maybe the piston is expanding as it heats up thus reducing the noise ?

 

yep, that's what it does. but at the same time lifters pump up after the first start also. hints why i thought it was the lifters.

 

Yep, that's 100% correct, classic sign of piston slap. Many of the GENIII's are known for this, but it usually doesn't progress past the first few minutes of opertation. It's caused by the short skirt pistons rocking in the cylinders until they expand from heat. I know that the 03+ LQ9's received teflon coated piston skirts to help combat this, I believe that it helped. Not sure about the other GENIII's though

As I mentioned, my old ZZx SBC sounded like a diesel when I first started it up (I de-sensitized the knock sensor with some teflon lol), then as it warmed up it would quiet down to a noticable tap. The piston design in that engine had a centered wrist pin that caused the same piston rocking as the GENIII's short skirt pistons. My step-father and I chased after that noise for a long time until we finally contacted my father (race engine builder) who told us that's the way it is. That engine was in my mother's 82 Camaro for I don't know how many miles, then I put over 80K of hard driving miles on it in my 85 MonteSS, when I trade the car in on my current truck back in 99. The engine was performing flawlessly at the time....now the trans is another story (I limped the failing 200R4 into the parking lot when I traded the car in, thank God that the ride there was down hill lol)

 

BTW, that engine did not have excessive oil consumption (about 1/2 qt every 1k, which is within factory acceptable spec), and I was running Texaco Havoline dino oil at the time...I can't remember what weight though, I think it was 10w-40 in the summer.

 

i'm thinking a little thicker oil just to make sure the thing doesn't beat itself to death. but i don't want to go to thick and hurt my turbo.

 

That is probably exactally what you did.

 

oh well, when ig et some money together i'll get some pistons and put it back together. i'm thinking just wiseco ls1 pistons with stock rods. with -11 cc pistons it will give me 8.7 or 8.8 IIRC with stock rods then later if i swap out rods for better ones it will give me 9.2:1.

 

I wouldn't put that together with stock rods unless they are the LQ9/LS2 style. The scat I beam is another alternitive. Those eairly rods are weak and will bend on you if you push them.

 

well if that's the case i'll have to just keep saving money and hope it don't blow up lol. this thing is nasty by the way. i got on it for just a second last night. lets just say the wife almost puked. she reached forward like she was going to push the front of the tahoe down. i thought the old turbo came in hard. with the new torque converter and all, this turbo come in fast. i have to get the other fuel pump wired in. its installed but i think the wire i put on there is too small so i'm going to change it out before i run it.

 

i'm pretty sure its the pistons. it is smoking just a tad little bit as it idles. its not much and hard to see but its there. not alot of blow by really. if you watch the tube on the passenger side(fresh air tube) you can see a tad bit of smoke puff out every once in awhile. it doesn't do it when you first start it so that tells me the valve seals are good. they better be any way just got the heads done.