Pistons or heads. Head spacers I haven’t seen on an LS and I would never run them personally. Thicker HGs work as well.


What compression ratio are you wanting to see? I’d be moving towards domed pistons with a longer rod but that is just me.

 

I’m moving to a set of ported ls3 heads and better quality valve train. I usually go 8.5:1, but it seems like a lot of forums talking about 9.0 to be an agreeable amount. I’d love to keep piston coverage. I am going to run a 10 in the truck or blow it up trying.

 

I am curious why you would like to lower the compression? with a solid tune you should be able to run all the way up to 11.0

 

Dished pistons. I meant to say dished not domed lol

 

I’ve never considered not lowering it. I want to be able to run on 91 and e~60, and since it’s a 406, it already moves out when it’s N/A. I think adding power with more boost is an attractive idea, and not having to worry about cylinder pressure. Not sure if taking it out .020 on a be. 3 block is really that big of a deal, but maybe it’s safer? Not sure. Willing to learn some stuff on this platform for sure. Already finding tons of differences in theories between my common head 6 cylinder stuff and these v8’s.

 

I was picking up what you were putting down 👍

 

You can clearly see the motor went south because of the ring gap. It pinched the top ring land and broke the top of the piston. You confirmed this fact when you stated the top ring was only .017

The top ring gap should have been significantly larger for up to 15 Lbs of boost. If you follow the chart below, 4in. X 0.006 =.024 for the top ring.




Now, with out seeing the rest or knowing exactly which parts were used, It's hard to say what other issues you may have had.

We would need to know what the bearing clearance were.
What piston and rod combo were used?
Was the Piston in the hole? If so how much?
What is the head gasket thickness? Looks like a Felpro?

 

Thanks for your comment. This is the type of stuff I need. When I first posted I didn’t have the pistons and rods pulled. I didn’t do this build, and would nevvvvvvverrrr have put any less than .024 for the top ring. For the replacement build, I’m considering .030 because I want to run 20-25 psi (or whatever it takes for 10.99) and considering a 25 shot to spool up for roll racing so I don’t have to kill the already inadequate 13” rotors with brake boosting. I believe most gaskets were Felpro.
head gasket measured between 1.45 and 1.71 in a few different spots. I believe the combo was Scat rods, eagle crank, and Summit .020 pistons. The guy I bought it from was mostly the money behind the project, and knows some stuff but nothing too technical. It actually had a 255lph Walbro pump in it 🤦‍♂️. Can you explain what you mean by in the hole? I’m not familiar. I can whip the plasti-gauge out tomorrow, but looks like the bearings are 1.7mm thick. The block wasn’t honed for the ARP main bolts, so I doubt any of the rods were checked. I think the guy just ordered parts, slapped it together and hoped for the best. Considering a dry sump, and don’t mind if it’s more maintenance. This isn’t a daily but I’d love to go out and stomp on the go fast pedal without worrying.
Are the preferred measurements metric or imperial for these? I default to metric but will change if it’s easier.

 

Typically we use standard when referring to stuff even though it is supposed to be a metric engine.
As to to the pistons. On an LS engine the pistons usually come out of the hole .003-.008 or so from the factory. Also referenced as above the deck.

 

And to add on to my novel up there, it seems like the bolts were torqued slightly different. Some broke loose with a gun, others had to be loosened with the jack handle with my feet almost coming off the ground. Head gaskets look inconsistent too.

I’m by no means a professional builder, but I do take my time and this build looks like it was done in a weekend with a case of Modelo.