6.0L with LS6 heads, spark issues,

[busta9876]

I usually do stock engine tunes for engine swaps, etc, but a local kid wanted me to try to make his 02 avalanche run a little better. He said it was a 6.0L with higher compression, he doesnt know much about it really. It has the 243 heads, which i read are the LS6. The computer was a stock 99 truck tune, with the displacement changed, that was about it. VIN didn't match, AC doesnt work, etc. I'm starting over with a fresh flash of his VIN to get rid of some communication codes set and the non - functioning a/c. Not sure who did his initial tune, not sure I want to.

Anyone have any idea what compression he's running? I already told him run highest pump octain he can find, and needs a 160 stat.

So I'm trying to get this figured out for him. Spark knock is up to 8 degrees in some places in the histogram. Should I just go and remove timing in those areas, or should I change the whole table.

I'm so used to MAP vs RPM this grm/cyl is confusing to me right now on the timing tables.

attached is a log.

[WS6FirebirdTA00]

No idea on compression unless you post some specs on the heads. Are they milled? Is it a stock 6L bottom end?

Post the tune. LS6 heads need little timing in the tune.

[69lt1bird]

243 heads have a 64cc combustion chamber stock. If they are stock and stock headgaskets, that should be around 10.8:1 CR

Used for calculation:
4.00 bore
3.622 stroke
.052 headgasket
flat top pistons
pistons .005 above the deck

[busta9876]

Engine is stock bottom end LQ4, with stock 243 heads.

[454SuperSport]

the 99-00 truck OS sucks, flash a stock 02 avalanche file back in it and start from there. ask the guy if they just loaded a tune into his stock pcm or actually put a 99 pcm in it. btw, the lq4 has dish pistons and should be between 10.0-10.5 with the 243's.

[Gh0st]

243's run just fine on 22-24 degrees of timing.

[Pharcyde50]

The truck tunes I have seen have way less than 22-24 degrees timing. I would probably try around 10 degrees max and go from there. With 22-24 it will probably ping if he tows anything. I've found my 6.0l setup with 243's likes around 20 degrees max and my trans am is way lighter than a truck.

[Gh0st]

The truck tunes I have seen have way less than 22-24 degrees timing. I would probably try around 10 degrees max and go from there. With 22-24 it will probably ping if he tows anything. I've found my 6.0l setup with 243's likes around 20 degrees max and my trans am is way lighter than a truck.

You're most likely right. I did not take in to account this was a truck!