blu00rdstr

I blew my forged LS6 motor. Besides price, is there any advantage to running an iron block?

GTO_Scott

iTrader: (3)

A bit stronger platform for high output engines (Nitrous, turbo, supercharger, etc).

I'm split between an iron 408 or a LS2 402 setup myself.

Ferocity02

iTrader: (60)

Heres what I know about iron blocks, LQ9 specific... Pros: Price, avaliability, can be easily bored over, has 4.00" bore already for a 402ci, very strong for FI or N2O, most LS1 block parts should bolt right up. Cons: Weight

blu00rdstr

Are the cylinders any stronger? I think I cracked a cylinder at 17psi. It's hard to tell if the lines are cracks or not.

Cylinder number 3

MAC4264

You need an Iron block. In your case I would not bore it. What reason did you pull the head and look for a crack in the first place. If you think that you did something to cause that crack and seen something as a result (smoke, fluid loss, power loss)from it, then it is a crack. The only way to tell is to pressure test, or to have done a leak down before you pulled the head. I have seen engines sit short lenghts of time in humid environments and leave patterns that look like cracks but was actually just rust in the cylinder.

blu00rdstr

Well, I fixed a BOV flange leak, and after running 14psi I hit 17psi (it was tuned for 14psi). After that it started missing (bad). Then I noticed blowby at idle (worse) [Edit: It was puffing out the oil fill breater at idle], did a compression test with cylinder 5 at 30psi, and 4 and 7 at 90psi (really bad).

That's what made me pull a head and saw the lines in cylinder 3 (pic above). I couldn't put my head where the brake booster was, but the camera saw my Diamond forged pistons were hurt:

Cylinder number 5


Cylinder number 7

MAC4264

I understand. I have used Wisecos before and like there product. They do recommend nitrous on them and they do have a very thick top land. I have never used them in a forced induction application. Friends LT1 looks the same as yours and he is running JE, he has a serious tuning issue and needs to be running a FAST (18 psi). It has happened to him twice and ruined two blocks.

DONAIMIAN

iTrader: (18)

I think its more of a tuning issue. LS1's dont break because of too much power.

SUX2BU

iTrader: (14)

Yup. if you d that to a piston theres a pretty good chance you'll crack a cylinderwall. I went from aluminum to iron to aluminum. Would never do iron block ever again. the extra weight is just not worth it.

Wet 1

iTrader: (4)

That was certainly a tuning issue, not an alloy block failure. Stay with the aluminum block unless you want to run over 18 psi.

SporkLover

iTrader: (2)

Excuse my ignorance.... but you said you noticed blowby at idle? What do you mean by this?

ArcticZ28

iTrader: (14)

Oil getting past the rings, blowing smoke.

SporkLover

iTrader: (2)

Thats what I thought... thanks

Cstraub

iTrader: (1)

Horsepower. An iron block will make more power then an aluminum block. The iron block is more stable under power loads, less movement, you get better ring seal due to the stability, and less harmonics.

Chris