive failures. Tensile failures (or sticking a ring) will break things in the opposite direction, from the bottom up. Rods would still be straight up until the point of total failure. Even good rod bolts are weaker than the beam section of a stock rod, so tension failures will start at the bolts or at the pin end. Rods rarely fail in tension in the beam section unless something else lets go first (as long as we aren't taking about stupid shit like Buick cast iron rods).

I don't doubt that the top rings butted, but the sure sign that butted rings isn't what broke the ring lands is that the tops are still on the pistons. The 2nd rings didn't butt - 2nd rings just don't do that, they don't run hot enough, and any heat that gets to the 2nd rings has to go through the top ring first. So the multiple ring land failures show you it was a progressive collapse-type failure, so it could have only come from above, and the only thing 'above' is something happening in the combustion chamber. Rings don't stick at or after BDC (on the upstroke), they're too cool by the time the piston gets down there. They stick at or after TDC when they are hottest or not at all.

It could have been from eating water during the head gasket failure (but not likely, in my opinion - usually the first one that eats water bends bad enough that none of the others get a chance to chow down on it), but it wouldn't have necessarily been confined to the hole where the gasket failed. It's amazing how stuff can jump back out thru the intake valve and over into cylinders completely unrelated to the original point of failure. I've seen one little 1/4" nut dropped down the intake take out six pistons.

But the way all the rods show (relatively) minor bending and all the broken pistons show the same failure mode says to me this was from normal combustion... just a little too much of it.

I agree that the failure does not look like it was caused by the rings butting. If it was caused by downward compressive force alone, wouldn't there have to be some sort of detonation present? Others seem to make more than 700whp without twisting rods and breaking ring lands. Assuming we believe the magazine hype they logged over 70 pulls on the 5.3 at over 1000hp (including a few at 1300hp). Seems like if rods/pistons were the weak point it would have shown up there. I know theres a big diff between eng and chassis dynos, 690hp and 1300 is also quite a jump. Then there are others in heavy trucks making 700-800 without issue. I just have a hard time believing power alone caused the problem. Could be... sure wish I had some LS2 pistons and rods now!

There are 2 articles. One is a 5.3 the other a 4.8. My statement was correct.

 

There's no evidence of detonation anywhere - no pecker marks on the piston tops, no hammered upper rod bearings, no speckled spark plugs. And detonation won't do the kind of damage shown, the pressure spike/shock loads are too sharp & short. Plus, these pistons have the top ring so close to the top, it's nearly impossible that there could have been detonation and not pulled at least some of the piston tops off.

The water ingestion scenario is more plausible than detonation, and too much power is more plausible than water ingestion. I've seen a gulp of water bend rod beams before (and even then they're usually only bent in one direction, and don't look like these with bends going every which way and also twisted), but I've never seen it break lower ring lands. The one explanation that ticks all the boxes in respect to the damage shown is too much power.

I've done identical piston damage to a ZZ3 crate motor at around 550whp, though not the rod bending part - ZZ3's PM rods are stronger, and the pistons weaker, than the stock 5.3 pieces.

 

running great as of 4pm today

 

Do you have any pics of 4.8L pistons? I know the compressions height is the same or withing a thousandth or two, but I'm curious if being flat tops of they are any different from the 5.3L HO flat tops like you have.

 

I'm pretty happy about that as well ;-)

 

Nice work!

 

Probably needs a mandatory driveway burnout to get the rings seated in the new bores.

 

Those are not H beam. They are I beams.

They do look stronger though.

Regards,
TonyR